''Itilochelys'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

sea turtle Sea turtles (superfamily Chelonioidea), sometimes called marine turtles, are reptiles of the order Testudines and of the suborder Cryptodira. The seven existing species of sea turtles are the flatback, green, hawksbill, leatherback, loggerhe ...

in the family Cheloniidae containing the single species ''Itilochelys rasstrigin''. The species is known only from the Early Paleocene, Danian stage Rasstrigin 2 locality, Dubovsky District,

Volgograd Oblast Volgograd Oblast (russian: Волгогра́дская о́бласть, ''Volgogradskaya oblast'') is a federal subject (an oblast) of Russia, located in the Volga region of Southern Russia. Its administrative center is Volgograd. The populat ...

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History and classification

''Itilochelys rasstrigin'' is known only from three fossils, 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 sever ...

, specimen number "ZIN PH 1/118" and two referred specimens, numbers "ZIN PH 2/118" and "ZIN PH 3/118" . The type specimen is composed of a grouping of cervical vertebrae I-III, partial skull, and disarticulated lower jaw. Specimen ZIN PH 2/118 is an isolated section of

dentary In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

while ZIN PH 3/118 is a right humerus. The fossils were all recovered by A. A. Yarkov from fossiliferous outcrops of the Beryozovaya beds exposed at the Rasstrigin 2 locality. As of 2011, the type and referred specimens are preserved in the Paleoherptological collections housed at the Zoological Institute of the Russian Academy of Sciences, in

Saint Petersburg Saint Petersburg ( rus, links=no, Санкт-Петербург, a=Ru-Sankt Peterburg Leningrad Petrograd Piter.ogg, r=Sankt-Peterburg, p=ˈsankt pʲɪtʲɪrˈburk), formerly known as Petrograd (1914–1924) and later Leningrad (1924–1991), i ...

, Russia. ''Itilochelys'' was first studied by I. G. Danilov and A. O. Averianov of the Zoological Institute along with A. A. Yarkov of the Natural History, Humanitarian Institute in Volgograd. Their 2010 type description of the genus and species was published in the journal ''Proceedings of the Zoological Institute RSA''. The generic name was coined by Danilov, Averianov, and Yarkov as a combination of the medieval Arabian/Persian name of the

Volga River The Volga (; russian: Во́лга, a=Ru-Волга.ogg, p=ˈvoɫɡə) is the longest river in Europe. Situated in Russia, it flows through Central Russia to Southern Russia and into the Caspian Sea. The Volga has a length of , and a catchme ...

, ''Itil'', along with the

Greek Greek may refer to: Greece 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 ...

"chelys", meaning turtle. The specific epithet ''rasstrigin'' is in reference to the type locality of the specimen. ''Itilochelys rasstrigin'' is one of three fossil cheloniid sea turtle taxa which have been recovered from the Volgograd region and the most complete specimen recovered so far. The other two taxa are represented by a specimen of the genus '' Euclastes'' known from the Karpovka site and a specimen related to the genus '' Tasbacka'' from the Malaya Ivanovka site. The placement of ''Itilochelys rasstrigin'' in the family Cheloniidae is supported by the contact of the squamosal and parietal bones, an emarginated v-shaped crest on the underside of the basisphenoid, and features of the nasal bone structure. Placement of the species as a stem member in the family is based on the structure of the humerus which shows a morphology transitioning towards the derived pelagic structuring of modern cheloniids.

References

{{Taxonbar, from=Q6094719 Cheloniidae Prehistoric life of Europe Paleocene turtles Fossil taxa described in 2010 Prehistoric turtle genera Monotypic prehistoric reptile genera Extinct turtles