''Bagaceratops'' (meaning "small-horned face") is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of small

protoceratopsid Protoceratopsidae is a family of basal (primitive) ceratopsians from the Late Cretaceous period. Although ceratopsians have been found all over the world, protoceratopsids are only definitively known from Cretaceous strata in Asia, with most spec ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

s that lived in

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

during the

Late 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 ''cre ...

, around 72 to 71 million years ago. ''Bagaceratops'' remains have been reported 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 ...

and

Bayan Mandahu Formation The Bayan Mandahu Formation (also known as Wulansuhai Formation or Wuliangsuhai Formation) is a geological unit of "redbeds" located near the village of Bayan Mandahu in Inner Mongolia, China, in the Gobi Desert. It dates from the late Cretaceous ...

. One specimen may argue the possible presence of ''Bagaceratops'' in the Djadochta Formation. ''Bagaceratops'' was among the smallest ceratopsians, growing up to in length, with a weight about . Although emerging late in the reign of the dinosaurs, ''Bagaceratops'' had a fairly primitive anatomy—when compared to the much derived ceratopsids—and kept the small body size that characterized early ceratopsians. Unlike its close relative, ''

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 ...

'', ''Bagaceratops'' lacked premaxillary teeth (cylindrical, blunt teeth near the tip of the upper jaw).

History of discovery

During the large field work of the Polish-Mongolian Palaeontological Expeditions in the 1970s, abundant protoceratopsid specimens were discovered on eroded surfaces of the Hermiin Tsav locality of the

Gobi Desert The Gobi Desert (, , ; ) is a large, cold desert and grassland region in North China and southern Mongolia. It is the sixth-largest desert in the world. The name of the desert comes from the Mongolian word ''gobi'', used to refer to all of th ...

. This newly collected and rich fossil material is stored in the Institute of Paleobiology of the

Polish Academy of Sciences The Polish Academy of Sciences (, PAN) is a Polish state-sponsored institution of higher learning. Headquartered in Warsaw, it is responsible for spearheading the development of science across the country by a society of distinguished scholars a ...

(

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...

). In 1975, two of the expedition's leading scientists, namely Polish paleontologists

Teresa Maryańska Teresa Maryańska (1937 – 3 October 2019) was a Polish paleontologist who specialized in Mongolian dinosaurs, particularly pachycephalosaurians and ankylosaurians. She is considered not only as one of Poland's but also one of the world's leadin ...

and Halszka Osmólska, published a large

monograph A monograph is generally a long-form work on one (usually scholarly) subject, or one aspect of a subject, typically created by a single author or artist (or, sometimes, by two or more authors). Traditionally it is in written form and published a ...

dedicated to describe this material where they named the new genus and type species of protoceratopsid ''Bagaceratops rozhdestvenskyi''. The selected

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 ...

is ZPAL MgD-I/126, which consists of a relatively medium-sized skull, and a vast majority of the specimens collected by the expeditions were assigned to ''Bagaceratops'', including juvenile and sub-adult skulls. The generic name, ''Bagaceratops'', means "small-horned face" and is derived from the Mongolian ''baga'' = meaning small; and

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

''ceratops'' = meaning horn face. The specific name, ''B. rozhdestvenskyi'', is named in honor of the Russian

paleontologist 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 geolo ...

Anatoly Konstantinovich Rozhdestvensky Anatoly Konstantinovich Rozhdestvensky (, 1920–1983) was a Soviet paleontologist responsible for naming many dinosaurs, including '' Aralosaurus'' and '' Probactrosaurus''. References Soviet paleontologists 1920 births 1983 deaths Russi ...

for his notorious work on dinosaurs.

Additional specimens

In 1993, the Japan-Mongolia Joint Paleontological Expedition collected an articulated and nearly complete ''Bagaceratops'' skeleton (MPC-D 100/535) from the Barun Goyot Formation at the Hermiin Tsav locality. In 2010 and 2011 this specimen was examined to analyze several borings (tunnel-like holes) left by invertebrae scavengers on joint areas. As of 2019, MPC-D 100/535 remains largely undescribed. In 2019 a partial skeleton (specimen KID 196) of ''Bagaceratops'' was described by Bitnara Kim and colleagues, who noted no significant differences between the skeleton of ''Protoceratops'' and the former, with the exception of the anatomy of the skull and the shape and location of the

clavicle The clavicle, collarbone, or keybone is a slender, S-shaped long bone approximately long that serves as a strut between the scapula, shoulder blade and the sternum (breastbone). There are two clavicles, one on each side of the body. The clavic ...

s. This specimen was discovered in 2007 also from the Hermiin Tsav locality of the Barun Goyot Formation, and includes a partially preserved skull with partial skeleton of an adult individual. In 2020, Czepiński described new specimens of ''Bagaceratops'' and ''Protoceratops'' from the Udyn Sayr and Zamyn Khond localities, respectively, of the Djadochta Formation, and evaluated the implications of these specimens for correlation of fossil sites of the latter formation. He considered one of these specimens in particular, MPC-D 100/551B, as a potential evidence of an

anagenetic Anagenesis is the gradual evolution of a species that continues to exist as an interbreeding population. This contrasts with cladogenesis, which occurs when branching or splitting occurs, leading to two or more lineages and resulting in separate ...

transition from ''Protoceratops andrewsi'' to ''Bagaceratops rozhdestvenskyi''.

Synonyms

Juvenile remains, at first tentatively named ''Protoceratops kozlowskii'', and then renamed ''

Breviceratops kozlowskii ''Breviceratops'' (meaning "short horned face") is a genus of protoceratopsid dinosaur that lived during the Late Cretaceous in what is now the Barun Goyot Formation, Mongolia. Discovery and naming The first fossils were discovered during the ...

'' by Kurzanov in 1990, were considered to be juvenile ''Bagaceratops''.

Paul Sereno Paul Callistus Sereno (born October 11, 1957) is a professor of paleontology at the University of Chicago who has discovered several new dinosaur species on several continents, including at sites in Inner Mongolia, Argentina, Morocco and Niger. ...

in 2000 explained this by extrapolating that the juvenile ''Breviceratops'' would grow into a mature ''Bagaceratops''. In 2003 Russian paleontologist Vladimir R. Alifanov named the new taxa ''Lamaceratops tereschenkoi'' and ''Platyceratops tatarinovi'' from the Barun Goyot Formation. Material assigned by Alifanov corresponds to the holotype of ''Lamaceratops'' (PIN 4487/26; a partial small-sized skull), recovered from the Khulsan locality, and the holotype of ''Platyceratops'' (PIN 3142/4; an almost complete medium-sized skull), found in the

red beds Red beds (or redbeds) are sedimentary rocks, typically consisting of sandstone, siltstone, and shale, that are predominantly red in color due to the presence of ferric oxides. Frequently, these red-colored sedimentary strata locally contain t ...

of the Hermiin Tsav locality. He also coined the family Bagaceratopidae in order to contain these new taxa and ''Bagaceratops''. Also during 2003, You Hailu and

Dong Zhiming Dong Zhiming (Chinese language, Chinese: 董枝明, Pinyin: ''Dǒng Zhimíng''; January 1937 – 20 October 2024) was a Chinese vertebrate paleontologist formerly employed at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) ...

described and named the new genus and species of protoceratopsid ''Magnirostris dodsoni'' from red beds at the Bayan Mandahu locality of the

Inner Mongolia Inner Mongolia, officially the Inner Mongolia Autonomous Region, is an Autonomous regions of China, autonomous region of China. Its border includes two-thirds of the length of China's China–Mongolia border, border with the country of Mongolia. ...

(

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 ...

). The holotype of ''Magnirostris'', IVPP V12513, represents a nearly complete skull lacking the frill region of a large individual and was collected during expeditions led by the Sino-Canadian Dinosaur Project. In 2006 Mackoviky regarded all of these ceratopsians as

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. ...

s of ''Bagaceratops'' based on the reasoning that all exhibit anatomical traits already seen on other specimens of this protoceratopsid, and some of them are likely products of preservation. Gobi skelleton

In 2008 Alifanov described and named another ceratopsian taxon from the Barun Goyot Formation, ''Gobiceratops minitus''. Its holotype (PIN 3142/299) is represented by a very small and juvenile skull that was collected from the Hermiin Tsav locality near the end of the 1970s by the Joint Soviet–Mongolian Paleontological Expedition. Though Alifanov used this skull to erect the new ''Gobiceratops'', it had already been displayed for several years at the Moscow Paleontological Museum under the name ''Bagaceratops rozhdestvenskyi''. A comprehensive study on the intraspecific variation in morphology of ''B. rozhdestvenskyi'' was conducted by Polish paleontologist Łukasz Czepiński in

2019 This was the year in which the first known human case of COVID-19 was documented, preceding COVID-19 pandemic, the pandemic which was declared by the World Health Organization the following year. Up to that point, 2019 had been described as ...

, where he concluded that the previously named ''Gobiceratops minutus'', ''Lamaceratops tereschenkoi'', ''Platyceratops tatarinovi'' and ''Magnirostris dodsoni'' represent additional specimens and growth stages of ''B. rozhdestvenskyi'' and therefore, junior synonyms. Czepiński reexamined many of the specimens originally described by Maryańska and Osmólska, as well as the respective holotypes of these taxa, providing evidence that all traits used to separate them are, in fact, indistinguishably present on ''Bagaceratops'' and they fall within the large intraspecific variation of this taxon. He also considered ''Breviceratops'' to be a distinct and separate genus of protoceratopsid, from both ''Bagaceratops'' and ''Protoceratops'', as it features a combination of basal (primitive) and derived (advanced) traits.

Description

''Bagaceratops'' was a small-sized protoceratopsid, reaching adult dimensions of about in length and in body mass based on ''Maginostris''. It had a smaller frill, about ten grinding teeth per jaw, and more triangular skull than its close relative, ''

''. Although both ''Bagaceratops'' and ''Protoceratops'' were very similar (mostly in the postcranial skeleton), the former had a much derived (advanced) skull morphology. ''Bagaceratops'' lacked primitive

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 ...

ry teeth, had paired (fused) nasal bones, and an oval-shaped fenestra (hole) was developed in the

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

—otherwise known as accessory

antorbital fenestra An antorbital fenestra (plural: fenestrae) is an opening in the skull that is in front of the eye sockets. This skull character is largely associated with Archosauriformes, archosauriforms, first appearing during the Triassic Period. Among Extant ...

Classification

''Bagaceratops'' belonged to

Ceratopsia Ceratopsia or Ceratopia ( or ; Ancient Greek, Greek: "horned faces") is a group of herbivore, herbivorous, beaked dinosaurs that thrived in what are now North America, Asia and Europe, during the Cretaceous Period (geology), Period, although ance ...

, a group of herbivorous dinosaurs with

parrot Parrots (Psittaciformes), also known as psittacines (), are birds with a strong curved beak, upright stance, and clawed feet. They are classified in four families that contain roughly 410 species in 101 genus (biology), genera, found mostly in ...

-like beaks which thrived in

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

and

during the Cretaceous Period, which ended roughly 66 million years ago. In 2019 Czepiński analyzed a vast majority of referred specimens to the ceratopsians ''Bagaceratops'' and ''Breviceratops'', and concluded that most were in fact specimens of the former. Although the genera ''Gobiceratops'', ''Lamaceratops'', ''Magnirostris'', and ''Platyceratops'', were long considered valid and distinct taxa, and sometimes placed within

Protoceratopsidae Protoceratopsidae is a family of basal (primitive) ceratopsians from the Late Cretaceous period. Although ceratopsians have been found all over the world, protoceratopsids are only definitively known from Cretaceous strata in Asia, with most spec ...

, Czepiński found the diagnostic features used to distinguish these taxa to be largely present in ''Bagaceratops'' and thus becoming synonyms of this genus. Under this reasoning, Protoceratopsidae consists of ''Bagaceratops'', ''Breviceratops'', and ''Protoceratops''. Based on cranial characters such as presence or absence of premaxillary teeth and an antorbital fenestra, ''P. andrewsi'' is the basal-most protoceratopsid and ''Bagaceratops'' the derived-most one. Below are the proposed phylogenetic relationships within Protoceratopsidae by Czepiński:

Paleoenvironment

Barun Goyot Formation

The

, based on

sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

s, is regarded as

in age (Middle-Upper

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 ...

) and has virtually yielded the bulk of material for which ''Bagaceratops'' is known. This formation is mostly characterized by series of

, mostly light-coloured

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

s (yellowish, grey-brown, and rarely reddish) that are locally cemented. Sandy

claystone Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone and shale. Most of the particles of which the stone is composed are less than and are too small to ...

s (often red-coloured),

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility. Although its permeabil ...

s, conglomerates, and large-scale trough

cross-stratification In geology, cross-bedding, also known as cross-stratification, is layering within a stratum and at an angle to the main bedding plane. The sedimentary structures which result are roughly horizontal units composed of inclined layers. The origina ...

in sands are also common across the unit. In addition, structureless, medium-grained, fine-grained and very fine-grained

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

s predominate in sediments of the Barun Goyot Formation. The sediments of this formation were deposited in

alluvial plain An alluvial plain is a plain (an essentially flat landform) created by the deposition of sediment over a long period by one or more rivers coming from highland regions, from which alluvial soil forms. A ''floodplain'' is part of the process, bei ...

(flat land consisting of sediments deposited by highland

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

s),

lacustrine A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from t ...

, and aeolian paleoenvironments, under relatively

arid Aridity is the condition of geographical regions which make up approximately 43% of total global available land area, characterized by low annual precipitation, increased temperatures, and limited water availability.Perez-Aguilar, L. Y., Plata ...

semiarid climate A semi-arid climate, semi-desert climate, or steppe climate is a dry climate sub-type. It is located on regions that receive precipitation below potential evapotranspiration, but not as low as a desert climate. There are different kinds of se ...

s. ''Bagaceratops'' is the most common taxon across the Barun Goyot Formation, which was also home to many other

vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

s, including the

ankylosaurid 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 ...

s ''

Saichania ''Saichania'' (Mongolian meaning "beautiful one") is a genus of herbivorous ankylosaurid dinosaur from the Late Cretaceous period of Mongolia. The first fossils of ''Saichania'' were found in the early 1970s in Mongolia. In 1977 the type speci ...

'', ''

Tarchia ''Tarchia'' (meaning "brainy one") is a genus of herbivorous ankylosauridae, ankylosaurid dinosaur from the late Cretaceous of Mongolia. Discovery and naming In 1970, a Polish-Mongolian expedition discovered an ankylosaurian skull near Khulsan. ...

'' and '' Zaraapelta'';

alvarezsaurid Alvarezsauridae is a family of small, long-legged dinosaurs. Although originally thought to represent the earliest known flightless birds, they are now thought to be an early diverging branch of maniraptoran theropods. Alvarezsaurids were highly ...

s '' Khulsanurus'' and ''

Parvicursor ''Parvicursor'' (meaning "small runner") is a genus of tiny maniraptoran dinosaur with long slender legs for fast running. Discovery and naming The holotype PIN no. 4487/25, mostly consisting of vertebrae, the pelvis and the right hindlimb, w ...

'';

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

s '' Gobipipus'', '' Gobipteryx'' and '' Hollanda''; fellow

Breviceratops ''Breviceratops'' (meaning "short horned face") is a genus of protoceratopsid dinosaur that lived during the Late Cretaceous in what is now the Barun Goyot Formation, Mongolia. Discovery and naming The first fossils were discovered during the 1 ...

'';

dromaeosaurid Dromaeosauridae () is a family (biology), family of feathered coelurosaurian Theropoda, theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous period (geology), Period. The name Drom ...

s '' Kuru'' and ''

Shri Shri (; , ) is a Sanskrit term denoting resplendence, wealth and prosperity, primarily used as an honorific. The word is widely used in South and Southeast Asian languages such as Assamese, Meitei ( Manipuri), Marathi, Malay (including In ...

''; halszkaraptorine '' Hulsanpes''; pachycephalosaurid '' Tylocephale''; and oviraptorids ''

Conchoraptor ''Conchoraptor'' (meaning "conch plunderer") is a genus of oviraptorid dinosaurs that lived in Asia during the Late Cretaceous epoch, about 70 million years ago. It is known from the Barun Goyot and Nemegt Formation, Nemegt formations of Mongolia ...

'', '' Heyuannia'' and ''

Nemegtomaia ''Nemegtomaia'' is a genus of oviraptorid dinosaur from what is now Mongolia that lived in the Late Cretaceous Period (geology), Period, about 70million years ago. The first specimen was found in 1996, and became the basis of the new genus and s ...

''. Other taxa are represented by the

large Large means of great size. Large may also refer to: Mathematics * Arbitrarily large, a phrase in mathematics * Large cardinal, a property of certain transfinite numbers * Large category, a category with a proper class of objects and morphisms (o ...

titanosaur '' Quaesitosaurus'', and a wide diversity of

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s and

squamate Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest Order (biology), order of reptiles; most members of which are commonly known as Lizard, lizards, with the group also including Snake, snakes. With over 11,991 species, it i ...

Bayan Mandahu Formation

The

, which yielded ''Magnirostris'' (now synonym of ''Bagaceratops''), is considered to be Late Cretaceous in age, roughly

. The dominant

lithology The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lit ...

is reddish-brown, poorly cemented, fine grained sandstone with some conglomerate, and

caliche Caliche () is a soil accumulation of soluble calcium carbonate at depth, where it precipitates and binds other materials—such as gravel, sand, clay, and silt. It occurs worldwide, in aridisol and mollisol soil orders—generally in arid or se ...

. Other facies include

alluvial Alluvium (, ) is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluvium is also sometimes called alluvial deposit. Alluvium is ...

(

stream A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a strea ...

-deposited) and aeolian (

wind Wind is the natural movement of atmosphere of Earth, air or other gases relative to a planetary surface, planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heatin ...

-deposited) sediments. It is likely that sediments at Bayan Mandahu were deposited by short-lived rivers and

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

s on an alluvial plain with a combination of

dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat ...

field paleoenvironments, under a semi-arid climate. The formation is known for its vertebrate fossils in life-like poses, most of which are preserved in unstructured sandstone, indicating a catastrophic rapid burial. This formation has produced numerous

s, such as closely related protoceratopsid ''

''; ankylosaurid ''

Pinacosaurus ''Pinacosaurus'' (meaning "Plank lizard") is a genus of ankylosaurid thyreophoran dinosaur that lived in Asia during the Late Cretaceous (Campanian, roughly 75 to 71 million years ago), mainly in Mongolia and China. The first remains of the genu ...

''; alvarezsaurid ''

Linhenykus ''Linhenykus'' is an extinct genus of alvarezsaurid theropod dinosaur from the Late Cretaceous of Inner Mongolia, China. It is the most basal known member of the Parvicursorinae. The genus gets its name from Linhe, a city near the site where t ...

''; dromaeosaurids ''

Linheraptor ''Linheraptor'' is a genus of dromaeosaurid dinosaur which lived in what is now China in the Late Cretaceous. It was named by Xu Xing (paleontologist), Xu Xing and colleagues in 2010, and contains the species ''Linheraptor exquisitus''. This bird ...

'' and ''

Velociraptor ''Velociraptor'' (; ) is a genus of small dromaeosaurid dinosaurs that lived in Asia during the Late Cretaceous epoch, about 75 million to 71 million years ago. Two species are currently recognized, although others have been assigned in th ...

''; oviraptorids '' Machairasaurus'' and '' Wulatelong''; and

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 ...

s '' Linhevenator'', '' Papiliovenator'', and '' Philovenator''. Other paleofauna from this unit comprises a variety of squamates and mammals, and

nanhsiungchelyid Nanhsiungchelyidae is an extinct family of land turtles known from Cretaceous deposits in Asia and North America. Nanhsiungchelyids were more terrestrial than many of their contemporaries, and may have gone extinct at the K–Pg event, end of the ...

turtle Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Crypt ...

References

External links

HVNHM on ''Bagaceratops''
{{Taxonbar, from=Q131256 Protoceratopsidae Dinosaur genera Campanian dinosaurs Djadochta Formation Fossil taxa described in 1975 Taxa named by Halszka Osmólska Taxa named by Teresa Maryańska Dinosaurs of Mongolia