''Undorosaurus'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

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 ...

ophthalmosaurid Ophthalmosauridae is an extinct family of thunnosaur ichthyosaurs from the Middle Jurassic to the early Late Cretaceous (Bajocian - Cenomanian) worldwide. Almost all ichthyosaurs from the Middle Jurassic onwards belong to the family, until the e ...

ichthyosaur Ichthyosauria is an order of large extinct marine reptiles sometimes referred to as "ichthyosaurs", although the term is also used for wider clades in which the order resides. Ichthyosaurians thrived during much of the Mesozoic era; based on fo ...

known from western

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

Svalbard Svalbard ( , ), previously known as Spitsbergen or Spitzbergen, is a Norway, Norwegian archipelago that lies at the convergence of the Arctic Ocean with the Atlantic Ocean. North of continental Europe, mainland Europe, it lies about midway be ...

, and

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...

. It was a large ichthyosaur, with the type species measuring long.

Discovery and naming

''Undorosaurus'' was named by Vladimir M. Efimov in

1999 1999 was designated as the International Year of Older Persons. Events January * January 1 – The euro currency is established and the European Central Bank assumes its full powers. * January 3 – The Mars Polar Lander is launc ...

and the

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

is ''Undorosaurus gorodischensis''. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

is named after , the type locality of this taxon. ''U. trautscholdi'' is named in honor of the geologist

Hermann Trautschold Gustav Heinrich Ludwig Hermann Trautschold (, tr. ; 17 September 1817 – October 22, 1902) was a German-Russian geologist and paleontologist and also pharmacist. From 1869 to 1888 he was a professor at the Petrovsky Agricultural and Forestry Ac ...

who collected and made the first description of the fossils of the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

of the species. ''Undorosaurus'' was first known from the

UPM EP-II-20 (527), a partial three-dimensionally preserved

skeleton A skeleton is the structural frame that supports the body of most animals. There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal fra ...

which preserved partial

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

. It was collected near the

Volga river The Volga (, ) is the longest river in Europe and the longest endorheic basin river in the world. Situated in Russia, it flows through Central Russia to Southern Russia and into the Caspian Sea. The Volga has a length of , and a catchment ...

at Gorodischi from the ''Epivirgatites nikitini'' ammonoid zone, dating to the

Late Jurassic The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans the geologic time scale, geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic stratum, strata.Owen ...

. A second species, ''U. trautscholdi'', was discovered in 1878 by

and was described by M.S. Arkhangelsky and N.G. Zverkov in

2014 The year 2014 was marked by the surge of the Western African Ebola epidemic, West African Ebola epidemic, which began in 2013, becoming the List of Ebola outbreaks, most widespread outbreak of the Ebola, Ebola virus in human history, resul ...

from a partial left forefin found in the locality of ,

Moscow Oblast Moscow Oblast (, , informally known as , ) is a federal subjects of Russia, federal subject of Russia (an oblast). With a population of 8,524,665 (Russian Census (2021), 2021 Census) living in an area of , it is one of the most densely populate ...

. The holotype (specimen GMUL UŁ no. 3579-81) of the third species, ''U. kielanae'', was discovered in the

Kcynia Formation Kcynia () is a town in Nakło County, Kuyavian-Pomeranian Voivodeship, in north-central Poland, with 4,702 inhabitants (2010). It is located in the Pałuki ethnographic region in the northern part of historic Greater Poland. History Kcynia start ...

of the Owadów-Brzezinki Quarry,

, and it was first described by Daniel Tyborowski in 2016 as ''

Cryopterygius ''Undorosaurus'' is an extinct genus of ophthalmosaurid ichthyosaur known from western Russia, Svalbard, and Poland. It was a large ichthyosaur, with the type species measuring long. Discovery and naming ''Undorosaurus'' was named by Vladimir ...

kielanae''. ''C. kielanae'' was moved to ''Undorosaurus'' by Zverkov & Efimov (2019).

Classification

Maisch and Matzke (2000) regarded ''Undorosaurus'' to be a species of ''

Ophthalmosaurus ''Ophthalmosaurus'' (Greek ὀφθάλμος ''ophthalmos'' 'eye' and σαῦρος ''sauros'' 'lizard') is a genus of ichthyosaur known from the Middle-Late Jurassic. Possible remains from the earliest Cretaceous, around 145 million years ago, a ...

''. However, Storrs ''et al.'' 2000 rejected this synonymy based on the tooth morphology of the specimen. Chris McGowan and Ryosuke Motani (2003) pointed out two noteworthy differences to ''Ophthalmosaurus'', an incompletely fused ischiopubis and a remarkably strong dentition, and considered ''Undorosaurus'' to be a valid genus of ophthalmosaurid.McGowan C, Motani R. 2003. Ichthyopterygia. – In: Sues, H.-D. (ed.): ''Handbook of Paleoherpetology, Part 8, Verlag Dr. Friedrich Pfeil'', 175 pp., 101 figs., 19 plts; München ''Undorosauruss validity is now accepted by most authors, even by Maisch (2010) who originally proposed the synonymy. Zverkov & Efimov (2019) considered the genus ''

'' to 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 the genus ''Undorosaurus''. The authors considered the type species of the former genus, ''C. kristiansenae'', to be synonymous with ''Undorosaurus gorodischensis''; second species of ''Cryopterygius'', ''C. kielanae'', was tentatively maintained by the authors as a distinct species within the genus ''Undorosaurus''.

Phylogeny

The following cladogram shows a possible phylogenetic position of ''Undorosaurus'' in Ophthalmosauridae according to the analysis performed by Zverkov and Jacobs (2020).

Cryopterygius

''Cryopterygius'' (meaning 'frozen fin' in Greek) is a dubious

known from the

Agardhfjellet Formation The Agardhfjellet Formation is a Formation (geology), geologic formation in Svalbard, Norway. It preserves fossils dating back to the Oxfordian (stage), Oxfordian to Berriasian stages, spanning the Late Jurassic-Early Cretaceous boundary. The for ...

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

. One species was recognised: ''C. kristiansenae''.Low resolution pdfHigh resolution pdf
The holotype, PMO 214.578, consists of a single, but largely complete specimen from the Slottsmøya Member of the

that was excavated between 2004 and 2012. Druckenmiller et al. (2012) subsequently named and described ''C. kristiansenae'' on the basis of this specimen. It has been suggested that ''C. kristiansenae'' may also be synonymous with ''Undorosaurus''. A second species, ''C. kielanae'', was found in the

from the Late Jurassic of

. It has since been synonymised with ''Undorosaurus'' and was found to be a species of ''Undorosaurus'' (''U. kielanae'').

References

{{Taxonbar, from=Q7884034, from2=Q5190548 Extinct animals of Russia Late Jurassic ichthyosaurs Fossil taxa described in 1999 Ophthalmosaurinae Ichthyosauromorph genera

Discovery and naming

Classification

Phylogeny

Cryopterygius

See also

References