''Ondogurvel'' (meaning "egg lizard") 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 ...

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 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 ...

(

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 ...

)

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 ...

in southern

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 ...

. The type and only species is ''O. alifanovi'', known from a partial skeleton consisting of fragments of two last

dorsal vertebrae In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebra (anatomy), vertebrae of intermediate size between the ce ...

, three anterior

sacral vertebrae The sacrum (: sacra or sacrums), in human anatomy, is a triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavity, ...

, right ilium, left and right pubis and

ischium The ischium (; : is ...

, articulated right

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 ...

fibula The fibula (: fibulae or fibulas) or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. ...

metatarsals 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 nu ...

II and IV, and

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. ...

IV-1 and IV-2, right

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 ...

, left and right manual phalanx II-1, right

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 ...

, left pedal phalanx II-1, and fragments of unidentified phalanges.

Discovery and naming

In 2022, the type species ''Ondogurvel alifanovi'' was named and described by Alexander O. Averianov and Alexey V. Lopatin. The generic name, "''Ondogurvel''" combines the Mongolian words "egg" and "lizard". The specific name, "''alifanovi''" honors the late Russian paleontologist Vladimir Alifanov who found the holotype specimen (PIN 5838/1) in 1999.

Description

''Ondogurvel'' was a bipedal

theropod 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 ...

. Like other parvicursorines, it had a robust humerus, and long hindlimbs suggesting a cusorial lifestyle. It is unique in that, unlike all other alvarezsaurids, it has metartarsals II and IV completely fused along their contact area. The following differences from the ''

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 ...

'', another parvicursorine from the Barun Goyot Formation, were identified by Averianov & Lopatin (2022): * dorsally arcuate supraacetabular crest of the ilium; * the tibia less curved labially in transverse plane; * relatively shorter pedal phalanx II-1. On the other hand, describers noted that the femora of ''Ondogurvel'' and ''Parvicursor'' are almost identical. Mickey Mortimer has suggested that ''Ondogurvel'' may be 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 ''Parvicursor,'' which is known only from a juvenile individual.

Classification

Averianov and Lopatin (2022) place ''Ondogurvel'' in the

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

Parvicursorinae which are classified by their manus morphology. They recovered that ''Ondogurvel'' formed a clade with ''

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'' which have proximally co-ossified metatarsals II and IV. The describing paper also proposes that the "drastic difference in the morphology of the carpometacarpus cross Parvicursorinaemay suggest a deep divergence between the parvicursorine lineages represented by 'Dzharaonyx''">Dzharaonyx.html" ;"title="'Dzharaonyx">'Dzharaonyx''– ''Linhenykus'' and ''Mononykus'' – ''Ondogurvel''". Phylogeny after Averianov & Lopatin (2022):

Paleoecology

''Nemegtomaia'', an oviraptorosaur, is also known from the Nemegt locality of the Mongolian

. Other localities from the formation have yielded dinosaurs including other alvarezsaurids (''

Ceratonykus ''Ceratonykus'' (meaning "horned claw") is a monospecific genus of alvarezsaurid dinosaur from Mongolia that lived during the Late Cretaceous (late Campanian stage, 72.1 Ma) in what is now the Barun Goyot Formation. The type and only species, ''C ...

,'' '' Khulsanurus,'' and ''

''), as well as dromaeosaurs ('' Hulsanpes'','''' ''Kuru'', and ''Shri'''), oviraptorosaurs (''

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 ...

'' and '' Heyuannia''), a sauropod ('' Quaesitosaurus''),'''' ceratopsians (''

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 ...

'' and ''

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 ...

''), a pachycephalosaur ('' Tylocephale''), and ankylosaurs (''

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'').

References

{{Taxonbar, from=Q110964964 Alvarezsauridae Dinosaur genera Campanian dinosaurs Baruungoyot Formation Fossil taxa described in 2022 Dinosaurs of Mongolia