This article records new

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

archosaur Archosauria () or archosaurs () is a clade of diapsid sauropsid tetrapods, with birds and crocodilians being the only extant taxon, extant representatives. Although broadly classified as reptiles, which traditionally exclude birds, the cladistics ...

s of every kind that was described during the year 2021, as well as other significant discoveries and events related to

paleontology Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure ge ...

of archosaurs that occurred in 2021.

Pseudosuchians

New pseudosuchian taxa

General pseudosuchian research

* A study on the phylogenetic relationships of pseudosuchian archosaurs, aiming to determine drivers of body size evolution in this group, is published by Stockdale & Benton (2021); the study is subsequently criticized by Benson ''et al.'' (2022). * The first occurrence of the track type ''" Chirotherium" lulli'' (inferred to be produced by a pseudosuchian archosaur) from western North America is reported from the Owl Rock Member of the Chinle Formation (

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

) by Milner ''et al.'' (2021). * A study on the skeletal anatomy and phylogenetic relationships of '' Revueltosaurus callenderi'' is published by Parker ''et al.'' (2021). * A study on the skull anatomy and likely feeding habits of '' Effigia okeeffeae'' is published by Bestwick ''et al.'' (2021).

Aetosaur research

* Description of the braincase of '' Aetosauroides scagliai'', based on data from specimens from the Upper Triassic Candelária Sequence (

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

), is published by Paes Neto ''et al.'' (2021). * Description of the skull ''Aetosauroides scagliai'', and a study on the likely diet and paleobiology of this aetosaur, is published by Paes Neto ''et al.'' (2021). * A study on the anatomy of the axial skeleton of ''Aetosauroides'' is published by Paes-Neto ''et al.'' (2021), who propose that ''Polesinesuchus aurelioi'' is a

junior synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...

of ''Aetosauroides scagliai''. * An incomplete, largely articulated postcranial skeleton of a basal aetosaur, possibly distinct from ''Aetosauroides scagliai'', and preserving anatomical features which aren't often preserved in aetosaur specimens (including extensive appendicular armor and a well-preserved caudal ventral carapace), is described from the Upper Triassic Ischigualasto Formation (

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

) by Hecket, Martínez & Celeskey (2021). * An

osteoderm Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinct amph ...

of '' Typothorax coccinarum'' with punctures and scores which are likely bite marks is described from the Upper Triassic Chinle Formation (

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

, United States) by Drymala, Bader & Parker (2021), who interpret this finding as supporting the hypothesis that aetosaurs were prey items of large archosauromorphs. * Reyes, Parker & Marsh (2021) describe the first complete articulated skull of ''Typothorax coccinarum'' from the Owl Rock Member of the Chinle Formation (

Petrified Forest National Park Petrified Forest National Park is a national park of the United States in Navajo and Apache counties in northeastern Arizona. Named for its large deposits of petrified wood, the park covers about , encompassing semi-desert shrub steppe as wel ...

), and evaluate the implications of this specimen for the knowledge of the relationships and morphological diversity of aetosaurs. * A study on the biomechanical properties of the skull of '' Neoaetosauroides engaeus'' is published by Taborda, Desojo & Dvorkin (2021). * Revision of isolated braincases of ''

Desmatosuchus ''Desmatosuchus'' (, from Greek language, Greek δεσμός ''desmos'' 'link' + σοῦχος ''soûkhos'' 'crocodile') is an extinct genus of archosaur belonging to the Order Aetosauria. It lived during the Late Triassic. Description ''Desma ...

'' from the ''Placerias'' Quarry locality in the Chinle Formation (

) is published by von Baczko ''et al.'' (2021), who report the presence of two species of ''Desmatosuchus'' (''D. spurensis'' and ''D. smalli'') at the ''Placerias'' Quarry.

Crocodylomorph research

* A study on the morphological diversity of skull and jaw shape in crocodylomorphs throughout their evolutionary history is published by Stubbs ''et al.'' (2021). * A study on the evolution of the skull morphology in crocodyliforms is published by Felice, Pol & Goswami (2021). * A study on the anatomy, phylogenetic relationships and stratigraphy of the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen of '' Notochampsa istedana'' is published by Dollman ''et al.'' (2021). * A study on the skull anatomy and phylogenetic placement of '' Eopneumatosuchus colberti'' is published by Melstrom, Turner & Irmis (2021). * A study on the bite force in mesoeucrocodylians throughout their evolutionary history is published by Gignac, Smaers & O'Brien (2021). * A study on feeding habits of

notosuchia Notosuchia is a clade of primarily Gondwanan mesoeucrocodylian Crocodylomorpha, crocodylomorphs that lived during the Jurassic and Cretaceous. Some phylogeny, phylogenies recover Sebecosuchia as a clade within Notosuchia, others as a sister group ...

ns from the Upper Cretaceous Bauru Group (

), as indicated by stable carbon and oxygen isotope data from tissues of notosuchians from two sites from Bauru Group, is published by Klock ''et al.'' (2021). * Description of

coprolite A coprolite (also known as a coprolith) is fossilized feces. Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animal's behaviour (in this case, diet) rather than morphology. The name ...

s from the Upper Cretaceous

Adamantina Formation The Adamantina Formation is a geological Formation (geology), formation in the Bauru Basin of western São Paulo (state), São Paulo state in southeastern Brazil. Its strata date back to the Late Cretaceous epoch of the Cretaceous, Cretaceous Per ...

(

) found in association with skeletons of baurusuchid and sphagesaurid crocodylomorphs, and a study on the implications of these coprolites for the knowledge of the diet of these crocodylomorphs, is published by de Oliveira ''et al.'' (2021). * A study on the morphological variation in the dentition of uruguaysuchid crocodylomorphs is published by Figueiredo & Kellner (2021). * A study on the bone

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissue (biology), tissues. Histology is the microscopic counterpart to gross anatomy, which looks at large ...

and growth dynamics of ''

Araripesuchus ''Araripesuchus'' is a genus of extinct crocodyliform that existed during the Cretaceous period of the late Mesozoic era some 125 to 66 million years ago. ''Araripesuchus'' is generally considered to be a notosuchian (belonging to the clade Mes ...

'', based on data from specimens from the La Buitrera Palaeontological Area (

Río Negro Province Río Negro (, ''Black River'') is a province of Argentina, located in northern Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean. Its cap ...

), is published by Fernández Dumont ''et al.'' (2021). * A study on the resistance to stress of the skull of ''Araripesuchus gomesii'', and on its implications for the knowledge of likely diet of this crocodylomorph, is published by Nieto ''et al.'' (2021). * New partially preserved skull of '' Campinasuchus dinizi'' is described from the Fazenda São José (Adamantina/Vale do Rio do Peixe Formation,

) by Darlim ''et al.'' (2021), who evaluate the implications of this specimen for the knowledge of the distribution of

baurusuchids Baurusuchidae is a Gondwanan Family (biology), family of mesoeucrocodylians that lived during the Late Cretaceous. It is a group of terrestrial hypercarnivorous crocodilians from South America (Argentina and Brazil) and possibly Pakistan. Baurusu ...

in the Late Cretaceous of South America. * The first known baurusuchid yearling is described from the

(

) by dos Santos ''et al.'' (2021). * New baurusuchid specimen, providing new information on the skeletal growth in baurusuchids, is described from the Upper Cretaceous

(Brazil) by Marchetti ''et al.'' (2021). * A study on the anatomy of the endocranial structures of '' Zulmasuchus querejazus'', and on its implications for the knowledge of the head posture, hearing capabilities and likely lifestyle of this sebecid, is published by Pochat-Cottilloux ''et al.'' (2021). * New soft tissue records for thalattosuchians are reported from the Late Jurassic localities of Wattendorf and Painten (Bavaria,

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

) by Spindler ''et al.'' (2021), who interpret their findings as indicating the skin of metriorhynchids lacked any traces of scales or scutes and instead showed folded and transverse fibers. * A study on the nasal and paranasal anatomy of thalattosuchians, and on its implications for the knowledge of the evolution of the

paranasal sinus Paranasal sinuses are a group of four paired skeletal pneumaticity, air-filled spaces that surround the nasal cavity. The maxillary sinuses are located under the eyes; the frontal sinuses are above the eyes; the Ethmoid sinus, ethmoidal sinuses a ...

system and

nasopharyngeal The pharynx (: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates, though its ...

ducts in Thalattosuchia, is published by Cowgill ''et al.'' (2021). * Description of the cranial and endocranial anatomy of '' Macrospondylus bollensis'' is published by Wilberg ''et al.'' (2021). * A study on the innervation of the rostrum of metriorhynchoid thalattosuchians, and on its implications for the knowledge of the

somatosensory The somatosensory system, or somatic sensory system is a subset of the sensory nervous system. The main functions of the somatosensory system are the perception of external stimuli, the perception of internal stimuli, and the regulation of bod ...

abilities of these crocodylomorphs, is published by Bowman ''et al.'' (2021). * Isolated metriorhynchid tooth crowns, representing some of the most recent known occurrences of Metriorhynchidae worldwide, are described from the

Valanginian In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 137.05 ± 0.2 Ma and 132.6 ± 0.2 Ma (million years ago). The Valanginian Stage succeeds the Berriasian Stage of the Lower Cretac ...

Kopřivnice Formation (

Czech Republic The Czech Republic, also known as Czechia, and historically known as Bohemia, is a landlocked country in Central Europe. The country is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the south ...

) by Madzia ''et al.'' (2021), who interpret these specimens as evidence of the presence of two distinct lineages of geosaurin metriorhynchids in the area of Czech Republic during the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

. * A study on the anatomy of the braincase of a metriorhynchid specimen belonging or related to the species ''" Metriorhynchus" brachyrhynchus'', and on the evolution of neurosensory and endocranial systems of metriorhynchids, is published by Schwab ''et al.'' (2021). * A study on the anatomy of the snout of '' Dakosaurus andiniensis'', and on the evolution of the facial anatomy of thalattosuchians, is published by Fernández & Herrera (2021), who interpret their findings as indicative of presence of anatomical adaptations likely helping drainage of nasal glands (probably excreting salt). * A study on histology and stable isotope geochemistry of the fossil material of '' Goniopholis'' and '' Dyrosaurus'', and on their implications for the knowledge whether these crocodylomorphs were

ectotherm An ectotherm (), more commonly referred to as a "cold-blooded animal", is an animal in which internal physiological sources of heat, such as blood, are of relatively small or of quite negligible importance in controlling body temperature.Dav ...

s or

endotherm An endotherm (from Greek ἔνδον ''endon'' "within" and θέρμη ''thermē'' "heat") is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions inst ...

s, is published by Faure-Brac ''et al.'' (2021). * A study on the evolution of tethysuchian and gavialoid crocodylomorphs from the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

to the

Thanetian The Thanetian is, in the International Commission on Stratigraphy, ICS Geologic timescale, the latest age (geology), age or uppermost stage (stratigraphy), stratigraphic stage of the Paleocene epoch (geology), Epoch or series (stratigraphy), Serie ...

is published by Jouve (2021). * A study on the histology of the humeri and femora of '' Hyposaurus rogersii'' is published by Pellegrini ''et al.'' (2021). * A study on the anatomy of the braincase and inner ear of '' Rhabdognathus aslerensis'' is published by Erb & Turner (2021). * A study on the anatomy of the postcranial skeleton of '' Cerrejonisuchus improcerus'' is published by Scavezzoni & Fischer (2021), who also provide new information on the anatomy of the postcranial skeletons of '' Congosaurus bequaerti'' and '' Hyposaurus rogersii'', and provide evidence of a distinctive postcranial anatomy of dyrosaurids among crocodyliforms. * New fossil material of '' Deltasuchus motherali'', providing new information on changes in the skeleton of this

crocodyliform Crocodyliformes is a clade of Crurotarsi, crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the ...

during the

ontogeny Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the ovum, egg to adult. The term can also be used to refer to t ...

, and indicative of dietary shifts from juvenile to adult, is described from the

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

Woodbine Formation The Woodbine Group is a geological formation in east Texas whose strata date back to the Early to Middle Cenomanian age of the Late Cretaceous. It is the producing formation of the giant East Texas Oil Field (also known as the "Black Giant") fr ...

(

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

) by Drumheller ''et al.'' (2021), who also study the phylogenetic relationships of ''D. motherali'', and identify an endemic clade of Appalachian crocodyliforms, which they name Paluxysuchidae. * Redescription and a study on the phylogenetic relationships of ''

Duerosuchus ''Duerosuchus'' is an extinct genus of crocodilian. Remains have been found from Corrales del Vino in Zamora, Spain, and are middle Eocene in age (about 40 million years old). ''Duerosuchus'' is known from a single skull that is incomplete but ...

piscator'' is published by Narváez ''et al.'' (2021). * A study on the phylogenetic relationships and the evolutionary history of

crocodilia Crocodilia () is an order of semiaquatic, predatory reptiles that are known as crocodilians. They first appeared during the Late Cretaceous and are the closest living relatives of birds. Crocodilians are a type of crocodylomorph pseudosuchia ...

ns is published by Rio & Mannion (2021). * New fossil material of ''

Deinosuchus ''Deinosuchus'' is an extinct genus of eusuchian, either an Alligatoroidea, alligatoroid Crocodilia, crocodilian or a stem-group crocodilian, which lived during the Late Cretaceous around . The first remains were discovered in North Carolina ...

'', representing one of the earliest records of this genus in North American reported to date, is described from the

Menefee Formation (New Mexico, United States) by Mohler, McDonald & Wolfe (2021). * Description of the

fossil material from the Eocene (

Lutetian The Lutetian is, in the geologic timescale, a stage (stratigraphy), stage or age (geology), age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it ...

) Ikovo locality (

Ukraine Ukraine is a country in Eastern Europe. It is the List of European countries by area, second-largest country in Europe after Russia, which Russia–Ukraine border, borders it to the east and northeast. Ukraine also borders Belarus to the nor ...

), including the easternmost record of diplocynodontines in Europe reported to date, is published by Kuzmin & Zvonok (2021), who also review the fossil record and

biogeography Biogeography is the study of the species distribution, distribution of species and ecosystems in geography, geographic space and through evolutionary history of life, geological time. Organisms and biological community (ecology), communities o ...

of crocodyliforms from the Paleocene and Eocene of Europe. * Description of additional fossil material of ''

Tsoabichi ''Tsoabichi'' (from Shoshoni language, Shoshone "''tso’abichi’''", meaning "monster") is an extinct genus of caimanine crocodylian. Fossils are known from the Green River Formation in Wyoming, and date back to the Ypresian stage of the Eocene ...

greenriverensis'' from the Eocene

Green River Formation The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes in three basins along the present-day Green River (Colorado River), Green River in Colorado, Wyoming, and Utah. The sedimen ...

, providing further evidence for its

caiman A caiman ( (also spelled cayman) from Taíno language, Taíno ''kaiman'') is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within the Alligatoridae family (biology), family, the other being alligators. ...

ine affinities, and a study on the evolutionary history of caimanines is published by Walter ''et al.'' (2021). * Cidade & Rincón (2021) report the first occurrence of '' Acresuchus pachytemporalis'' from the Miocene Urumaco Formation (

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

), expanding known geographic distribution of this species. * Description and a study on the taxonomic status of the crocodylians from the

Neogene The Neogene ( ,) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period million years ago. It is the second period of th ...

Irrawaddy Formation (

Myanmar Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ...

), including one of the oldest records of the genus ''

Gavialis ''Gavialis'' is a genus of crocodylians that includes the living gharial ''Gavialis gangeticus'' and one known extinct species, '' Gavialis bengawanicus.'' ''G. gangeticus'' comes from the Indian Subcontinent, while ''G. bengawanicus'' is know ...

'' reported to date, is published by Iijima ''et al.'' (2021). * Revision of the taxonomy and a study on the phylogenetic relationships of the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

tomistomines from

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

and

Malta Malta, officially the Republic of Malta, is an island country in Southern Europe located in the Mediterranean Sea, between Sicily and North Africa. It consists of an archipelago south of Italy, east of Tunisia, and north of Libya. The two ...

is published by Nicholl ''et al.'' (2021). * A study on the phylogenetic relationships of '' Voay robustus'', based on mitochondrial genomic data, is published by Hekkala ''et al.'' (2021). * Description of a new skull of '' Crocodylus anthropophagus'' from the DK site at Olduvai (

Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...

), representing the oldest fossil of a member of this species reported to date, and a study on the phylogenetic relationships of this species is published by Azzarà ''et al.'' (2021)

Non-avian dinosaurs

New dinosaur taxa

General non-avian dinosaur research

* A study on the impact of the disparity between

neonate In common terminology, a baby is the very young offspring of adult human beings, while infant (from the Latin word ''infans'', meaning 'baby' or 'child') is a formal or specialised synonym. The terms may also be used to refer to Juvenile (orga ...

s and adults on the structure and diversity of dinosaur communities is published by Schroeder, Lyons & Smith (2021), who claim that communities with giant theropods lacked carnivores weighing 100 to 1000 kg, and argue that juveniles of giant theropod species likely filled the

mesocarnivore A mesocarnivore is an animal whose diet consists of 30–70% meat with the balance consisting of non-vertebrate foods which may include insects, fungi, fruits, other plant material and any food that is available to them. Mesocarnivores are from ...

niche, resulting in reduced overall taxonomic diversity; their conclusions are subsequently contested by Benson ''et al.'' (2022). * Evidence of cessation of longitudinal skeletal growth in non-avian dinosaurs, inferred from a study of the articular surfaces of long bones, is presented by Rothschild & Witzmann (2021). * A study aiming to determine the survivorship curves of ''

Albertosaurus ''Albertosaurus'' (; meaning "Alberta lizard") is a genus of large tyrannosaurid theropod dinosaur that lived in northwestern North America during the early to middle Maastrichtian age of the Late Cretaceous period, about 71 million yea ...

sarcophagus'', '' Gorgosaurus libratus'', '' Daspletosaurus torosus'', ''

Tyrannosaurus ''Tyrannosaurus'' () is a genus of large theropod dinosaur. The type species ''Tyrannosaurus rex'' ( meaning 'king' in Latin), often shortened to ''T. rex'' or colloquially t-rex, is one of the best represented theropods. It lived througho ...

rex'', '' Maiasaura peeblesorum'' and ''

Psittacosaurus ''Psittacosaurus'' ( ; "parrot lizard") is a genus of extinct ceratopsian dinosaur from the Early Cretaceous of what is now Asia, existing between 125 and 105 million years ago. It is notable for being the most species-rich non-avian dinosaur ...

lujiatuensis'' in populations with an age distribution which was stable in shape over time is published by Griebeler (2021). * A study aiming to determine whether the presence of

keratan sulfate Keratan sulfate (KS), also called keratosulfate, is any of several sulfated glycosaminoglycans (structural carbohydrates) that have been found especially in the cornea, cartilage, and bone. It is also synthesized in the central nervous system whe ...

is exclusive evidence for the presence of

medullary bone The medullary cavity (''medulla'', innermost part) is the central cavity of bone shafts where red bone marrow and/or yellow bone marrow (adipose tissue) is stored; hence, the medullary cavity is also known as the marrow cavity. Located in the ma ...

in dinosaur fossils (and therefore whether it can be used to identify dinosaur specimens as gravid females) is published by Canoville ''et al.'' (2021). * A study on the variation in tail anatomy and length across the Dinosauria is published by Hone, Persons & Le Comber (2021). * A study on the possibilities of determination of the presence of

sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

in dinosaurs, evaluating whether the previous method used for dinosaurs correctly recognizes living animals as dimorphic, is published by Motani (2021). * A study on the role of climate in shaping the geographic distribution of Mesozoic dinosaurs is published by Chiarenza ''et al.'' (2021). * Review of the fossil record of

Carnian The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227.3 ...

dinosaurs from South America is published by Novas ''et al.'' (2021), who also interpret ''

Chindesaurus ''Chindesaurus'' ( ) is an extinct genus of basal saurischian dinosaur from the Late Triassic (213-210 million years ago) of the southwestern United States. It is known from a single species, ''C. bryansmalli'', based on a partial skeleton recov ...

'', ''

Daemonosaurus ''Daemonosaurus'' is an extinct genus of possible theropod dinosaur from the Late Triassic of New Mexico. The only known fossil is a skull and neck fragments from deposits of the latest Triassic Chinle Formation at Ghost Ranch. ''Daemonosaurus'' ...

'' and '' Tawa'' as likely late-surviving members of Herrerasauria. * A study on dinosaur trackways that show changes in direction from

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

and

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

sites in North and South America, Europe and Asia is published by Lockley ''et al.'' (2021). * Fossil trackways made by

theropods Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

, ornithopods and possibly

ankylosaurs Ankylosauria is a group of herbivorous dinosaurs of the clade Ornithischia. It includes the great majority of dinosaurs with Armour (zoology), armor in the form of bony osteoderms, similar to turtles. Ankylosaurs were bulky quadrupeds, with short ...

, are reported from the Folkestone Formation of the Lower Greensand Group by Hadland ''et al'' (2021), representing the youngest known footprints of non-avian dinosaurs known from the United Kingdom. *A new dinosaur trackway is reported from the

Eumeralla Formation (Wattle Hill,

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

), by Romilio and Godfrey (2021), who report the presence of ornithopod and bird-like tracks, as well as a large theropod footprint possibly belonging to the ichnogenus Megalosauropus. * A study on the climate of the Lufeng area (

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

) during the

Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic� ...

, and on the relations between the global distribution of dinosaur fossils and climate during the Jurassic, is published by Shen ''et al.'' (2021). * A study on the relationships between diet, tooth complexity and tooth replacement rates in

Late Jurassic The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans the geologic time scale, geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic stratum, strata.Owen ...

dinosaurs is published by Melstrom, Chiappe & Smith (2021). * Description of the fossil material of a tyrannosauroid theropod and an early member of the family Hadrosauridae from the Upper Cretaceous Merchantville Formation (

Delaware Delaware ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic and South Atlantic states, South Atlantic regions of the United States. It borders Maryland to its south and west, Pennsylvania to its north, New Jersey ...

and

New Jersey New Jersey is a U.S. state, state located in both the Mid-Atlantic States, Mid-Atlantic and Northeastern United States, Northeastern regions of the United States. Located at the geographic hub of the urban area, heavily urbanized Northeas ...

, United States), possibly representing new taxa, and a study on the phylogenetic affinities of these dinosaurs is published by Brownstein (2021). * Druckenmiller ''et al.'' (2021) report the discovery of a diverse assemblage of herbivorous and carnivorous non-avian dinosaurs, including

perinatal Prenatal development () involves the development of the embryo and of the fetus during a viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal deve ...

and very young specimens, from the Upper Cretaceous

Prince Creek Formation The Prince Creek Formation is a geological Formation (geology), formation in Alaska with strata dating to the Late Campanian stage of the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.Weishamp ...

(

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

, United States), and interpret this finding as indicating that most, if not all, dinosaurs from this assemblage were nonmigratory year-round Arctic residents. * A study on the distribution of dinosaurs across the latest Cretaceous of North America is published by García-Girón ''et al.'' (2021). * A study aiming to determine whether plant-eating dinosaurs could have moved seeds long distances is published by Perry (2021). * Dinosaur tracks with elongated

metatarsal The metatarsal bones or metatarsus (: metatarsi) are a group of five long bones in the midfoot, located between the tarsal bones (which form the heel and the ankle) and the phalanges ( toes). Lacking individual names, the metatarsal bones are ...

marks and superficially human-like appearance are interpreted by Lallensack, Farlow & Falkingham (2021) as more likely to be caused by deep penetrations of the foot in soft sediment than by a

plantigrade 151px, Portion of a human skeleton, showing plantigrade habit In terrestrial animals, plantigrade locomotion means walking with the toes and metatarsals flat on the ground. It is one of three forms of locomotion adopted by terrestrial mammals. ...

mode of locomotion. * A study on changes of diversity of dinosaurs belonging to the families

Ankylosauridae Ankylosauridae () is a family of armored dinosaurs within Ankylosauria, and is the sister group to Nodosauridae. The oldest known ankylosaurids date to around 122 million years ago and went extinct 66 million years ago during the Cretaceous–Pal ...

Ceratopsidae Ceratopsidae (sometimes spelled Ceratopidae) is a family of ceratopsian dinosaurs including ''Triceratops'', ''Centrosaurus'', and ''Styracosaurus''. All known species were quadrupedal herbivores from the Upper Cretaceous. All but one species are k ...

Hadrosauridae Hadrosaurids (), also hadrosaurs or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod fam ...

Dromaeosauridae Dromaeosauridae () is a family of feathered coelurosaurian theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from ...

Troodontidae Troodontidae is a clade of bird-like theropod dinosaurs from the Late Jurassic to Late Cretaceous. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinos ...

and

Tyrannosauridae Tyrannosauridae (or tyrannosaurids, meaning "tyrant lizards") is a family of coelurosaurian theropod dinosaurs that comprises two subfamilies containing up to fifteen genera, including the eponymous ''Tyrannosaurus''. The exact number of genera ...

during the Late Cretaceous is published by Condamine ''et al.'' (2021), who interpret their findings as indicative of a decline of non-avian dinosaur diversity during the last 10 million years of the Cretaceous period, and attempt to determine possible causes of this decline. * The study published by Bonsor ''et al.'' (2020), aiming to determine whether non-avian dinosaurs were in long-term decline prior to the Cretaceous–Paleogene extinction event, is criticized by Sakamoto, Benton & Venditti (2021). * A study on a dinosaur nesting site preserved in the

Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cret ...

Wido Volcanics ( Wi Island,

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and t ...

) is published by Kim ''et al.'' (2021; final version published in 2022), providing new information on how these dinosaurs chose their nesting sites.

Saurischian research

* New fossil material of theropod and sauropod dinosaurs, including a caudal vertebra with

pneumatic Pneumatics (from Greek 'wind, breath') is the use of gas or pressurized air in mechanical systems. Pneumatic systems used in Industrial sector, industry are commonly powered by compressed air or compressed inert gases. A centrally located a ...

internal structures rarely observed outside Late Cretaceous South American saltasaurines, is described from the

Quseir Formation (

Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...

) by Salem ''et al.'' (2021). * Evidence indicating that some mid-sized dendroolithid eggs were laid by a therizinosauroid theropod is presented by Kundrát & Cruickshank (2021), who also report the discovery of putative embryonic remains (possibly of a

titanosaur Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thr ...

sauropod) in a faveoloolithid egg. * Putative large-sized sauropodomorph specimen from the

strata at the 'Cerro da Alemoa' locality (southern

) is reinterpreted as a herrerasaurid specimen (the largest dinosaur reported from the Candelária Sequence to date) by Garcia ''et al.'' (2021). * Putative tracks of a large-bodied predatory dinosaur from the Upper Triassic Blackstone Formation (

) are reinterpreted by Romilio ''et al.'' (2021) as sharing characteristics with the sauropodomorph

ichnogenus An ichnotaxon (plural ichnotaxa) is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. ''Ichnotaxon'' comes from the Ancient Greek (''íchnos'') meaning "track" and English , itself derived from ...

'' Evazoum'', and possibly representing the first evidence of basal sauropodomorph dinosaurs from Australia.

Theropod research

* A study aiming to determine whether the knowledge of patterns of species abundance and clade diversity in theropod dinosaurs is significantly impacted by the diagnosability of their fossils is published by Cashmore,

Butler A butler is a person who works in a house serving and is a domestic worker in a large household. In great houses, the household is sometimes divided into departments, with the butler in charge of the dining room, wine cellar, and pantries, pantr ...

& Maidment (2021). * A study on the evolution of vision and hearing modalities in theropod dinosaurs is published by Choiniere ''et al.'' (2021), who interpret their findings as indicative of early evolution of nocturnal predation in alvarezsauroid theropods. * A study on changes of feeding mechanics of theropods throughout their evolutionary history is published by Ma ''et al.'' (2021). * Bishop ''et al.'' (2021) create three-dimensional simulations of gait in ''

Coelophysis ''Coelophysis'' ( Traditional English pronunciation of Latin, traditionally; or , as heard more commonly in recent decades) is a genus of coelophysid Theropoda, theropod dinosaur that lived Approximation, approximately 215 to 201.4 million y ...

bauri'', and interpret their findings as indicative of a crucial and dynamic role of the tail in the locomotion of this theropod. * A vertebra of a non- coelophysoid, non- averostran neotheropod which may be 15 million years older than ''

Dilophosaurus ''Dilophosaurus'' ( ) is a genus of theropod dinosaurs that lived in what is now North America during the Early Jurassic, about 186 million years ago. Three skeletons were discovered in northern Arizona in 1940, and the two best preserv ...

wetherilli'' is described from the Lower Jurassic (

Hettangian The Hettangian is the earliest age and lowest stage of the Jurassic Period of the geologic timescale. It spans the time between 201.3 ± 0.2 Ma and 199.3 ± 0.3 Ma (million years ago). The Hettangian follows the Rhaetian (part of the Triass ...

) Whitmore Point Member of the Moenave Formation (

, United States) by Marsh ''et al.'' (2021), who interpret this finding as indicating that not all contemporaneous theropod traces were made by coelophysoids. * McMenamin (2021) describes a humerus of a neotheropod from the Portland Formation of the Early Jurassic (Massachucetts, USA) older and larger than ''

'', and interpret it as a large piscovorous creature based on the locale's ecology. * An assemblage of over 100 theropod footprints of various size and

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

is described from the Lower Jurassic Fengjiahe Formation (China) by Li ''et al.'' (2021), representing the track site with the largest number of theropod footprints in

Yunnan Yunnan; is an inland Provinces of China, province in Southwestern China. The province spans approximately and has a population of 47.2 million (as of 2020). The capital of the province is Kunming. The province borders the Chinese provinces ...

reported to date. * New fossil material of ceratosaur theropods, probably representing one of the oldest known record of abelisaurids, is described from the Upper Jurassic Cañadón Calcáreo Formation (

) by Rauhut & Pol (2021). * A study on the skeletal anatomy and phylogenetic relationships of '' Xenotarsosaurus bonapartei'' is published by Ibiricu ''et al.'' (2021). * Two new furileusaurian abelisaurid specimens from the

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

Bajo de la Carpa Formation (Argentina), providing new information on the abundance of abelisaurids in this area and on variety of abelisaurid morphotypes that coexisted in the north of Argentine Patagonia during the Late Cretaceous, are described by Méndez ''et al.'' (2021; final version published in 2022). * Description of the preserved integument of ''

Carnotaurus ''Carnotaurus'' (; ) is a genus of Theropoda, theropod dinosaur that lived in South America during the Late Cretaceous period, probably sometime between 72 and 69 million years ago. The only species is ''Carnotaurus sastrei''. Known from a si ...

sastrei'' is published by Hendrickx & Bell (2021). * Revision of the phylogenetic affinities and evolutionary significance of ''

Saltriovenator ''Saltriovenator'' (meaning " Saltrio hunter") is a genus of ceratosaurian dinosaur that lived during the Sinemurian stage of the Early Jurassic in what is now Italy. The type and only species is ''Saltriovenator zanellai''; in the past, the sp ...

zanellai'' and '' Scipionyx samniticus'' is published by Cau (2021), who interprets his findings as raising doubts on the systematic status of theropod specimens assigned to the family

Compsognathidae Compsognathidae is a family of coelurosaurian theropod dinosaurs. Compsognathids were small carnivores, generally conservative in form, hailing from the Jurassic and Cretaceous Period (geology), Periods. The bird-like features of these species, a ...

, which might turn out to be immature individuals belonging to various lineages of large-bodied tetanurans, with the holotype specimen of ''S. samniticus'' possibly being an immature carcharodontosaurid. * Two trackways belonging to fast-running theropods (probably basal tetanurans) are described from the Lower Cretaceous Enciso Group (

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

) by Navarro-Lorbés ''et al.'' (2021), who present the speeds of locomotion calculated for both trackways, which are among the top speeds ever calculated for non-avian theropod tracks, and interpret one of the trackways as produced by a dinosaur with the ability to make and control substantial speed changes while running. *

Spinosaurid Spinosauridae (or spinosaurids) is a clade or Family (taxonomy), family of tetanuran theropod dinosaurs comprising ten to seventeen known genera. Spinosaurid fossils have been recovered worldwide, including Africa, Europe, South America, and Asia. ...

neck vertebrae distinct from known vertebrae of ''

Spinosaurus ''Spinosaurus'' (; ) is a genus of large spinosaurid theropod dinosaurs that lived in what now is North Africa during the Cenomanian faunal stage, stage of the Late Cretaceous Period (geology), period, about 100 to 94 annum, million year ...

aegyptiacus'' and exhibiting an unusual combination of positionally variable characters are described from the

Kem Kem Group The Kem Kem Group (commonly known as the Kem Kem beds) is a geological group (stratigraphy), group in the Kem Kem region of eastern Morocco, whose strata date back to the Cenomanian stage of the Late Cretaceous. Its strata are subdivided into two ...

(

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

) by McFeeters (2021), who interprets this finding as evidence of a greater degree of intraspecific variation in the vertebrae of ''S. aegyptiacus'' than previously recognized, or alternatively, evidence for the occurrence of two spinosaurid taxa in the Kem Kem Group. * Spinosaurid caudal vertebrae are described from the Lower Cretaceous Sao Khua Formation (

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

) by Samathi, Sander & Chanthasit (2021), who also reinterpret the putative ceratosaur '' Camarillasaurus cirugedae'' as a spinosaurid. * A study on the diversity of the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammals h ...

e shape in spinosaurids, an on its implications for the knowledge of the phylogenetic relationships of the spinosaurids, is published by Lacerda, Grillo & Romano (2021). * Hone & Holtz (2021) evaluate the evidence for the competing interpretations of the ecology of ''

'', and reject the interpretation of this theropod as a specialised aquatic pursuit predator. * Pahl and Ruedas (2021) suggest that carnosaurs like ''Allosaurus'' were primarily scavengers that fed on sauropod carcasses, which they consider to be analogous to

whale fall A whale fall occurs when the Carrion, carcass of a whale has fallen onto the ocean floor, typically at a depth greater than , putting them in the Bathyal zone, bathyal or abyssal zones. On the sea floor, these carcasses can create complex local ...

s; however, their conclusions are criticized by Kane ''et al.'' (2023) but later defended by Pahl and Ruehdas (2023). * A study on the

and

geochemistry Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the e ...

of a

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

and a

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

of a specimen or specimens of ''

Allosaurus ''Allosaurus'' ( ) is an extinct genus of theropod dinosaur that lived 155 to 145 million years ago during the Late Jurassic period ( Kimmeridgian to late Tithonian ages). The first fossil remains that could definitively be ascribed to th ...

fragilis'' from the Cleveland-Lloyd Dinosaur Quarry (

, United States), and on its implications for the knowledge of the growth strategy of this species, is published by Ferrante ''et al.'' (2021). * Caudal vertebra of a theropod with affinities to Carcharodontosauria is described from the Upper Jurassic Sergi Formation by Bandeira ''et al.'' (2021), representing the first unambiguous record of a dinosaur from the

reported to date. * A study on the phylogenetic affinities of putative carcharodontosaurid teeth from the Upper Cretaceous strata in northern and central Patagonia, and on their implications for the knowledge of the timing of extinction of carcharodontosaurids in South America, is published by Meso ''et al.'' (2021). * Description of new fossil material of '' Phuwiangvenator yaemniyomi'' from the Lower Cretaceous Sao Khua Formation (

), and a study on its implications for the knowledge of the early evolution of Megaraptora, is published by Samathi ''et al.'' (2021). * A study on the skeletal anatomy of '' Aerosteon riocoloradensis'' is published by Aranciaga Rolando ''et al.'' (2021). * Fragmentary specimens of tyrannosaurid theropods from the

Dinosaur Park Formation The Dinosaur Park Formation is the uppermost member of the Belly River Group (also known as the Judith River Group), a major geologic unit in southern Alberta. It was deposited during the Campanian stage of the Late Cretaceous, between about 7 ...

of the

Alberta Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

) in the collection of the San Diego Natural History Museum were described by Yun (2021). * Bones of tyrannosaurid theropods with extensive tooth marks matching the teeth of tyrannosaurids are described from the Upper Cretaceous of the

San Juan Basin The San Juan Basin is a geologic structural basin located near the Four Corners region of the Southwestern United States. The basin covers 7,500 square miles and resides in northwestern New Mexico, southwestern Colorado, and parts of Utah a ...

(northwestern

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

) by Dalman &

Lucas Lucas or LUCAS may refer to: People * Lucas (surname) * Lucas (given name) Arts and entertainment * Luca Family Singers, or the Lucas, a 19th-century African-American singing group * Lucas, a 1960s Swedish pop group formed by Janne Lucas Perss ...

(2021), who interpret this finding as evidence for cannibalistic behavior among tyrannosaurids. * Caneer, Moklestad & Lucas (2021) describe structures which are not readily assignable to any known

ichnotaxon An ichnotaxon (plural ichnotaxa) is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. ''Ichnotaxon'' comes from the Ancient Greek (''íchnos'') meaning "track" and English , itself derived from ...

from the Upper Cretaceous of the Raton Basin (New Mexico), and interpret them as one footprint and two forearm/hand prints probably produced by a large tyrannosaurid theropod standing up from a prone position. *

Perinatal Prenatal development () involves the development of the embryo and of the fetus during a viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal deve ...

tyrannosaurid bones and teeth are described from the Upper Cretaceous

Two Medicine Formation The Two Medicine Formation is a geological formation, or rock body, in northwestern Montana and southern Alberta that was deposited between 82.4 Ma and 74.4 Ma, during Campanian (Late Cretaceous) time. It crops out to the east of the Rocky Mountai ...

(

Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...

, United States) and Horseshoe Canyon Formation (

) by Funston ''et al.'' (2021), who evaluate the implications of these findings for the knowledge of the minimum hatchling size of tyrannosaurids, their nesting habits and development of their teeth. * A study on tyrannosaurid tracks from the Campanian Wapiti Formation (Alberta, Canada), evaluating the implications of these tracks for the knowledge of changes in pedal anatomy of tyrannosaurids during their

, is published by Enriquez ''et al.'' (2021). * Tyrannosaurid fossil material is described from the Blagoveshchensk and Kundur fossil localities (Amur Region,

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

) by Bolotsky, Ermatsans & Bolotsky (2021). * A study on possible causes of monopolization of large carnivore guilds in Asian and American dinosaur assemblages by tyrannosaurids in the latest Cretaceous is published by Holtz (2021). * A study on the morphology, frequency, and ontogeny of facial bite marks in tyrannosaurid specimens is published by Brown, Currie & Therrien (2021), who interpret the ontogenetic distribution of bite scars in the studied specimens as possible evidence of

agonistic behaviour Agonistic behaviour is any social behaviour related to fighting, which can include aggressive behaviour, but also threats, displays, retreats, placation, and conciliation. The term "agonistic behaviour" was first defined and used by J.P. Scott ...

associated with the onset of sexual maturity. * A study on changes of mandibular biomechanical properties and tooth morphology in ''

sarcophagus'' and '' Gorgosaurus libratus'' during their

is published by Therrien ''et al.'' (2021), who interpret their findings as indicating the occurrence of ontogenetic dietary shift in albertosaurine tyrannosaurids. * A study on the mechanical properties of the mandibles of tyrannosaurine tyrannosaurids representing different

ontogenetic Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the stu ...

stages (including small juvenile) is published by Rowe & Snively (2021). * New

bone bed A bone bed is any Geology, geological stratum or deposition (geology), deposit that contains bones of whatever kind. Inevitably, such deposits are Sedimentary rock, sedimentary in nature. Not a formal term, it tends to be used more to describe esp ...

containing at least four specimens of ''

Teratophoneus ''Teratophoneus'' ("monstrous murderer"; Greek: ''teras'', "monster" and ''phoneus'', "murderer") is a genus of Tyrannosaurinae, tyrannosaurine Theropoda, theropod dinosaur that lived during the late Campanian age of the Late Cretaceous period, ...

curriei'' or a related tyrannosaurid is described from the Campanian

Kaiparowits Formation The Kaiparowits Formation is a sedimentary geological formation, rock formation found in the Kaiparowits Plateau in Grand Staircase–Escalante National Monument, in the southern part of Utah in the western United States. It is over 2800 feet (8 ...

(

, United States) by Titus ''et al.'' (2021), who study the

taphonomy Taphonomy is the study of how organisms decay and become fossilized or preserved in the paleontological record. The term ''taphonomy'' (from Greek language, Greek , 'burial' and , 'law') was introduced to paleontology in 1940 by Soviet scientis ...

of this bone bed, and evaluate its implications for the knowledge whether known accumulations of tyrannosaurid specimens represent time-averaged or forced accumulations, or whether they are evidence of gregariousness of tyrannosaurids. * A metatarsal of juvenile tyrannosaurid theropod from the

of the

, possibly referable to '' Daspletosaurus torosus'' was described by Yun (2021). * A study on the anatomy of the braincases of two specimens of ''Daspletosaurus'' is published by Paulina Carabajal ''et al.'' (2021). * A study aiming to calculate population variables such as abundance at any one time, species persistence and total number of individuals that ever lived for ''

rex'' is published by Marshall ''et al.'' (2021); the study is subsequently criticized by Meiri (2022). * A study aiming to estimate the natural frequency of the vertical swaying of the tail and the preferred walking speed and step frequency of ''

Tyrannosaurus rex ''Tyrannosaurus'' () is a genus of large theropoda, theropod dinosaur. The type species ''Tyrannosaurus rex'' ( meaning 'king' in Latin), often shortened to ''T. rex'' or colloquially t-rex, is one of the best represented theropods. It live ...

'' is published by van Bijlert, van Soest & Schulp (2021). * A study on the morphology of the neurovascular canal in the dentary of ''Tyrannosaurus rex'' is published by Kawabe & Hattori (2021). * A study attempting to determine bite force of a juvenile ''Tyrannosaurus rex'', based on mechanical tests designed to replicate bite marks attributed to juvenile specimens of this species, is published by Peterson, Tseng & Brink (2021). * A study on the taphonomic and geochemical history of the ''Tyrannosaurus rex'' specimen MOR 1125 is published by Ullmann ''et al.'' (2021). * A study on the anatomy of the postcranial skeleton and on the phylogenetic relationships of '' Pelecanimimus polyodon'' is published by Cuesta ''et al.'' (2021), who name a new clade Macrocheiriformes, defined as ''Pelecanimimus'' and all derived ornithomimosaurs. * New ornithomimid fossil material, providing new information on the distal tarsal morphology in ornithomimids, is described from the

(

, United States) by Nottrodt & Farke (2021). * A study on pelvic musculature in non-avian

maniraptora Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to ''Ornithomimus velox''. It contains the major subgroups Avialae, Dromaeosauridae, Troodontidae, ...

ns is published by Rhodes, Henderson & Currie (2021). * A study on the neuroanatomy of a new alvarezsauroid skeleton in the collection of the Henan Geological Museum (China) is published by Agnolín ''et al.'' (2021). *A study on the skeletal anatomy, probable musculature and likely function of tails of alvarezsaurian theropods is published by Meso ''et al.'' (2021). * A study on growth strategies and body miniaturization in the evolutionary history of alvarezsauroid theropods is published by Qin ''et al.'' (2021). * A study on the osteology of ''

Fukuivenator ''Fukuivenator'' ("hunter of Fukui Prefecture") is an extinct genus of maniraptoran theropod dinosaur from the Early Cretaceous of Japan. Discovery and naming The type species ''Fukuivenator paradoxus'' was named and described in 2016 by Yoi ...

paradoxus'' is published by Hattori ''et al.'' (2021), who described previously undescribed elements and reinterpret this genus as a basal therizinosaur. * A study on the anatomy of the postcranial skeleton of ''

Beipiaosaurus ''Beipiaosaurus'' is a genus of Therizinosauroidea, therizinosauroid theropod dinosaurs that lived in China during the Early Cretaceous in the Yixian Formation. The first remains were found in 1996 and formally described in 1999. Before the disc ...

inexpectus'' is published by Liao ''et al.'' (2021). * Reevaluation of putative blood cells preserved in the

specimen of ''Beipiaosaurus inexpectus'' is published by Korneisel ''et al.'' (2021), who interpret putative blood cells as more likely to be diagenetic structures. * Reconstructions of the muscular system of the hindlimb, forelimb and the

shoulder girdle The shoulder girdle or pectoral girdle is the set of bones in the appendicular skeleton which connects to the arm on each side. In humans, it consists of the clavicle and scapula; in those species with three bones in the shoulder, it consists o ...

of ''

Nothronychus ''Nothronychus'' (meaning "slothful claw") is a genus of therizinosaurid theropod dinosaurs that lived in North America during the Late Cretaceous period. The type species, ''Nothronychus mckinleyi'', was described by James Kirkland and Dougla ...

'' are presented by Smith (2021). * Zheng ''et al.'' (2021) study cellular and nuclear preservation in femoral articular cartilage of a specimen of '' Caudipteryx'' from the Yixian Formation (China). * Partial skeleton of '' Elmisaurus rarus'', preserving elements overlapping with known fossil material of '' Nomingia gobiensis'', is described from the Upper Cretaceous Nemegt Formation (

Mongolia Mongolia is a landlocked country in East Asia, bordered by Russia to the north and China to the south and southeast. It covers an area of , with a population of 3.5 million, making it the world's List of countries and dependencies by po ...

) by Funston ''et al.'' (2021), who interpret this specimen as indicating that ''N. gobiensis'' is likely a

of ''E. rarus''. * A study on the body mass of '' Anzu wyliei'' is published by Atkins-Weltman, Snively & O'Connor (2021). * A caenagnathid

is described from the

Mesaverde Formation History The Mesaverde Formation was first described by William Henry Holmes, W.H.Holmes in 1877 during the Hayden Survey. Holmes described the formation in the northern San Juan Basin as consisting of three units, which were a "Lower Escarpment ...

(

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

, United States; representing the first record of a caenagnathid from this formation) by Yun & Funston (2021), who evaluate the implications of this specimen for the knowledge whether reported differences in metatarsal morphology between ''"Macrophalangia"'' and '' Chirostenotes'' were merely

allometric Allometry (Ancient Greek "other", "measurement") is the study of the relationship of body size to shape, anatomy, physiology and behaviour, first outlined by Otto Snell in 1892, by D'Arcy Thompson in 1917 in ''On Growth and Form'' and by Juli ...

in nature, or whether they might represent phylogenetically informative variation. * An exceptionally preserved, articulated oviraptorid embryo, found inside an

elongatoolithid Elongatoolithidae is an oofamily of fossil eggs, representing the eggs of oviraptorosaurs (with the exception of the Bird, avian ''Ornitholithus''). They are known for their highly elongated shape. Elongatoolithids have been found in Europe, Asia ...

egg in a posture previously unrecognized in a non-avian dinosaur but sharing aspects of bird-like tucking postures, is described from the Upper Cretaceous Hekou Formation (China) by Xing ''et al.'' (2021); however, the conclusions of the authors are subsequently contested by Deeming & Kundrát (2022), who argue that this specimen was not close to hatching, and that the positioning of its head relative to its body cannot bear any relationship to hatching position of this animal. * Cau ''et al.'' (2021) report the identification of additional elements of the pectoral apparatus of the

specimen of '' Halszkaraptor escuilliei'', including the furcula, and evaluate its implications for the knowledge of the evolution of the avian furcula. * A study on the anatomy of the skeleton of '' Unenlagia comahuensis'' is published by Novas ''et al.'' (2021). * A study on the vertebral pneumaticity in ''Unenlagia comahuensis'' is published by Gianechini & Zurriaguz (2021). * Description of a new

troodontid Troodontidae is a clade of bird-like theropod dinosaurs from the Late Jurassic to Late Cretaceous. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinos ...

specimen from the Upper Cretaceous Wulansuhai Formation (China), and a study on the phylogenetic relationships and evolutionary history of the Late Cretaceous troodontids, is published by Wang ''et al.'' (2021). *A unique troodontid nest is described by Maipig ''et al.'' (2021), preserving a unique spiral pattern of eggs embedded vertically into substrate. * Multi-individual aggregates of mammal skeletons are described from the Upper Cretaceous

(

, United States) by Freimuth ''et al.'' (2021), who interpret these aggregates as the oldest known mammal-bearing regurgitalites, probably produced by '' Troodon formosus''. * A study on the anatomy and phylogenetic relationships of ''

Borogovia ''Borogovia'' is a troodontid theropod dinosaur genus which lived during the Late Cretaceous Period, in what is now Mongolia. It contains one species, ''Borogovia gracilicrus.'' Discovery and naming In 1971, a Polish-Mongolian expedition ...

gracilicrus'' is published by Cau & Madzia (2021). * Brown, Tanke & Hone (2021) describe a hadrosaurid bone from the

(

) preserved with bite marks produced by a small- to medium-sized theropod dinosaur, deviating from the majority of known theropod tooth marks and indicative of a behavior similar to mammalian gnawing. * Revision of the biodiversity of theropods from the Dinosaur Park Formation is published by Cullen ''et al.'' (2021). * Exquisitely preserved, ornamented partial eggs with theropod affinities, representing some of the smallest Mesozoic eggs reported to date, are described from the Campanian

(

, United States) by Oser ''et al.'' (2021), who name a new ootaxon '' Stillatuberoolithus storrsi''. * Sennikov (2021) conclude that therizinosaurids had a plantigrade stance based on their overall foot anatomy and reanalysis of the ichnogenus '' Macropodosaurus'', and reinterpret the ichnotaxon '' Batrachopus grandis'' from the Lower Cretaceous Jinju Formation and Haman Formation (

), formerly suggested to be made by bipedal

crocodylomorph Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. Extinct crocodylomorphs were considerably mor ...

s, as probable therizinosaur tracks based on comparison with ''Macropodosaurus''.

Sauropodomorph research

* Review of the diversity and composition of South American

sauropodomorph Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had lo ...

faunas throughout the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch a ...

is published by Pol ''et al.'' (2021). * A study on the evolution of the

olfactory system The olfactory system, is the sensory nervous system, sensory system used for the sense of smell (olfaction). Olfaction is one of the special senses directly associated with specific organs. Most mammals and reptiles have a main olfactory system ...

in sauropodomorph dinosaurs, as indicated by the ratio between the size of the

olfactory bulb The olfactory bulb (Latin: ''bulbus olfactorius'') is a neural structure of the vertebrate forebrain involved in olfaction, the sense of smell. It sends olfactory information to be further processed in the amygdala, the orbitofrontal cortex (OF ...

s and

cerebral hemisphere The vertebrate cerebrum (brain) is formed by two cerebral hemispheres that are separated by a groove, the longitudinal fissure. The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres ...

s in sauropodomorph endocasts, is published by Müller (2021). * A study on the timing of the earliest occurrence of Triassic sauropodomorphs in their northernmost range ( Fleming Fjord Formation,

Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...

), and on possible relationship between

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

s and early sauropodomorph dispersal to the temperate belt of the Northern Hemisphere, is published by Kent & Clemmensen (2021). * Probable tracks of large sauropodomorphs dinosaurs, potentially representing the largest known tracks belonging to the ichnogenus '' Eosauropus'' reported to date, are described from the Upper Triassic (likely

Rhaetian The Rhaetian is the latest age (geology), age of the Triassic period (geology), Period (in geochronology) or the uppermost stage (stratigraphy), stage of the Triassic system (stratigraphy), System (in chronostratigraphy). It was preceded by the N ...

) Blue Anchor Formation (Penarth, south Wales,

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

) by Falkingham ''et al.'' (2021). * A study on the evolution of the morphological diversity of sauropodomorph dinosaurs is published by Apaldetti ''et al.'' (2021). * New skull material of ''

Plateosaurus ''Plateosaurus'' (probably meaning "broad lizard", often mistranslated as "flat lizard") is a genus of plateosaurid dinosaur that lived during the Late Triassic period, around 214 to 204 million years ago, in what is now Central and Northern Eu ...

'', including the first two juvenile skulls of members of this genus, is described from the locality of Frick (

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

) by Lallensack ''et al.'' (2021), who attempt to determine whether the locality of Frick and German localities of Trossingen and Halberstadt contain specimens of ''Plateosaurus'' belonging to a single species. * A study on the skeletal growth during the

in ''

Massospondylus ''Massospondylus'' ( ) is a genus of sauropodomorph dinosaur from the Early Jurassic of southern Africa. It was described by Sir Richard Owen in 1854 from remains discovered in South Africa, and is thus one of the first dinosaurs to have been ...

carinatus'' is published by Chapelle, Botha & Choiniere (2021). * A study on the age of the fossil material of '' Yunnanosaurus youngi'' is published by Ren ''et al.'' (2021). *A study on the cranial anatomy of ''Anchisaurus polyzelus'' and the development of cranial characters in sauropodomorph ontogeny is published by Fabbri ''et al.'' (2021) * An assemblage including over 100 eggs and skeletal specimens of 80 specimens of '' Mussaurus patagonicus'', ranging from embryos to fully-grown adults, is described from the Laguna Colorada Formation (

) by Pol ''et al.'' (2021), who assign an

(

Sinemurian In the geologic timescale, the Sinemurian is an age (geology), age and stage (stratigraphy), stage in the Early Jurassic, Early or Lower Jurassic epoch (geology), Epoch or series (stratigraphy), Series. It spans the time between 199.5 ±0.3 annu ...

) maximum age for the ''Mussaurus'' bearing sediments, and interpret this assemblage as likely evidence of colonial nesting habits, presence of social cohesion throughout the different stages of the lifespan, and age-based social partitioning within a herd structure in ''Mussaurus''. * An extensive Late Jurassic sauropod tracksite, preserving the longest continuous sequence of sauropod pes prints reported to date and representing a rare record of a >180° turn made by the sauropod trackmaker to completely change direction and cross its own trackway, is described from a high altitude locality near Ouray (

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

, United States) by Goodell ''et al.'' (2021). * A study on the anatomy of the

axial skeleton The axial skeleton is the core part of the endoskeleton made of the bones of the head and trunk of vertebrates. In the human skeleton, it consists of 80 bones and is composed of the skull (28 bones, including the cranium, mandible and the midd ...

of ''

Bagualia ''Bagualia'' (meaning "wild horse"), is an extinct genus of Eusauropoda, eusauropod dinosaur, from the Early Jurassic (Middle Toarcian) Epoch in what is now the Chubut Province of Argentina. The type species, ''B. alba'', was formally described ...

alba'' is published by Gomez, Carballido & Pol (2021). * New fossil material of ''

Shunosaurus ''Shunosaurus'', meaning "Lizard from Sichuan", is a genus of sauropod dinosaur from Late Jurassic ( Oxfordian) beds in Sichuan Province in China, from 161 to 157 Million years ago. The name derives from "Shu", an ancient name for the Sichuan pr ...

'', providing new information on the development of the skeleton of this sauropod during its

, is described from the

Middle Jurassic The Middle Jurassic is the second Epoch (geology), epoch of the Jurassic Period (geology), Period. It lasted from about 174.1 to 161.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relativel ...

Shaximiao Formation The Shaximiao Formation () is a Middle to Late Jurassic aged geological formation in Sichuan, China, most notable for the wealth of dinosaurs fossils that have been excavated from its strata. The Shaximiao Formation is exposed in and around the ...

(China) by Ma ''et al.'' (2021). * A study on the skeletal anatomy of the

of '' Patagosaurus fariasi'' is published by Holwerda, Rauhut & Pol (2021). * A new specimen of '' Haplocanthosaurus'' with expanded neural canals is described by Wedel ''et al.'' (2021). * A study on the anatomy and phylogenetic relationships of '' Amphicoelias altus'' is published by Mannion, Tschopp & Whitlock (2021). * The paleohistology of two dicraeosaurids from the La Amarga Formation (

) is studied by Winholdz and Cerda (2021), who find that the holotype specimen of '' Amargatitanis macni'' belonged to a more mature individual than the holotype of ''

Amargasaurus ''Amargasaurus'' (; "La Amarga lizard") is a genus of sauropod dinosaur from the Early Cretaceous epoch (geology), epoch (129.4–122.46 Mya (unit), mya) of what is now Argentina. The only known skeleton was discovered in 1984 and is virtually ...

cazaui''. * Fossilized skin of a juvenile member of the genus '' Diplodocus'', providing evidence of new scale shapes and patterns never before seen in diplodocids, is described from the Mother's Day Quarry (

Bighorn Basin The Bighorn Basin is a plateau region and intermontane basin, approximately 100 miles (160 km) wide, in north-central Wyoming in the United States. It is bounded by the Absaroka Range on the west, the Pryor Mountains on the north, the Bigho ...

) by Gallagher, Poole & Schein (2021). * A study on the anatomy of the braincase of a diplodocid sauropod (possibly '' Leinkupal laticauda'') from the Lower Cretaceous Bajada Colorada Formation (Argentina) is published by Garderes ''et al.'' (2021; final version published in 2022). * Redescription of the anatomy of the braincase of '' Limaysaurus tessonei'' is published by Paulina-Carabajal & Calvo (2021). * A description of well preserved fossil material of '' Camarasaurus'', including an articulated, nearly-complete skull, and an analysis of variability within the genus based on cranial

allometry Allometry (Ancient Greek "other", "measurement") is the study of the relationship of body size to shape, anatomy, physiology and behaviour, first outlined by Otto Snell in 1892, by D'Arcy Thompson in 1917 in ''On Growth and Form'' and by Jul ...

trends is published by Woodruff ''et al.'' (2021). * Partial sauropod maxilla, possibly belonging to a brachiosaurid, is described from the Cretaceous (

Albian The Albian is both an age (geology), age of the geologic timescale and a stage (stratigraphy), stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early Cretaceous, Early/Lower Cretaceous epoch (geology), Epoch/s ...

–

) Longjing Formation (northeast China) by Liao ''et al.'' (2021). * Sauropod tracks probably produced by non-titanosaurian titanosauriforms are described from the Rupelo Formation (

) by Torcida Fernández-Baldor ''et al.'' (2021), who evaluate the paleoenvironmental and paleoecological implications of this finding, and name a new

'' Iniestapodus burgensis''. * A study on tooth replacement rates in early somphospondylans, as indicated by data from a dentary from the Lower Cretaceous (

Aptian The Aptian is an age (geology), age in the geologic timescale or a stage (stratigraphy), stage in the stratigraphic column. It is a subdivision of the Early Cretaceous, Early or Lower Cretaceous epoch (geology), Epoch or series (stratigraphy), S ...

–

) Haoling Formation (China), is published by Chang ''et al.'' (2021). * A study aiming to determine whether titanosaur

s could act as defensive structures is published by Silva Junior ''et al.'' (2021; final version published in 2022). * Description of the anatomy of the referred specimen of '' Diamantinasaurus matildae'' and a study on the phylogenetic relationships of this species is published by Poropat ''et al.'' (2021), who name a new clade Diamantinasauria, which includes it alongside '' Savannasaurus'' and ''

Sarmientosaurus ''Sarmientosaurus'' is a genus of titanosaurian sauropod dinosaur belonging to the Titanosauria. It lived in what is now South America, specifically Argentina, during the Upper Cretaceous Period (geology), Period about 95 million years ago. The ...

''. * Fossil material of a giant titanosaur sauropod, distinct from '' Andesaurus'' and probably exceeding ''

Patagotitan ''Patagotitan'' is a genus of titanosaurian sauropoda, sauropod dinosaur from the Cerro Barcino Formation in Chubut Province, Patagonia, Argentina. The genus contains a single species known from at least six young adult individuals, ''Patagotita ...

'' in size, is described from the

Candeleros Formation (

) by Otero ''et al.'' (2021). * Revision of known fossil material of '' Pellegrinisaurus powelli'' and a study on the skeletal anatomy, bone histology and phylogenetic relationships of this sauropod are published by Cerda ''et al.'' (2021). * New titanosaur remains, possibly belonging to a member of Colossosauria distinct from previously known taxa, are described from the Upper Cretaceous Portezuelo Formation (Argentina) by Bellardini ''et al.'' (2021). * A study on the anatomy of the axial skeleton of '' Rinconsaurus caudamirus'' is published by Pérez Moreno ''et al.'' (2021). *A study on the composition of several gastroliths from the Morrison are published by Malone, Strasser, Malone, D'Emic, Brown, and Craddock, who point to the differences between them and the surrounding rock and similarities to another site 1,000 km eastwards to suggest evidence of migration in sauropod dinosaurs. * Description of new fossil material and a study on the phylogenetic relationships of '' Tengrisaurus starkovi'' is published by Averianov, Sizov & Skutschas (2021). * Aureliano ''et al.'' (2021) report preservation of

histological Histology, also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissue (biology), tissues. Histology is the microscopic counterpart to gross anatomy, which looks at large ...

structure related to an avian-like air sac system in a vertebra of a saltasaurid titanosaur from the Upper Cretaceous São José do Rio Preto Formation (Bauru Group, Brazil). * Evidence of the preservation of nitrogen-bearing organic molecules (identified as

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

aceous moieties) in titanosaur eggshell from the Maastrichtian Lameta Formation (

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

) is presented by Dhiman ''et al.'' (2021). * A study on the stable isotope compositions of titanosaurian eggshells, bone and an associated tooth sampled in three Late Cretaceous nesting sites from La Rioja Province (Argentina), evaluating their implications for the knowledge of the body temperature of titanosaur sauropods, their diet, and the environmental conditions they needed reproduce, is published by Leuzinger ''et al.'' (2021).

Ornithischian research

* Revision of the phylogenetic nomenclature of ornithischian dinosaurs is published by Madzia ''et al.'' (2021), who name new clades Corythosauria, Euceratopsia, Saphornithischia, Panoplosaurini and Struthiosaurini. * New fossil material of ornithischians, including remains of basal euiguanodontian and hadrosaurid ornithopods and the southernmost record of ankylosaurs from South America reported to date, is described from the Upper Cretaceous (

–

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

) Chorrillo Formation (Argentina) by Rozadilla ''et al.'' (2021), who evaluate the implications of these fossils for the knowledge of the evolutionary history of ankylosaurs and hadrosaurids in South America. * A study on the Late Cretaceous ornithischian assemblage of western North America, aiming to examine the prediction that juveniles of large herbivores competitively excluded small herbivorous species, and that the small species that were able to coexist alongside the juveniles of larger species did so because of their unique occupation of niche space, is published by Wyenberg-Henzler, Patterson & Mallon (2021). * Radermacher ''et al.'' (2021) describe a new, fully articulated skeleton of '' Heterodontosaurus tucki'', preserving a suite of novel postcranial features unknown in any other ornithischian dinosaur, and evaluate the implications of this specimen for the knowledge of the evolution of ornithischian respiratory biology.

Thyreophoran research

* A study on the skeletal anatomy and bone

of '' Scutellosaurus lawleri'', providing new data on the morphology and new life reconstruction for this dinosaur, is published by Breeden '' et al.'' (2021). * A stegosaurian humerus is described from the Cañadón Calcáreo Formation (

) by Rauhut, Carballido & Pol (2021), extending the fossil record of Stegosauria to the Late Jurassic of South America. * A study on the morphology, macro- and microwear, and microanatomy of the stegosaur teeth from the Teete locality (Lower Cretaceous Batylykh Formation; Sakha,

), evaluating their implications for the knowledge of the paleobiology of the Teete stegosaur, is published by Skutschas ''et al.'' (2021). * The smallest stegosaur track reported to date, co-occurring with the tracks of larger individuals, is described from the Lower Cretaceous Tugulu Group (Xinjiang, China) by Xing ''et al.'' (2021). * The type locality and holotype of '' Dracopelta zbyszewskii'' are reinterpreted by Russo & Mateus (2021), who also chronicle the history of the holotype. * Riguetti ''et al.'' (2021) describe

nodosaurid Nodosauridae is a family of ankylosaurian dinosaurs known from the Late Jurassic to the Late Cretaceous periods in what is now Asia, Europe, North America, and possibly South America. While traditionally regarded as a monophyletic clade as the s ...

tracks from the

El Molino Formation (

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

), increasing known diversity of ankylosaur tracks from South America. * Several fragmentary skulls and skull elements of '' Hungarosaurus'', providing new information on the morphological diversity, development and possible function of the ornamentation of nodosaurid skulls, are described by Ősi ''et al.'' (2021). * A study on

dental microwear Dental microwear analysis is a method to infer diet and behavior in extinct animals, especially in fossil specimens. It has been used on a variety of taxa, including hominids, victoriapithecids, amphicyonids, canids, ursids, hyaenids, hyaenodont ...

and jaw movement of '' Jinyunpelta'', and on its implications for the knowledge of the evolution of the feeding mechanism of ankylosaurids, is published by Kubo ''et al.'' (2021). * Articulated postcranial skeleton of an indeterminate ankylosaurid dinosaur is described from the

Barun Goyot Formation The Baruungoyot Formation (also known as Barun Goyot) is a geological formation dating to the Late Cretaceous Period. It is located within and is widely represented in the Gobi Desert Basin, in the Ömnögovi Province of Mongolia. Descriptio ...

(

) by Park ''et al.'' (2021), who interpret this specimen as indicating that Asian ankylosaurids evolved rigid bodies with a reduced number of pedal

phalanges The phalanges (: phalanx ) are digit (anatomy), digital bones in the hands and foot, feet of most vertebrates. In primates, the Thumb, thumbs and Hallux, big toes have two phalanges while the other Digit (anatomy), digits have three phalanges. ...

, as well as the existence of at least two forms of flank armor in ankylosaurids, and discuss possible adaptations for digging in ankylosaurids.

Cerapod research

* A study on the skeletal anatomy and phylogenetic relationships of '' Haya griva'' is published by Barta & Norell (2021). * Duncan ''et al.'' (2021) describe

ornithopod Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (). They represent one of the most successful groups of herbivorous dinosaurs during the Cretaceous. The most primitive members of the group were bipedal and relatively sm ...

jaws from the Lower Cretaceous Eumeralla Formation (

), and evaluate the implications of these fossils for the knowledge of the diversity of Early Cretaceous ornithopods from this area. * A study on the anatomy of the manus of ''

Tenontosaurus ''Tenontosaurus'' ( ; ) is a genus of iguanodontian ornithopod dinosaur. It had an unusually long, broad tail, which like its back was stiffened with a network of bony tendons. The genus is known from the late Aptian to Albian ages of the Early ...

tilletti'' is published by Hunt, Cifelli & Davies (2021). * A study on the accumulated remains of '' Dysalotosaurus lettowvorbecki'' from the Upper Jurassic

Tendaguru Formation The Tendaguru Formation, or Tendaguru Beds are a highly List of fossiliferous stratigraphic units in Tanzania, fossiliferous Lithostratigraphy, formation and Lagerstätte located in the Lindi Region of southeastern Tanzania. The formation represe ...

(

) is published by Hübner ''et al.'' (2021), who interpret two large bonebeds as most likely resulting from two independent catastrophic mortality events. * A study on the anatomy of the braincase and probable brain size in '' Proa valdearinnoensis'' is published by Knoll ''et al.'' (2021). * A specimen of '' Gobihadros mongoliensis'' preserving features of cessation of growth, indicating that it reached the terminal size and advanced age, is described from the Upper Cretaceous Bayan Shireh Formation (

) by Słowiak ''et al.'' (2021), who diagnose this specimen as affected by

calcium pyrophosphate deposition disease Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease, also known as pseudogout and pyrophosphate arthropathy, is a rheumatologic disease which is thought to be secondary to abnormal accumulation of calcium pyrophosphate dihydrate c ...

, making it the first known non-avian dinosaur specimen affected with this disease. * Redescription of the anatomy and a study on the phylogenetic relationships of '' Lophorhothon atopus'', based on data from the

and from a new specimen, is published by Gates & Lamb (2021). * A study on the anatomy of the postcranial skeleton of '' Tanius sinensis'' is published by Borinder ''et al.'' (2021). * Description of new fossil material of ''

Tethyshadros ''Tethyshadros'' ("Tethys Ocean, Tethyan hadrosauroid") is a genus of Hadrosauroidea, hadrosauroid dinosaur from the Late Cretaceous (Campanian) Calcare di Aurisina (previously thought to come from the younger Liburnia Formation) of Trieste, Ita ...

insularis'' from the Villaggio del Pescatore fossil site (

), a study on the age of this site and on the phylogenetic affinities of ''T. insularis'', and a reevaluation of claims about the evolution of

insular dwarfism Insular dwarfism, a form of phyletic dwarfism, is the process and condition of large animals evolving or having a reduced body size when their population's range is limited to a small environment, primarily islands. This natural process is disti ...

in Late Cretaceous hadrosauroids, is published by Chiarenza ''et al.'' (2021). * Description of new fossil material of hadrosaurids from the Upper Cretaceous Lago Colhué Huapí Formation (

), and a study on the environment inhabited by these hadrosaurids and on the influence of paleoenvironmental conditions on South American hadrosaurid distribution, is published by Ibiricu ''et al.'' (2021). * Holland ''et al.'' (2021) describe an assemblage of late juvenile hadrosaurid specimens from the Spring Creek Bonebed (Alberta, Canada), representing the first record of lambeosaurines from the Wapiti Formation and possibly indicating that age segregation was a life history strategy among hadrosaurids. * Revision of the type material and a study on the phylogenetic affinities of '' Latirhinus uitstlani'' is published by Ramírez-Velasco, Espinosa-Arrubarrena & Alvarado-Ortega (2021); a study on the

of the skeletal elements in the

of ''L. uitstlani'' designated by the aforementioned authors, on the skeletal composition of the holotype, on the diagnostic utility of the characters used by Ramírez-Velasco, Espinosa-Arrubarrena & Alvarado-Ortega (2021) for referring other specimens to different hadrosaurid clades, and on the phylogenetic affinities of ''L. uitstlani'' is subsequently published by Serrano-Brañas & Prieto-Márquez (2021). *Redescription of ''

Parasaurolophus ''Parasaurolophus'' (; meaning "beside crested lizard" in reference to ''Saurolophus'') is a genus of hadrosaurid "duck-billed" dinosaur that lived in what is now western North America and possibly Asia during the Late Cretaceous period, a ...

cyrtocristatus'', based on data from a new skull from the

Fruitland Formation (

, United States), is published by Gates, Evans & Sertich (2021). * A study on the injuries of the

specimen of '' Bonapartesaurus rionegrensis'', and on their implications for the knowledge of its paleobiology, is published by Cruzado-Caballero ''et al.'' (2021). * Five new partial skulls of '' Maiasaura peeblesorum'', providing information on the acquisition of the crest and changes to the surrounding cranial elements during the

of this dinosaur, are described from the

(

, United States) by McFeeters, Evans & Maddin (2021). * A study aiming to determine the taxonomic validity of the species '' Sphaerotholus buchholtzae'' and ''S. edmontonensis'' is published by Woodruff ''et al.'' (2021). * Vinther, Nicholls & Kelly (2021) describe the first fossil cloacal vent in an exceptionally preserved non-avian dinosaur specimen (a specimen of ''

'' from the Early Cretaceous Jehol deposits of Liaoning, China). * A study on jaws and teeth of juvenile and adult specimens of ''

lujiatunensis'', aiming to determine whether this dinosaur underwent a dietary shift during its

, is published by Landi ''et al.'' (2021). * A study on the

changes in the femoral

of ''Psittacosaurus sibiricus'' is published by Skutschas ''et al.'' (2021). * A study on the whole-skull shape in a large sample of specimens of ''

Protoceratops ''Protoceratops'' (; ) is a genus of small protoceratopsid dinosaurs that lived in Asia during the Late Cretaceous, around 75 to 71 million years ago. The genus ''Protoceratops'' includes two species: ''P. andrewsi'' and the larger ''P. hellenik ...

andrewsi'' is published by Knapp, Knell & Hone (2021), who argue that the frill of ''P. andrewsi'' shows several characteristics consistent with a socio-sexual trait. * A study on the anatomy of a specimen of ''Protoceratops andrewsi'' from the Bayan Zag locality ( Djadochta Formation, Mongolia), interpreted as most likely to be a large immature female, and on its implications for explanation of the polymorphism in the fossil material attributed to ''P. andrewsi'' and for diagnosing ''P. andrewsi'' from vertebrae considering the age and sex of compared specimens, is published by Tereshchenko (2021). * Description of a skull of a subadult specimen of '' Einiosaurus procurvicornis'' from the

(

, United States), and a study on the implications of this specimen for the knowledge of the sequence and timing of development of primary cranial ornaments in eucentrosauran ceratopsids, is published by Wilson & Scannella (2021). * A study on the dentition of ''

Stegoceras ''Stegoceras'' is a genus of Pachycephalosauria, pachycephalosaurid (dome-headed) dinosaur that lived in what is now North America during the Late Cretaceous Period (geology), period, about 77.5 to 74 million years ago (mya). The first specim ...

validum'' and ''

Thescelosaurus ''Thescelosaurus'' ( ) is a genus of Ornithischia, ornithischian dinosaur that lived during the Late Cretaceous period (geology), period in western North America. It was named and described in 1913 by the Paleontology, paleontologist Charles W. G ...

neglectus'', and on its implications for the knowledge of the feeding behavior of these ornithischians, is published by Hudgins, Currie & Sullivan (2021). * A study on the biodiversity patterns of Late Cretaceous hadrosaurids and ceratopsids from the western interior of North America, evaluating whether the fossil record provides evidence of faunal provinciality of these dinosaurs, is published by Maidment ''et al.'' (2021).

Birds

New bird taxa

Avian research

* The study on the phylogenetic relationships and powered flight potential of early birds and their closest relatives published by Pei ''et al.'' (2020), arguing that the potential for powered flight evolved at least three times (once in birds and twice in dromaeosaurids), is criticized by Serrano & Chiappe (2021). * Review of the most relevant events in limb evolution across the dinosaur-bird transition and the origins of bird flight is published by Nebreda, Hernández Fernández & Marugán-Lobón (2021). * A study on the diversification rates of birds throughout their evolutionary history is published by Yu, Zhang & Xu (2021). * A study on the evolution of the brain in birds, based on data from extant and recently extinct birds, ''

Archaeopteryx ''Archaeopteryx'' (; ), sometimes referred to by its German name, "" ( ''Primeval Bird'') is a genus of bird-like dinosaurs. The name derives from the ancient Greek (''archaîos''), meaning "ancient", and (''ptéryx''), meaning "feather" ...

'' and non-avian coelurosaurian theropods, is published by Watanabe ''et al.'' (2021). * A study aiming to infer the diets of the last common ancestor of living birds, based on data from digestive system-related genes, is published by Wu (2021), who interprets his findings as indicative of a diet shift from carnivory to herbivory at the non-avian archosaur-to-bird transition, and evaluates possible implications of this diet shift for the evolution of early birds. * Review of methods used to determine diet in modern and fossil birds, evaluating their utility for determination of diets of Mesozoic birds, is published by Miller & Pittman (2021). * A study on patterns and modes of the evolution of skeletal morphology and limb proportions in Mesozoic birds is published by Wang ''et al.'' (2021). * A study on the variation in tooth crown shape of Mesozoic birds, and its implications for the knowledge of their diets, is published by Zhou ''et al.'' (2021). * A study on the impact of tooth loss on the diversification of Mesozoic birds is published by Brocklehurst & Field (2021), who find no evidence for a link between toothlessness and accelerated

cladogenesis Cladogenesis is an evolutionary splitting of a parent species into two distinct species, forming a clade. This event usually occurs when a few organisms end up in new, often distant areas or when environmental changes cause several extinctions, ...

, as well as no evidence for models whereby acquisitions of toothlessness among Mesozoic birds were driven by an overarching selective trend. * Review of the variability of bone

in basal members of

Avialae Avialae ("bird wings") is a clade containing the only living dinosaurs, the birds, and their closest relatives. It is usually defined as all theropod dinosaurs more closely related to birds (Aves) than to Deinonychosauria, deinonychosaurs, though ...

is published by Monfroy & Kundrát (2021). * A study on the

ecomorphology Ecomorphology or ecological morphology is the study of the relationship between the ecological, ecological role of an individual and its morphology (biology), morphological adaptations. The term "morphological" here is in the anatomical context. Bo ...

of extant and fossil birds, aiming to determine whether the ecologies of Mesozoic birds can be inferred on the basis of data from measurements of their forelimbs and hindlimbs, is published by Bell ''et al.'' (2021). * The study published by Kaye, Pittman & Wahl (2020), reporting evidence interpreted by the authors as indicative of the feather moulting in the Thermopolis specimen of ''

'', is criticized by Kiat ''et al.'' (2021). * A study on the cellular preservation in the calcified cartilage of specimens of '' Confuciusornis'' and ''

Yanornis ''Yanornis'' () is an extinct genus of fish-eating Early Cretaceous birds. Two species have been described, both from Liaoning province, China: ''Yanornis martini'', based on several fossils found in the 120-million-year-old Jiufotang Formation ...

'' from the Early Cretaceous Jehol biota (northeast China) is published by Bailleul & Zhou (2021). * A study on the nanostructures of the

melanosome A melanosome is an organelle found in animal cells and is the site for synthesis, storage and transport of melanin, the most common light-absorbing pigment found in the animal kingdom. Melanosomes are responsible for color and photoprotectio ...

s sampled from a specimen of '' Eoconfuciusornis'' from the Lower Cretaceous

Huajiying Formation The Huajiying Formation is a geological formation in Hebei, People's Republic of China. Known for its fossils including feathered dinosaurs, the age of the formation is uncertain. It may represent an early portion of the Jehol Biota, dating to som ...

(China) is published by Pan ''et al.'' (2021), who interpret their findings as evidence of brilliant iridescent plumage color in ''Eoconfuciusornis''. * A study on the

of the scapulocoracoid in ''Confuciusornis'' is published by Wu ''et al.'' (2021). * New enantiornithine specimen with a well-preserved skull, retaining the

plesiomorphic In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, an ...

dinosaurian palate and

diapsid Diapsids ("two arches") are a clade of sauropsids, distinguished from more primitive eureptiles by the presence of two holes, known as temporal fenestrae, in each side of their skulls. The earliest traditionally identified diapsids, the araeosc ...

temporal configurations indicative of an akinetic skull, is described from the Lower Cretaceous

Jiufotang Formation The Jiufotang Formation () is an Early Cretaceous geological formation in Chaoyang, Liaoning which has yielded fossils of feathered dinosaurs, primitive birds, pterosaurs, and other organisms (see Jehol Biota). It is a member of the Jehol group. T ...

(China) by Wang ''et al.'' (2021), who evaluate the implications of this specimen for the knowledge of the evolution of bird skulls. * A study on teeth replacement patterns in members of Enantiornithes, based on data from three specimens from the Cretaceous

(

), is published by Wu ''et al.'' (2021). * A study aiming to infer resting metabolic rates of '' Concornis'' and ''

Iberomesornis ''Iberomesornis'' ("Iberian intermediate bird") is a monotypic genus of enantiornithine bird of the Cretaceous of Spain. Discovery In 1985 the fossil of ''Iberomesornis'' was discovered by Armando Díaz Romeral in the Early Cretaceous Caliza ...

'' on the basis of data from bone histology is published by Cubo ''et al.'' (2021). * A study on the anatomy of the

quadrate bone The quadrate bone is a skull bone in most tetrapods, including amphibians, sauropsids ( reptiles, birds), and early synapsids. In most tetrapods, the quadrate bone connects to the quadratojugal and squamosal bones in the skull, and forms up ...

of '' Longipteryx chaoyangensis'', evaluating its possible functional implications, is published by Stidham & O'Connor (2021), who consider '' Camptodontornis yangi'' and '' Shengjingornis yangi'' as synonyms of ''Longipteryx''. * Description of a new bohaiornithid specimen from the Lower Cretaceous

(China), providing new information on the skull anatomy and teeth replacement pattern in bohaiornithids, and a study on the phylogenetic relationships of enantiornithines traditionally included in the family Bohaiornithidae, is published by Liu ''et al.'' (2021; final version published in 2022). * A study on the identity of purported

gastrolith A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract. Gastroliths in some species are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. In ...

s reported in a referred specimen of ''

Bohaiornis ''Bohaiornis'' is a genus of enantiornithean dinosaurs. Fossils have been found from the Lower Cretaceous Jiufotang Formation of western Liaoning, China. The only known species, ''Bohaiornis guoi'', was named by Dongyu Hu, Li Li, Lianhaim Hou an ...

guoi'' from the Early Cretaceous of China is published by Liu ''et al.'' (2021). * A study on the bone

and growth of the skeleton of '' Mirarce eatoni'' is published by Atterholt ''et al.'' (2021). * An almost complete juvenile specimen of '' Archaeorhynchus'' is described from the

(China) by Foth ''et al.'' (2021), who evaluate the implications of the anatomy of this specimen for the knowledge of the

development of Mesozoic birds. * A study on variations in bone growth and on the thermal regime of ''

martini'' is published by Monfroy ''et al.'' (2021). * Ju ''et al.'' (2021) revise the fossil material of '' Iteravis huchzermeyeri'' and '' Gansus zheni'', and consider these species to be

synonymous A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

. * A study on the bone histology of ''Gansus yumenensis'', and on its implications for the knowledge of the evolution of uninterrupted bone deposition in birds, is published by Monfroy ''et al.'' (2021). * A cervical vertebra of a member of Ornithuromorpha distinct from '' Gargantuavis'', representing the first fossil evidence of a giant bird from the late

of Europe reported to date, is described from Beranuy (Huesca,

) by Pérez-Pueyo ''et al.'' (2021). * Torres, Norell & Clarke (2021) describe a new specimen of '' Ichthyornis dispar'' from the

Niobrara Formation The Niobrara Formation , also called the Niobrara Chalk, is a geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the Late Cretaceous. It is com ...

(

Kansas Kansas ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the west. Kansas is named a ...

, United States), preserving a nearly complete skull, and evaluate the implications of the anatomy of this specimen for the knowledge of the evolution of birds and for the knowledge of probable reasons why birds survived the end-Cretaceous mass extinction. * New information on the anatomy of ''

Vegavis ''Vegavis'' is a genus of extinct bird that lived in Antarctica during the Maastrichtian stage of the Late Cretaceous. The type and only species is ''Vegavis iaai'', representing one of the earliest known crown group birds. Initially described ...

iaai'', based on data from the

specimen which was fully extracted from the sedimentary matrix, is presented by Acosta Hospitaleche & Worthy (2021). *

Mayr Mayr is a German surname. Notable people with the surname include: * Andrea Mayr (born 1979), Austrian female long-distance runner * Ernst Mayr (1904–2005), German American evolutionary biologist * Franz Xaver Mayr (1875–1965), Austrian gastro ...

& Zelenkov (2021) interpret eogruids and ergilornithids as representatives of the

stem group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

Struthioniformes Struthioniformes is an order of birds with only a single extant family, Struthionidae, containing the ostriches. Several other extinct families are known, spanning across the Northern Hemisphere, from the Early Eocene to the early Pliocene, incl ...

, based on data from new fossils from the late

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

. * A fossil ostrich specimen with exceptional soft-tissue preservation is described from the

Liushu Formation (Linxia Basin, China) by Li ''et al.'' (2021). * A

of a giant ostrich, significantly larger than the living

common ostrich The common ostrich (''Struthio camelus''), or simply ostrich, is a species of flightless bird native to certain areas of Africa. It is one of two extant species of ostriches, the only living members of the genus ''Struthio'' in the ratite group ...

, is described from the Pleistocene Nihewan Formation (

) by Buffetaut & Angst (2021), who assign it to ''

Pachystruthio ''Pachystruthio'' is a genus of extinct bird which lived in Eurasia from the Late Pliocene to the Middle Pleistocene. Its fossils have been found in Hungary, Greece Crimea, Georgia (country), Georgia, and China. The genus contains three species: ...

'' indet. and interpret this finding as evidence of wide geographical distribution of giant ostriches in the Early Pleistocene of Eurasia. * A study on the phylogenetic relationships and evolutionary history of extant and fossil

tinamou Tinamous () are members of the order Tinamiformes (), and family Tinamidae (), divided into two distinct subfamily, subfamilies, containing 46 species found in Mexico, Central America, and South America. The word "tinamou" comes from the Carib la ...

s is published by Almeida ''et al.'' (2021). * A mid-

Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

deposit attributed to the bush moa is reported from southern

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

by Wood ''et al.'' (2021), who evaluate the implications of this finding for the knowledge of the diet and ecology of this moa. * A study comparing egg size and volume in extinct island emus and in mainland emu, aiming to determine egg size in relation to body size in island emus and their breeding strategy, is published by Hume & Robertson (2021). * A study on the phylogenetic relationships of '' Brontornis burmeisteri'' is published by Agnolin (2021), who interprets this taxon as a member of Galloanserae. * Reexamination of specimens of '' Omorhamphus storchii'' and '' Gastornis parisiensis'' alleged to preserve alveoli for teeth is published by Louchart ''et al.'' (2021), who reject claims of presence of teeth in gastornithids. * A study on the morphology of the dromornithid brain, based on data from dromornithid endocast material spanning from the late

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

to the late

, is published by Handley & Worthy (2021). * A study on the bone histology, growth dynamics and life history of '' Genyornis newtoni'' is published by Chinsamy & Worthy (2021). * A study on bone pathologies in specimens of ''Genyornis newtoni'' from the Lake Callabonna fossil deposit (

) is published by McInerney ''et al.'' (2021), who interpret the studied specimens as likely affected by

osteomyelitis Osteomyelitis (OM) is the infectious inflammation of bone marrow. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The feet, spine, and hips are the most commonly involved bones in adults. The cause is ...

. * Partial humerus of a

coscoroba swan The coscoroba swan (''Coscoroba coscoroba'') is a species of waterfowl in the subfamily Anserinae of the family Anatidae.HBW and BirdLife International (2021) Handbook of the Birds of the World and BirdLife International digital checklist of the ...

is described from the Upper Pleistocene Capellanía Formation (Argentina) by Vezzosi ''et al.'' (2021), who evaluate the implications of this finding for the knowledge of the knowledge of the dispersal of Neotropical swans during the Pleistocene. * Partial skull of a pheasant-sized galliform land bird of uncertain phylogenetic placement is described from the latest Eocene or earliest Oligocene Jansen Creek Member of the Makah Formation ( Washington, United States) by Mayr, Goedert & Rabenstein (2021), who report that this specimen preserves a foramen in the temporal region that enabled the vena profunda to enter the braincase, and interpret this foramen as a previously unnoticed cranial

autapomorphy In phylogenetics, an autapomorphy is a distinctive feature, known as a Synapomorphy, derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or Outgroup (cladistics), outgroup taxa, not ...

of galliforms. * Redescription of '' Columba congi'' is published by Shen, Stidham & Li (2021). * Description of new fossil material of '' Scandiavis mikkelseni'' from the Eocene

Fur Formation The Fur Formation is a marine geological formation of Ypresian ( Lower Eocene Epoch, c. 56.0-54.5 Ma) age which crops out in the Limfjord region of northern Denmark from Silstrup via Mors and Fur to Ertebølle, and can be seen in many cliffs and ...

(

Denmark Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...

), providing new information on the brain anatomy of this bird, and a study on the phylogenetic affinities of ''Scandiavis'' is published by Heingård ''et al.'' (2021). * Oswald ''et al.'' (2021) recover a nearly complete mitochondrial genome of the Haitian cave rail ('' Nesotrochis steganinos)'' from fossils, and find this bird to be a relative of the families

Sarothruridae Sarothruridae is a family of small- to medium-sized ground-living birds found mostly in Madagascar and sub-Saharan Africa, with the genus ''Rallicula'' being restricted to New Guinea and the Moluccas. The species in this family were once consider ...

and Aptornithidae rather than a rallid as previously thought. * A study reconstructing the wing musculature of the

great auk The great auk (''Pinguinus impennis''), also known as the penguin or garefowl, is an Extinction, extinct species of flightless bird, flightless auk, alcid that first appeared around 400,000 years ago and Bird extinction, became extinct in the ...

and ''

Mancalla ''Mancalla'' is an extinct genus of prehistoric flightless alcids that lived on the Pacific coast of today's California and Mexico during the Late Miocene to Early Pliocene Early may refer to: Places in the United States * Early, Iowa, a cit ...

'' is published by Watanabe, Field & Matsuoka (2021). * New fossil material of plotopterids, resembling bones of '' Olympidytes'' (which was previously considered

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to North America), is described from the Eocene to Oligocene Itanoura and Kakinoura formations (

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

) by Mori & Miyata (2021), who interpret these fossils as indicating that early diversity of this family in Japan was higher than previously thought. * New fossil material of plotopterids is described from Washington by Mayr & Goedert (2021), who also revise the species ''Tonsala buchanani'' and transfer it to the genus '' Klallamornis''. * A

carpometacarpus The carpometacarpus is a bone found in the hands of birds. It results from the fusion of the carpal and metacarpal bone, and is essentially a single fused bone between the wrist and the knuckles. It is a smallish bone in most birds, generally fla ...

of a petrel, potentially representing a new genus and species, is described from the

Gaiman Formation (Argentina) by Piro & Acosta Hospitaleche (2021). * A study on the anatomy and pneumaticity of the skull and on the paleoneurology of the fossil banded penguin ''Spheniscus urbinai'' is published by Acosta Hospitaleche, Paulina-Carabajal & Yury-Yáñez (2021). * A study on the new referred material of '' Dryornis pampeanus'' from the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58cathartiform reported to date. * The first unequivocal fossil material of

teratorns Teratornithidae is an extinct family (biology), family of very large Bird of prey, birds of prey that lived in North and South America from the Oligocene, Late Oligocene to Pleistocene, Late Pleistocene. They include some of the largest known fly ...

from the Pleistocene of South America is described from four fossiliferous localities of Central Argentina by Cenizo ''et al.'' (2021), who evaluate the implications of these fossils for the knowledge of the evolutionary history of teratorns, and update the taxonomy of the family. * A study on the feeding capabilities and behaviour of the

Haast's eagle Haast's eagle (''Hieraaetus moorei'') is an Extinction, extinct species of eagle that lived in the South Island of New Zealand, commonly accepted to be the of Māori mythology.

is published by van Heteren ''et al.'' (2021). * Description of a partial skeleton of a member of the genus ''

Septencoracias ''Septencoracias'' is an extinct genus of bird related to modern Coraciidae, rollers and other Coraciiformes such as kingfishers, bee-eaters, motmots, and tody, todies. It contains two species, ''Septencoracias morsensis'' described in 2016, and ...

'' from the Eocene

London Clay The London Clay Formation is a Sediment#Shores and shallow seas, marine formation (geology), geological formation of Ypresian (early Eocene Epoch, c. 54-50 million years ago) age which outcrop, crops out in the southeast of England. The London C ...

(

), belonging or related to the species ''S. morsensis'', and a study on the phylogenetic affinities and likely ecology of this bird is published by Mayr (2021). * Redescription of the type specimen of '' Macrornis tanaupus'' from the Eocene Totland Bay Formation (

Hampshire Hampshire (, ; abbreviated to Hants.) is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Berkshire to the north, Surrey and West Sussex to the east, the Isle of Wight across the Solent to the south, ...

) is published by Buffetaut & Angst (2021), who interpret this fossil as a partial

tibiotarsus The tibiotarsus is the large bone between the femur and the tarsometatarsus in the leg of a bird. It is the fusion of the proximal part of the tarsus with the tibia. A similar structure also occurred in the Mesozoic Heterodontosauridae. These ...

of a large terrestrial bird, possibly a phorusrhacid. * A review of the knowledge of phorusrhacid skull anatomy is presented by Degrange (2021). * Mayr, De Pietri & Scofield (2021) describe new fossil material of birds from the Eocene Nanjemoy Formation (

Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

, United States), including the first representatives of the families Messelasturidae, Psittacopedidae and Zygodactylidae from this formation. * Two passerine specimens representing different size classes (thrush-sized and sylvid-sized), providing information on skeletal element proportions of the middle Miocene passerines, are described from the Miocene of

Austria Austria, formally the Republic of Austria, is a landlocked country in Central Europe, lying in the Eastern Alps. It is a federation of nine Federal states of Austria, states, of which the capital Vienna is the List of largest cities in Aust ...

by Happ ''et al.'' (2021). * A distal end of the left tarsometatarsus of a phasianid, which represents the first avian fossil record of

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia. The main geography of Taiwan, island of Taiwan, also known as ''Formosa'', lies between the East China Sea, East and South China Seas in the northwestern Pacific Ocea ...

, is described from the

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

Chiting Formation (

Tainan Tainan (), officially Tainan City, is a Special municipality (Taiwan), special municipality in southern Taiwan, facing the Taiwan Strait on its western coast. Tainan is the oldest city on the island and commonly called the "Taiwan Prefecture, ...

, Taiwan) by Tsai & Mayr (2021). * A study on the mechanics of egg incubation by giant extinct birds is published by Yen et al. (2021). * Revision of the fossil material of birds from Miocene localities in the Iberian Peninsula is published by Sánchez-Marco (2021). * Ramírez-Castro & Reynoso (2021) report fossil material of a shelduck and a ringed kingfisher from the Chapala-Zacoalco basins (

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

), providing new information on the distribution of these birds in the Late Pleistocene. * An assemblage of bird bones dated to late Pleistocene through middle Holocene is described from the Istykskaya cave (

Pamir Mountains The Pamir Mountains are a Mountain range, range of mountains between Central Asia and South Asia. They are located at a junction with other notable mountains, namely the Tian Shan, Karakoram, Kunlun Mountains, Kunlun, Hindu Kush and the Himalaya ...

;

Tajikistan Tajikistan, officially the Republic of Tajikistan, is a landlocked country in Central Asia. Dushanbe is the capital city, capital and most populous city. Tajikistan borders Afghanistan to the Afghanistan–Tajikistan border, south, Uzbekistan to ...

) by Zelenkov, Sayfulloev, Shnaider (2021), who report the presence of bones of the water rail and a species of ''

Podiceps ''Podiceps'' is a genus of birds in the grebe family. The genus name comes from Latin , "rear-end" and ', "foot", and is a reference to the placement of a grebe's legs towards the rear of its body. It has representatives breeding in all contine ...

'' (the black-necked grebe or the horned grebe) which were not recorded at such high altitudes before, and interpret this finding as evidence of milder environmental conditions in Eastern Pamir during late Quaternary. * A study on the sensory systems in extant kiwis and the

kākāpō The kākāpō (; : ; ''Strigops habroptilus''), sometimes known as the owl parrot or owl-faced parrot, is a species of large, nocturnal, ground-dwelling parrot of the superfamily Strigopoidea. It is endemic to New Zealand. Kākāpō can be u ...

and extinct moa and elephant birds is published by Johnston & Mitchell (2021). * A study aiming to determine the impact of global climatic changes during the last 120,000 years on Afro-Palearctic migrant birds, as indicated by paleoclimate data and genomic-based estimates of effective population size, is published by Thorup ''et al.'' (2021).

Pterosaurs

New pterosaur taxa

Pterosaur research

* A study aiming to determine the nature and average number of osteological characters used to diagnose pterosaur species, as well as aiming to estimate how many pterosaur taxa are still unknown, is published by Fernandes, Nunes & Costa (2021). * A study on the phylogenetic affinities of pterosaurs is published by Baron (2021). * A study on the flight abilities of hatchling pterosaurs is published by Naish, Witton & Martin-Silverstone (2021). * A study on size range of pterosaurs from the Cretaceous Kem Kem Group (Morocco) and on the bone histology of small pterosaur specimens from these strata is published by Smith ''et al.'' (2021), who interpret their findings as indicating that in the Cretaceous period the niches previously occupied by small pterosaurs were increasingly occupied by early

stages of large pterosaurs rather than by birds. * New information on the skeletal anatomy of '' Austriadraco dallavecchiai'' is provided by Dalla Vecchia (2021). * Fossil material of a rhamphorhynchine pterosaur is described from the Upper Jurassic Cerro Campamento Formation (

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

) by Alarcón-Muñoz ''et al.'' (2021), representing the first record of this group from

Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...

reported to date. * An early juvenile or late hatchling specimen of ''

Kunpengopterus ''Kunpengopterus'' is a genus of wukongopterid pterosaur from the middle-late Jurassic Tiaojishan Formation of northeastern China. The genus contains two species, the type species ''K. sinensis'' and ''K. antipollicatus''. History of discovery ...

sinensis'', providing new information on the skeletal changes during

in wukongopterids, is described from the

Tiaojishan Formation The Tiaojishan Formation is a geological formation in Hebei and Liaoning, People's Republic of China, dating to the middle-late Jurassic period (Bathonian-Oxfordian (stage), Oxfordian stages). It is known for its Lagerstätte, exceptionally preser ...

(

) by Jiang ''et al.'' (2021). * Pêgas, Costa & Kellner (2021) attempt to reconstruct the adductor musculature of the pterodactyloid skull, and to estimate bite force for nine pterodactyloid species. * A study on soft tissues of a pterodactyloid specimen from the Upper Jurassic Solnhofen Limestones (

) is published by Pittman ''et al.'' (2021), who interpret their findings as providing evidence of the presence of a biological wing root fairing in pterosaurs. * A well-preserved large skull of '' Ctenochasma elegans'' is described from the Upper Jurassic Painten Formation (

) by Bennett (2021). * Partial mandible of '' Forfexopterus'' is described from the Early Cretaceous Jehol Biota (China) by Zhou, Wang & Wang (2021), who report evidence of tooth wear in this specimen, making it the first known record of tooth-tooth occlusion in ctenochasmatids, and evaluate its implications for the knowledge of the feeding strategy of ctenochasmatids. * Fragment of an

ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...

of a pteranodontid pterosaur is described from the

locality Polunino 2 (

Volgograd Oblast Volgograd Oblast ( rus, Волгоградская область, p=vəɫɡɐˈgratskəjə ˈobɫəsʲtʲ) is a federal subjects of Russia, federal subject (an oblast) of Russia, located in the Volga region, lower Volga region of Southern Russia ...

) by Averianov & Yarkov (2021), representing the first record of the family Pteranodontidae from the Lower Volga region reported so far. * A review of putative boreopterid pterosaurs from the

was published by Yun (2021), who concluded that they could not be confidently referred to Boreopteridae. * New specimen of '' Istiodactylus latidens'', probably coming from the Lower Cretaceous

Vectis Formation The Vectis Formation is a geological Formation (geology), formation on the Isle of Wight and Swanage, England whose strata were formed in the Barremian, approximately 125 million years ago."Magnetostratigraphy of the Lower Cretaceous Vectis Forma ...

(

) and possibly representing the missing jaws of the

of this species, is described by Averianov ''et al.'' (2021). * Bantim ''et al.'' (2021) describe a pteranodontoid pterosaur with anhanguerid affinities from

-age deposits of the Romualdo Formation (

). * A new pterodactyloid mandible from the

of Germany is described by Abel ''et al.'' (2021), representing the oldest anhanguerian known to date. * A study on the variation of pneumaticity patterns in the vertebral column of an anhanguerid specimen from the Romualdo Formation is published by Buchmann ''et al.'' (2021). * Solonin ''et al.'' (2021) describe teeth from the Upper Cretaceous (

) Dmitrov Formation (

Ryazan Oblast Ryazan Oblast (, ) is a federal subjects of Russia, federal subject of Russia (an oblast). Its administrative center is the types of inhabited localities in Russia, city of Ryazan, which is also the oblast's largest city. Geography Ryazan Oblast ...

, Russia), referrable to ornithocheirid pterosaurs, leading to the first occurrence of them in said formation. * A well-preserved, almost complete and articulated new specimen of '' Tupandactylus navigans'', associated with soft tissue remains, is described from the Lower Cretaceous

Crato Formation The Crato Formation is a geologic formation (stratigraphy), formation of Early Cretaceous (Aptian) age in northeastern Brazil's Araripe Basin. It is an important Lagerstätten, Lagerstätte (undisturbed fossil accumulation) for palaeontology, pa ...

(

) by Beccari ''et al.'' (2021). * New specimen of '' Sinopterus dongi'', improving knowledge on the anatomy of this pterosaur, is described from the Lower Cretaceous

(China) by Shen ''et al.'' (2021). * Partial

of a large-sized dsungaripteroid pterosaur is described from the Upper Jurassic (

Kimmeridgian In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 154.8 ±0.8 Ma and 149.2 ±0.7 Ma (million years ago). The Kimmeridgian follows the Oxfordian ...

) Praia da Amoreira–Porto Novo Formation (

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

) by Bertozzo ''et al.'' (2021), representing the second confirmed report of a dsungaripteroid from the Jurassic, and the first record of this group from the Iberian Peninsula reported to date. * Postcranial elements referrable to '' Lonchognathosaurus'', confirming the validity of the genus and providing new information on the anatomy of this pterosaur, are described from the Lower Cretaceous Lianmuqin Formation (China) by Augustin ''et al.'' (2021). * 114 small pterosaur footprints, possibly produced by pterosaurs belonging to the species '' Noripterus complicidens'', are described from the Lower Cretaceous Shengjinkou Formation (China) by Li, Wang & Jiang (2021), who name a new ichnospecies '' Pteraichnus wuerhoensis''. * New fossil material of pterosaurs is described from the Lower Cretaceous Lianmuqin Formation (China) by Augustin ''et al.'' (2021), who interpret these fossils as probable evidence of the presence of a second dsungaripterid taxon (distinct from ''Lonchognathosaurus'') in this formation. * New fossil material of dsungaripterids is described from the Lower Cretaceous Hutubei Formation (China) by Augustin ''et al.'' (2021), representing the first record of pterosaurs from this formation reported to date, and one of the oldest records of dsungaripterids from the Tugulu Group. * A study on the internal architecture and mechanical properties of a hyper-elongate cervical vertebra of an Azhdarchidae, azhdarchid pterosaur from the

(

) is published by Williams ''et al.'' (2021). * Fragment of the wing metacarpal of an azhdarchid is described from the

of the Orenburg Oblast (

) by Averianov, Zverkov & Nikiforov (2021), representing the first record of a pterosaur from the Late Cretaceous of Southern Urals reported to date. * A study on the anatomy and phylogenetic affinities of ''Aerotitan sudamericanus'' is published by Pêgas ''et al.'' (2021; final version published in 2022), who name the new clades Azhdarchomorpha and Alanqidae. * A large wing bone (possibly an

) of a pterosaur with an estimated wingspan comparable with the

specimen of ''Cryodrakon boreas'' is described from the

(

, United States) by Farke (2021). *Studies on the paleoenvironment, functional morphology, and the phylogenetic affinities of ''Quetzalcoatlus,'' which also focuses on the phylogeny of pterosaurs in general and names the new clades Azhdarchiformes, Nyctosauromorpha and Ornithocheiriformes are published by Lehman ''et al.'' (2021), Padian ''et al.'' (2021) and Andres (2021).

Other archosaurs

Other archosaur research

* Marchetti ''et al.'' (2021) revise the tetrapod (including Dinosauromorpha, dinosauromorph) footprint assemblage from the Quarziti del Monte Serra Formation (Ladinian of

), and interpret this assemblage and other findings of Ladinian dinosauromorph footprints as evidence of wide dispersal of dinosauromorphs as early as the Middle Triassic. * The first putative forelimb and pectoral girdle of ''Lagerpeton chanarensis'' is described by McCabe & Sterling Nesbitt, Nesbitt (2021). * A study on the nature of tooth attachment in Silesauridae, silesaurids, and on its implications of the knowledge of the evolution of tooth attachment of archosaurs, is published by Mestriner ''et al.'' (2021). * Two partial skeletons of ''Lewisuchus admixtus'', providing new information on the anatomy of this Dinosauriformes, dinosauriform, are described from the Chañares Formation (Argentina) by Agnolín ''et al.'' (2021).

General research

* A study on the relationship between full potential joint mobility and the poses used during locomotion in extant American alligator and helmeted guineafowl, evaluating its implications for reconstructions of locomotion of extinct archosaurs, is published by Manafzadeh, Kambic, and Gatesy (2021). * A study on the femoral shape variation and on the relationship between femoral morphology and locomotor habits in early archosaurs and non-archosaur Archosauriformes, archosauriforms is published by Pintore ''et al.'' (2021). * A study estimating moment arms for major Pelvis, pelvic limb muscles in extant and fossil archosaurs, aiming to investigate the idea that bird-line archosaurs switched from hip-based to knee-based locomotion between Archosauria (especially Neotheropoda) and Aves, is published by Allen, Kilbourne & Hutchinson (2021). * A study aiming to determine how

changes in skeletal anatomy influence muscle size, leverage, orientation, and locomotor function during the development of flight in extant chukar partridge is published by Heers ''et al.'' (2021), who evaluate the implications of their findings on current knowledge of how extinct winged Theropoda, theropods might have achieved bird-like behaviors before acquiring fully bird-like anatomies. * A study on jumping mechanics and performance in extant elegant crested tinamou, and on its implications for inferences of jumping abilities in extinct animals such as Dromaeosauridae, dromaeosaurid dinosaurs, is published by Bishop ''et al.'' (2021). * A study on the morphological diversity and evolution of the semicircular canals of the inner ear in extant and fossil archosaurs is published by Bronzati ''et al.'' (2021). * A study on the evolution of eggshell thickness in non-avian dinosaurs and birds is published by Legendre & Clarke (2021). * A study on the evolution of birdlike locomotor abilities and hearing acuity, as indicated by the anatomy of the inner ear in extant and fossil reptiles and birds, is published by Hanson ''et al.'' (2021); the conclusions of the study are subsequently contested by David, Bronzati & Benson (2022). * A study assessing the accuracy of bite force estimates in extinct archosaurs and mammals is published by Sakamoto (2021). * A study on the composition of the assemblage of isolated archosaur (dinosaur and crocodyliform) teeth and

s from the Upper Cretaceous Cerro Fortaleza Formation (

), and on its implications for the knowledge of the archosaur biodiversity in southern Patagonia during the Late Cretaceous, is published by Paulina-Carabajal ''et al.'' (2021). * A study on evolution of the expression of carotenoids in skin and other integumentary structures of archosaurs is published by Davis & Clarke (2021). * A study on the ossification patterns of the respiratory turbinate in extant birds, and on their implications for the identification of the positions and form of possible osteological correlates of the respiratory turbinate in non-avian dinosaurs, is published by Tada & Tsuihiji (2021). * Revision of the Mesozoic and Cenozoic record of large, unwebbed bird and bird-like footprints is published by Lockley, Abbassi & Helm (2021).

References

{{reflist Archosaurs 2021 in paleontology