extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
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 ...
of
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 ex ...
ichthyosaur
Ichthyosaurs (Ancient Greek for "fish lizard" – and ) are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia ('fish flippers' – a designation introduced by Sir Richard Owen in 1842, altho ...
known from western
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 ...
,
Svalbard
Svalbard ( , ), also known as Spitsbergen, or Spitzbergen, is a Norwegian archipelago in the Arctic Ocean. North of mainland Europe, it is about midway between the northern coast of Norway and the North Pole. The islands of the group range ...
, and
Poland
Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populous ...
. It was a large ichthyosaur, with the type species measuring long and weighing .
Discovery and naming
''Undorosaurus'' was named by Vladimir M. Efimov in
1999
File:1999 Events Collage.png, From left, clockwise: The funeral procession of King Hussein of Jordan in Amman; the 1999 İzmit earthquake kills over 17,000 people in Turkey; the Columbine High School massacre, one of the first major school shootin ...
and 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 ''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 Gorodische, the type locality of this taxon. ''U. trautscholdi'' is named in honor of the geologist H. Trautschold who collected and made the first description of the fossils of the holotype of the species.
''Undorosaurus'' was first known from 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 ...
UPM UPM may refer to:
* Ultra-pure metal
* UPM (company), UPM-Kymmene Oyj, a pulp and paper company
* Union pour la méditerrannée, Mediterranean Community
* Union for a Popular Movement, opposition party of France
* Unit production manager, someone ...
EP-II-20 (527), a partial three-dimensionally preserved
skeleton
A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...
which preserved partial
skull
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...
. It was collected near the
Volga river
The Volga (; russian: Во́лга, a=Ru-Волга.ogg, p=ˈvoɫɡə) is the List of rivers of Europe#Rivers of Europe by length, longest river in Europe. Situated in Russia, it flows through Central Russia to Southern Russia and into the Cas ...
at Gorodische from the ''Epivirgatites nikitini'' ammonoid zone, dating to the
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987.
In European lithostratigraphy, the name ...
. A second species, ''U. trautscholdi'' was described by M.S. Arkhangelsky and N.G. Zverkov in
2014
File:2014 Events Collage.png, From top left, clockwise: Stocking up supplies and personal protective equipment (PPE) for the Western African Ebola virus epidemic; Citizens examining the ruins after the Chibok schoolgirls kidnapping; Bundles of wat ...
from a partial left forefin found in the locality of Mnevniki, in the
Moscow Oblast
Moscow Oblast ( rus, Моско́вская о́бласть, r=Moskovskaya oblast', p=mɐˈskofskəjə ˈobləsʲtʲ), or Podmoskovye ( rus, Подмоско́вье, p=pədmɐˈskovʲjə, literally "under Moscow"), is a federal subject of Rus ...
.
Classification
Maisch and Matzke (2000) regarded ''Undorosaurus'' to be a species of ''
Ophthalmosaurus
''Ophthalmosaurus'' (meaning "eye lizard" in Greek) is an ichthyosaur of the Jurassic period (165–150 million years ago). Possible remains from the Cretaceous, around 145 million years ago, are also known. It was a relatively medium-sized ichth ...
''. 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 ''
Cryopterygius
''Cryopterygius'' (meaning 'frozen fin' in Greek) is an extinct genus of ophthalmosaurid ichthyosaur known from the uppermost Jurassic of Central Spitsbergen, Norway. The type species, ''Cryopterygius kristiansenae '', is known from a single, but ...
'' to 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 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).
See also
*
List of ichthyosaurs
This list of ichthyosaurs is a comprehensive listing of all genera that have ever been included in the order Ichthyosauria or the parent clade Ichthyopterygia, excluding purely vernacular terms. The list includes all commonly accepted genera, but a ...
*
Timeline of ichthyosaur research
This timeline of ichthyosaur research is a chronological listing of events in the history of paleontology focused on the ichthyosauromorphs, a group of secondarily aquatic marine reptiles whose later members superficially resembled dolphins, shar ...