Itilochelys
Encyclopedia
Itilochelys is an extinct genus
of sea turtle
in the family Cheloniidae
containing the single
species Itilochelys rasstrigin. The species is known only from the Early Paleocene, Danian stage
Rasstrigin 2 locality, Dubovka District
, Volgograd, Russia.
, 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
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
, 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
, Itil, along with the Greek
"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.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of sea turtle
Sea turtle
Sea turtles are marine reptiles that inhabit all of the world's oceans except the Arctic.-Distribution:...
in the family Cheloniidae
Cheloniidae
Cheloniidae is a family of turtles belonging to the sea turtle superfamily Chelonioidea.-Extant genera:*Genus Caretta**Loggerhead sea turtle *Genus Chelonia**Green sea turtle *Genus Eretmochelys...
containing the single
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
species Itilochelys rasstrigin. The species is known only from the Early Paleocene, Danian stage
Danian
The Danian is the oldest age or lowermost stage of the Paleocene epoch or series, the Paleogene period or system and the Cenozoic era or erathem. The beginning of the Danian age is at the Cretaceous-Tertiary extinction event...
Rasstrigin 2 locality, Dubovka District
Dubovka, Volgograd Oblast
Dubovka is a town and the administrative center of Dubovsky District of Volgograd Oblast, Russia, located on the right bank of the Volga River northeast of Volgograd. Population:...
, Volgograd, Russia.
History and classification
Itilochelys rasstrigin is known only from three fossils, the holotypeHolotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
, 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
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
while ZIN PH 3/118 is a right humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
. 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
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
collections housed at the Zoological Institute of the Russian Academy of Sciences
Russian Academy of Sciences
The Russian Academy of Sciences consists of the national academy of Russia and a network of scientific research institutes from across the Russian Federation as well as auxiliary scientific and social units like libraries, publishers and hospitals....
, in Saint Petersburg
Saint Petersburg
Saint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea...
, 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
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
name was coined by Danilov, Averianov, and Yarkov as a combination of the medieval Arabian/Persian name of the Volga River
Volga River
The Volga is the largest river in Europe in terms of length, discharge, and watershed. It flows through central Russia, and is widely viewed as the national river of Russia. Out of the twenty largest cities of Russia, eleven, including the capital Moscow, are situated in the Volga's drainage...
, Itil, along with the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
"chelys", meaning turtle. The specific epithet
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
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
Euclastes
Euclastes is an extinct genus of sea turtle. It was first named by Edward Drinker Cope in 1867, and contains three species. One species, E. hutchisoni, was named in 2003 but has since been reassigned to the genus Pacifichelys.-Description:...
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.
External links
- Itilochelys at the Fossil Wiki.