''Ondogurvel'' () (meaning "egg lizard") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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 period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger 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 ''creta'', 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. Campanian s ...

)

Barun Goyot Formation The Barun Goyot Formation (also known as Baruungoyot Formation or West Goyot Formation) 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 Pro ...

in southern

Mongolia Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...

. 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 vertebrae and they are intermediate in size between the cervical ...

, three anterior

sacral vertebrae The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, 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 ...

, right ilium, left and right pubis and

ischium The ischium () form ...

, articulated right

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

fibula The fibula 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. Its upper extremity is ...

metatarsals The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the medi ...

II and IV, and

phalanges The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. ...

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 flatt ...

, left and right manual phalanx II-1, right

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...

, 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 өндөг “ondo” (), meaning egg, and гүрвэл “gurvel” (), meaning 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 (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

. 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. At only about from snout to end of tail, and in weight, it was initially seen as one of the smallest non-avian dinosaur ...

'', 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 The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. * In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linna ...

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 subfamily botanical names with "-oideae", and zoologi ...

Parvicursorinae 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 ...

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.Xu, X., Wang, D.Y., Sullivan, C., Hone, D.W.E., Han, F.L., Yan, R.H. and Du, F.M. (2010). "A basal parvicursorine (Theropoda: Alvarezsauridae) ...

'' and ''

Albinykus ''Albinykus'' (meaning " Albin claw", after a term used by Mongolian shamans to describe light phenomena in the Gobi Desert) is a genus of alvarezsaurid dinosaur. Fossils have been found from Late Cretaceous-age (Santonian) Javkhlant Formation in ...

'' 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''.html" ;"title="Dzharaonyx.html" ;"title="'Dzharaonyx">'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 ''Khulsanurus'' (meaning "tail from Khulsan") is an extinct genus of alvarezsaurid theropod dinosaur from the Late Cretaceous Barungoyot Formation of the Khulsan Locality in the Gobi Desert region of Mongolia. The type and only species is ''Khu ...

,'' and ''

''), as well as dromaeosaurs (''

Hulsanpes ''Hulsanpes'' ( meaning " Khulsan foot") is a genus of halszkaraptorine theropod dinosaurs that lived during the Late Cretaceous in what is now the Barun Goyot Formation of Mongolia, about 75-72 million years ago. The remains were found in 1970 ...

'','''' ''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 formations of Mongolia. Discovery When ...

'' and ''

Heyuannia ''Heyuannia'' ("from Heyuan") is a genus of oviraptorid dinosaur that lived in Asia during the Late Cretaceous epoch, in what is now China and Mongolia. It was the first oviraptorid found in China; most others were found in neighbouring Mongolia ...

''), 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 ...

''), a pachycephalosaur (''

Tylocephale ''Tylocephale'' (meaning "swollen head", from the Greek ''τυλη'' meaning 'callus' or 'hard swelling' and ''κεφαλη'' meaning 'head') is a genus of pachycephalosaurid dinosaur from the Late Cretaceous period. It was a herbivorous dinosau ...

''), and ankylosaurs (''

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

'', ''

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 ''Zaraapelta'' is an extinct genus of herbivorous ankylosaurid thyreophoran dinosaur from the Late Cretaceous of Mongolia. The type species is ''Zaraapelta nomadis'', named and described by Arbour ''et al'' in 2014. ''Zaraapelta'' is known from ...

'').

References

{{Portalbar, Paleontology, Cretaceous Alvarezsaurids Fossil taxa described in 2022 Fossils of Mongolia