''Kileskus'' (meaning ''lizard'' in the

Khakas The Khakas (also spelled Khakass; Khakas: , ''khakas'', , ''tadar'', , ''khakastar'', , ''tadarlar'') are a Turkic indigenous people of Siberia, who live in the republic of Khakassia, Russia. They speak the Khakas language. The Khakhassian ...

language) 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 ...

tyrannosauroid Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent b ...

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 ...

known from partial remains found in

Middle Jurassic The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...

(

Bathonian In the geologic timescale the Bathonian is an age and stage of the Middle Jurassic. It lasted from approximately 168.3 Ma to around 166.1 Ma (million years ago). The Bathonian Age succeeds the Bajocian Age and precedes the Callovian Age. Strat ...

stage)

Itat Formation The Itat Formation (Russian: итатская свита) is a geologic formation in western Siberia. It was deposited in the Bajocian to Bathonian ages of the Middle Jurassic. Dinosaur remains are among the fossils that have been recovered from t ...

Sharypovsky District Sharypovsky District (russian: Шары́повский райо́н) is an administrativeLaw #10-4765 and municipalLaw #14-3185 district (raion), one of the forty-three districts in Krasnoyarsk Krai, Russia. It is located in the southwest of the ...

Krasnoyarsk Krai Krasnoyarsk Krai ( rus, Красноя́рский край, r=Krasnoyarskiy kray, p=krəsnɐˈjarskʲɪj ˈkraj) is a federal subject of Russia (a krai), with its administrative center in the city of Krasnoyarsk, the third-largest city in Siber ...

(

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

). Fossils recovered include the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates 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 t ...

, a

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 mammal has b ...

, a

surangular The suprangular or surangular is a jaw bone found in most land vertebrates, except mammals. Usually in the back of the jaw, on the upper edge, it is connected to all other jaw bones: dentary, angular, splenial and articular The articular bone i ...

, and a few bones from the hand and foot. Additional remains referred to the species include cervical and caudal vertebrae, as well as a fibula. The skull bones are similar to those of ''

Proceratosaurus ''Proceratosaurus'' is a genus of carnivore, carnivorous theropod dinosaur from the Middle Jurassic (Bathonian) of England. ''Proceratosaurus'' was a small dinosaur, measuring in length and in body mass.Holtz, Thomas R. Jr. (2008) ''Dinosaurs: ...

''. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''K. aristotocus''. ''Kileskus'' was named in 2010 by Averianov and colleagues. Its size has been estimated at 5.2 meters (17 ft) in length and 700 kg (1,540 lbs) in weight.

Classification

''Kileskus'' has been included in two

phylogenetic analyses In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

and found to be a basal proceratosaurid both times. Although it is unknown whether ''Kileskus'' sported a nasal crest, it can be assigned to Proceratosauridae due to a number of other features. These include elongated external nares, a short ventral margin of the premaxilla, and the area of the antorbital fossa directly below the antorbital fenestra being deeper than the maxilla directly below it. ''Kileskus'' also shares with ''

'' nares inclined posterodorsally at a 40 degree angle to the skull''. Kileskus'' is distinguished from other proceratosaurids by the anterior rim of its maxilla being confluent with the ascending process of the maxilla and gently sloping posterodorsally''.'' Below is a cladogram published in 2013 by Loewen ''et al.''. Cladogram published in 2018.Delcourt, R.; Grillo, O. N. (2018). "Tyrannosauroids from the Southern Hemisphere: Implications for biogeography, evolution, and taxonomy". Palaeogeography, Palaeoclimatology, Palaeoecology. 511: 379–387

References

Proceratosaurids Bathonian life Middle Jurassic dinosaurs of Asia Jurassic Russia Fossils of Russia Fossil taxa described in 2010 {{theropod-stub

Classification

See also

References