''Ceratonykus'' (meaning "horned claw") is a

monospecific In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

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 ...

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 ...

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 ...

from

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 ...

that lived 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 ...

(late

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 ...

stage, 72.1 Ma) in what is now 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 ...

. The type and only species, ''Ceratonykus oculatus'', is known from a fragmentary

skeleton A skeleton is the structural frame that supports the body of most animals. There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal fra ...

, including an incomplete

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

, of an adult individual. It was named and described in

2009 2009 was designated as the International Year of Astronomy by the United Nations to coincide with the 400th anniversary of Galileo Galilei's first known astronomical studies with a telescope and the publication of Astronomia Nova by Joha ...

by Vladimir Alifanov and Rinchen Barsbold. Its describers questioned the traditional placement of alvarezsaurs in

Theropoda Theropoda (; from ancient Greek iktionary:θηρίον, , (''therion'') "wild beast"; wiktionary:πούς, , wiktionary:ποδός, (''pous, podos'') "foot" is one of the three major groups (Clade, clades) of Dinosaur, dinosaurs, alon ...

, instead suggesting they were ornithischians, but this has not been accepted since. ''Ceratonykus'' has an estimated length of and weight of . It has been considered as a possible

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 '' Parvicursor''.

Discovery and naming

Cretaceous-aged dinosaur fossil localities of Mongolia

In 2003, a partial

of an

was discovered in the

of the Khermiin Tsav locality,

by the Paleontological Center of the Mongolian Academy of Sciences (MPC) preparator Otkhoon Zhargal. The skeleton was enclosed in two pieces of rock during the time of the discovery. The specimen was subsequently named and described in

by Vladimir Alifanov and Rinchen Barsbold. 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, MPC no. 100/124, consists of an incomplete

and

lower jaw In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

, cervical

vertebra Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...

e, caudal vertebrae,

sternum The sternum (: sternums or sterna) or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major bl ...

, left and right

coracoid A coracoid is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is present as part of the scapula, but this is n ...

s, a right humeral fragment, distal elements of forelimbs, fragmentary ilium, and hindlimbs. The specimen is of an adult individual based on the fusion of the astragali and

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 ...

e, with partially obliterated sutures. The generic name, ''Ceratonykus'', is derived from the

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 ...

words "''ceratinus''" (horned) and "''onyx''" (claw). The

specific Specific may refer to: * Specificity (disambiguation) * Specific, a cure or therapy for a specific illness Law * Specific deterrence, focussed on an individual * Specific finding, intermediate verdict used by a jury in determining the final ...

name, ''oculatus'', is derived from the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word "''oculatus''" (sharp-sighted, big-eyed).

Description

Size and distinguishing traits

In 2016,

Gregory S. Paul Gregory Scott Paul (born December 24, 1954) is an American freelance researcher, author and illustrator who works in paleontology. He is best known for his work and research on theropoda, theropod dinosaurs and his detailed illustrations, both l ...

gave ''Ceratonykus'' an estimated length of and weight of .Paul, G.S., 2016, ''The Princeton Field Guide to Dinosaurs 2nd Edition'', Princeton University Press However, Molina-Pérez and Larramendi (2016) gave ''Ceratonykus'' an estimated length of and weight of . Alifanov & Barsbold (2009) originally diagnosed ''Ceratonykus'' based on the long preorbital

region; an upper temporal fenestrae ovate that was 0.4 as long as the frontals; the length of the frontal being almost four times greater than its width; the frontals narrowing towards the rostrum into a narrow wedge; the prefrontals adjoining each other towards the middle; the basipterygoid processes being two-thirds as high as the quadrates; the dentaries form a deep and rostrally tapering depression; extensive

mandibular fenestrae The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

; narrow

centra Centra is a convenience shop chain that operates throughout Ireland. The chain operates as a symbol group owned by Musgrave Group, the food wholesaler, meaning the individual shops are all owned by individual franchisees. The chain has three ...

of cervical and anterior

caudal vertebrae Caudal vertebrae are the vertebrae of the tail in many vertebrates. In birds, the last few caudal vertebrae fuse into the pygostyle, and in apes, including humans, the caudal vertebrae are fused into the coccyx. In many reptiles, some of the caud ...

; the deltopectoral crest being separated from the humeral head by a notch; the basal

phalanx The phalanx (: phalanxes or phalanges) was a rectangular mass military formation, usually composed entirely of heavy infantry armed with spears, pikes, sarissas, or similar polearms tightly packed together. The term is particularly used t ...

of the major digit of the manus is extended, with its flanks moderately wide, and a narrow and symmetrical distal condyle; the postacetabular plate of the ilia possessing a relatively small longitudinal craniomedial crest; a strongly curved femora that is nearly half as long as

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 ...

; a distinct fourth trochanter; an undeveloped cnemial crest of the

e; an ascending process of the astragali that is high and wide; the tarsometatarsals being 1.33 as long as the femora; the second and fourth metatarsals tightly adjoining each other over its entire extent; a deep notch that is formed proximodorsally between the metatarsals; the second metatarsals being shorter than the fourth distally; tarsometatarsals that are 3.5 times as long as the third metatarsals; and the basal phalanx of the fourth digit of the hind feet only being slightly shorter than the basal phalanx of second digit.

Cranium

The part of the skull nearest to the

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit ** podium * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ...

is narrow and extended, with a deep occipital region and large

orbits In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an physical body, object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an satellite, artificia ...

. The

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 ...

e were at least half as large as the orbits and the temporal bars are relatively small, while the lower temporal fenestrae are narrow and slightly lower in height than the diameter of the orbits. Both of the frontals are paired, however, the left frontal is missing the posteromedial margin while the right frontal is only known from the rostral end. Both frontals are four times as long as wide, similar to ''Shuvuuia'', and are narrow wedge-shaped in front view. The

squamosal bone The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral ...

s adjoin the

postorbital The ''postorbital'' is one of the bones in vertebrate skulls which forms a portion of the dermal skull roof and, sometimes, a ring about the orbit. Generally, it is located behind the postfrontal and posteriorly to the orbital fenestra. In some ve ...

and the paroccipital process, while also being relatively short and t-shaped. The postorbital bones have a large medial process and connect to the parietal and frontal by a different process. The ventral process of the lacrimals are narrow with the dorsal process being very long and rod-like. Both the jugals and the quadratojugals circular in cross section and are fused but do not form a suture. The quadrates are high, with the distal condyle being present on the occipital crest and the lateral crest being connected to the upper side of the contact zone of the squamosal and postorbital bones. As in ''Shuvuuia'', a notch is present in between the lateral and occipital condyles. The paroccipital processes of the braincase are compressed towards the upper side and underside. The interior of the prootics have a coarse-cellular structure, which can only be viewed on the right side of the skull. The basioccipital forms an occipital condyle on a long and wide neck, while exoccipitals do no not form a part of the condyle. Unlike ''Shuvuuia'', the basipterygoid processes diverge at almost 60° and are almost two-thirds as long as the quadrates. The dentaries are long, with the rostral end slightly expanding vertically and curving downwards. The

have a wide oval shape and an anterior border that is in line with the border between the first and second thirds of the orbits. The lower jaw rami form the para-articular processes, which are in line with the quadrate–mandibular articulation. The base of the right occipital process contained a cavity. A coarse-cellular structure is seen on the right side of the skull. The body of the basioccipital forms an occipital condyle, while the exoccipitals do not form a part of the condyle. The sphenoccipital tubercles are separated by a wide groove and a depression is present in the contact area of the basioccipital and basisphenoid. The basisphenoid coincides with the basipterygoid processes, which slightly compresses towards the sides and middle. The cerebral hemispheres constitute a majority of the brain. These cerebral hemi-spheres are separated from the midbrain by the presence of a sulcus and preserve traces of the brain membrane. An interhemispheric sulcus is present at the start of the

olfactory tract The olfactory tract (olfactory peduncle or olfactory stalk) is a bilateral bundle of afferent nerve fibers from the mitral and tufted cells of the olfactory bulb that connects to several target regions in the brain, including the piriform cort ...

s. The optic lobes are displaced towards the anterior, which is a characteristic of extant birds. The

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

balls would have been positioned towards the brain and are a quarter of the head length in diameter, a feature that suggests the eyesight of alvarezsaurs were the key afferent system. The acoustic tubercles are unusually wide and are positioned between the occipital edge of the cerebral hemispheres and

cerebellum The cerebellum (: cerebella or cerebellums; Latin for 'little brain') is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as it or eve ...

Postcrania

The

atlas An atlas is a collection of maps; it is typically a bundle of world map, maps of Earth or of a continent or region of Earth. Advances in astronomy have also resulted in atlases of the celestial sphere or of other planets. Atlases have traditio ...

is likely represented by the intercentrum, which is low and elongated with the posterior region being broken off. There is a vertically positioned bone that is present on the fragment that likely represents the

neural arch Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...

of the atlas. The series of three cervical vertebrae lack pleurocoels and has condyles that are very small and hemi-spherical. These condyles are also small in other vertebrae. The vertebral centra expand slightly more wider than those of '' Mononykus'' and are slightly more narrower than those of ''

Shuvuuia ''Shuvuuia'' is a genus of bird-like theropod dinosaur from the late Cretaceous period of Mongolia. It is a member of the family Alvarezsauridae, small coelurosaurian dinosaurs which are characterized by short but powerful forelimbs specialized ...

''. The diapophyses on the first two vertebrae of the series are relatively small but are wider at the base and extend towards the sides and underside. The parapophyses are separated by a ventral groove from each other and connect to the diapophyses by a narrow crest on the middle vertebra. The

of this vertebra is wide and low, with the neural spine being completely absent. The first free caudal vertebra has a centrum that is narrow and is moderately high, with a small ventral keel being present near the condyle. Much like the first free caudal vertebra, the three articulated anterior caudal vertebrae have a centrum that is narrow but are high over the entire extent. Different to the first free caudal vertebra and the three articulated anterior caudal vertebrae are two isolated vertebrae of the middle caudal region that have a low centrum, and a barely viewable crest in place of the neural spine. However, all caudal vertebrae are procoelous. The

of the

pectoral 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 ...

is an unpaired bone that lacks a pronounced medial keel. The side surface of the

s is convex, with the posterodorsal edge being thickened and a short crest forming close to the posterosuperior margin. The base of the humeral head was inclined caudally. The deltopectoral crest was separated from the humeral head by a notch, with the upper region resembling a high process based on the rounded outline of the base and foramen in the centre. ''Ceratonykus'' has a basal

of the major digit that is similar to that of ''Mononykus'', but differs in the narrower distal part. The second

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 ...

possesses two spike like bones that range in size which may have been terminal phalanges of digits rather. The posterior plate of the left ilium is wide and flat, with the side margin being arched and the craniomedial part having a longitudinal crest. The femora lack

epiphyses An epiphysis (; : epiphyses) is one of the rounded ends or tips of a long bone that ossify from one or more secondary centers of ossification. Between the epiphysis and diaphysis (the long midsection of the long bone) lies the metaphysis, inc ...

and are convex in the proximal part, while the medial surface is straight. The

e also lacks epiphyses and the tibiotarsals are slightly curved towards the sides in the upper half. The tibiae are subcircular in cross section and lack a projecting part of the external cnemial crest, with the astragali being completely fused to the bones. The metatarsals are one and a third times as long as the femora, with the tarsometatarsus being three and a half times as long as the third metatarsals. Dorsal and palmar grooves are present in the area of connection of the metatarsals and tarsometatarsus, but disappear in the lower palmar third of the tarsometatarsals. As in '' Parvicursor'', the second metatarsals were shorter than the fourth metatarsals, with the metatarsals being widened in the middle part in side view. Due to the poor preservation of the holotype specimen, the shape of articular facets of the metatarsals and digits is not known. Found in natural articulation were the basal phalanges of the second and third digits of the right foot. ''Ceratonykus'' has a similar ratio of the lengths of basal phalanges as ''Mononykus'' as the larger basal phalanx of the fourth digit is slightly shorter than the basal phalanx of the second digit, and the basal phalanx of the third digit is slightly longer than the basal phalanx of the second digit.

Classification

Alifanov & Barsbold (2009) originally placed ''Ceratonykus'' within Alvarezsauria, within the clade Parvicursoridae, as sister taxon to '' Mononykus''. The authors questioned the traditional placement of Alvarezsauria within

, instead suggesting they were ornithischians, but since then this has not been accepted. Qin ''et al.'' (2019) recovered ''Ceratonykus'' within a

polytomy An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tree ...

with '' Linhenykus,'' ''

'', ''Mononykus'' and ''Parvicursor'', a position also recovered by Xu ''et al.'' (2018). Lee ''et al.'' (2019) recovered it in a similar position, but with the inclusion of '' Nemegtonykus'' and a clade containing '' Kol'', ''

Xixianykus ''Xixianykus'' is a genus of alvarezsaurid theropod dinosaur from the late Cretaceous period of China. Known from a slab of rock which contains a partial postcranial skeleton unearthed in the Late Cretaceous ( Coniacian-Santonian) Majiacun For ...

'' and '' Albinykus''. In addition, it was also recovered within a polytomy by Fowler ''et al.'' (2020), with the inclusion of '' Trierarchuncus'', and Averianov & Lopatin (2021), with the inclusion of '' Khulsanurus'', in a strict consensus tree using unweighted characters. However, a strict consensus tree with implied weighting by Averianov & Lopatin (2021) placed it as sister taxon to ''Parvicursor''. Agnolin ''et al.'' (2012) positioned ''Ceratonykus'' within the tribe Ceratonykini, as sister taxon to ''Xixianykus'' and ''Albinykus''. Averianov & Lopatin (2022b) considered ''Ceratonykus'' to be a

of ''Parvicursor'' as the differences between both taxa were minimal and concerned characters that are likely to be

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 ...

and possibly also individual variation. A phylogenetic analysis conducted by Averianov & Lopatin (2022b) is reproduced below. The results of an earlier analysis by Agnolin ''et al.'' (2012) are reproduced below.

Paleobiology

In 2011, Vladimir Alifanov and Sergey Savelyev described the natural

braincase In human anatomy, the neurocranium, also known as the braincase, brainpan, brain-pan, or brainbox, is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the calv ...

cast of ''Ceratonykus''. The authors noted that the brain anatomy is a linear structure, with no bends in the parasagittal plane at the boundaries between the

mesencephalon The midbrain or mesencephalon is the uppermost portion of the brainstem connecting the diencephalon and cerebrum with the pons. It consists of the cerebral peduncles, tegmentum, and tectum. It is functionally associated with vision, hearing, mo ...

and

myelencephalon The myelencephalon or afterbrain is the most posterior region of the embryonic hindbrain, from which the medulla oblongata develops. Myelencephalon is from myel- (bone marrow or spinal cord) and encephalon (the vertebrate brain). Development ...

, a feature that is not seen in

crocodiles Crocodiles (family Crocodylidae) or true crocodiles are large, semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term "crocodile" is sometimes used more loosely to include all extant member ...

birds 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 ...

and other

dinosaurs 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 ...

. The visual and auditory analysers are represented by separate lobes in the midbrain, with the optic lobes being displaced ventrolaterally like that of birds. Alifanov and Savelyev tested the hypothesis of climbing ancestors of alvarezsaurs by looking at the

of ''Ceratonykus'', which has at least one transverse sulcus as in crocodiles but not

lizards Lizard is the common name used for all squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The ...

. Due to crocodiles having a better coordination of movements than lizards, as they need to orient themselves in three dimensional space, the authors proposed that the ancestor of alvarezsaurs were likely

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...

. The authors also suggested that the complex cerebellum could have been useful for efficient regulation of the speed and numerous movement patterns such as jumping in terrestrial alvarezsaurs. Additionally, they considered that specialization of the eyesight, hearing and sense of smell might have made alvarezsaurs efficient for searching for food and hunting. Agnolín ''et al.'' (2021) also noted that the enlarged

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...

of the neck and the expansion of the cerebellum of ''Ceratonykus'' suggests a locomotor improvement in alvarezsaurs.

Paleoenvironment

''Ceratonykus'' is known from the Barun Goyot Formation, which has been dated to the

stage of the

period. The Barun Goyot Formation has a thickness of and overlies the

Djadokhta Formation The Djadochta formation (sometimes transcribed and also known as Djadokhta, Djadokata, or Dzhadokhtskaya) is a highly fossiliferous geological formation in Central Asia, Gobi Desert, dating from the Late Cretaceous period, about 75 million ...

. The

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 of the formation were deposited in various conditions, with the lower part consisting of alternating

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 ...

deposits 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 that existed in interdune areas, while the upper part consisted of sediments that were deposited over an area similar to takyrs that was flooded at irregular intervals. Overall, the formation had a

semi-arid 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 ...

with significant

rain Rain is a form of precipitation where water drop (liquid), droplets that have condensation, condensed from Water vapor#In Earth's atmosphere, atmospheric water vapor fall under gravity. Rain is a major component of the water cycle and is res ...

fall. The fauna of the Barun Goyot Formation consists of the alvarezsaurids '' Khulsanurus'', '' Ondogurvel'' and ''Parvicursor'', the ankylosaurine ankylosaurids ''

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. ...

'', '' Zaraapelta'' and an indeterminate ankylosaurid; the

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 ...

ns ''

Bagaceratops ''Bagaceratops'' (meaning "small-horned face") is a genus of small protoceratopsid dinosaurs that lived in Asia during the Late Cretaceous, around 72 to 71 million years ago. ''Bagaceratops'' remains have been reported from the Barun Goyot Forma ...

'', ''

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 ...

'' and possibly '' Udanoceratops;'' the velociraptorine dromaeosaurids '' 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 ...

;'' the halszkaraptorine unenlagiid '' Hulsanpes;'' the pachycephalosaurid '' Tylocephale;'' the

oviraptorids Oviraptoridae is a group of bird-like, herbivorous and omnivorous maniraptoran dinosaurs. Oviraptorids are characterized by their toothless, parrot-like beaks and, in some cases, elaborate crests. They were generally small, measuring between one ...

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 ...

'', the

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 Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...

'' Quaesitosaurus;'' the enantiornithines '' Gobipteryx'' and '' Gobipipus;'' Kurochkin, E. N.; Chatterjee, S.; Mikhailov, K. E. (2013). An embryonic enantiornithine bird and associated eggs from the cretaceous of Mongolia. Paleontol. J. 47, 1252–1269. and the ornithuromorph

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 ...

'' Hollanda.Bell, A.K., Chiappe, L.M., Erickson, G.M., Suzuki, S., Watabe, M., Barsbold, R. and Tsogtbaatar, K. (2010). "Description and ecologic analysis of ''Hollanda luceria'', a Late Cretaceous bird from the Gobi Desert (Mongolia)." ''Cretaceous Research'', 31(1): 16-26.

References

{{Taxonbar, from=Q675014 Alvarezsauridae Dinosaur genera Maastrichtian dinosaurs Baruungoyot Formation Taxa named by Alexander O. Averianov Taxa named by Rinchen Barsbold Fossil taxa described in 2009 Dinosaurs of Mongolia