| Simbirskiasaurus Temporal range: Early Cretaceous, 130 Ma | |
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Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | † Ichthyosauria |
| Family: | † Ophthalmosauridae |
| Subfamily: | † Platypterygiinae |
| Genus: | † Simbirskiasaurus Ochev and Efimov, 1985 |
| Species | |
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Simbirskiasaurus is an extinct genus of ichthyosaur from the Early Cretaceous (early Barremian) of Ulyanovsk Oblast, Russia. [1] [2] Its type specimen is YKM 65119, a fragmentary skull and vertebral column. [3]
Simbirskiasaurus was a small ichthyosaur, measuring 3.5 metres (11 ft) in length and 200 kilograms (440 lb) in body mass. [4] Fischer et al. give the diagnosis of Simbirskiasaurus as follows: "Platypterygiine ophthalmosaurid characterized by the following autapomorphies: external naris divided by a nasomaxillary pillar; posterior opening of the narial complex with anteroposteriorly constricted dorsal extension; deeply interdigitating prefrontal–lacrimal suture [reminiscent of the basal neoichthyosaurian Temnodontosaurus platyodon (Conybeare, 1822); see Godefroit, 1993]. Simbirskiasaurus birjukovi is also characterized by the following unique combination of features: subnarial process of the premaxilla reaches the posterior margin of the external naris (shared with Cryopterygius kristiansenae Druckenmiller et al., 2012); elongated anterior process of the maxilla, reaching anteriorly the level of the nasal [unlike in Aegirosaurus leptospondylus Bardet & Fernández, 2000 and Sveltonectes insolitus (Fischer et al., 2011b)]; pres- ence of a supranarial process of the premaxilla [shared with Platypterygius australis (McCoy, 1867), see Kear, 2005, and possibly Pervushovisaurus bannovkensis (Arkhangelsky, 1998b)]." [2]
The following cladogram shows a possible phylogenetic position of Simbirskiasaurus in Ophthalmosauridae according to the analysis performed by Zverkov and Jacobs (2020). [5]
| Ophthalmosauria |
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Ophthalmosaurus is an ichthyosaur of the Jurassic period. Possible remains from the Cretaceous, around 145 million years ago, are also known. Named for its extremely large eyes, it had a 6 metres (20 ft) long dolphin-shaped body with jaws containing many small but robust teeth. Major fossil finds of this genus have been recorded in Europe with a second species possibly being found in North America.
Platypterygius is a historically paraphyletic genus of platypterygiine ichthyosaur from the Cretaceous period. It was historically used as a wastebasket taxon, and most species within Platypterygius likely are undiagnostic at the genus or species level, or represent distinct genera, even being argued as invalid. While fossils referred to Platypterygius have been found throughout different continents, the holotype specimen was found in Germany.
Plutoniosaurus is an extinct genus of ophthalmosaurid ichthyosaur from the Early Cretaceous of the vicinity of Ulyanovsk, European Russia.
Caypullisaurus is an extinct genus of large platypterygiine ophthalmosaurid ichthyosaur from the Late Jurassic to the Early Cretaceous of Argentina. Its holotype was collected from the Vaca Muerta Formation of Cerro Lotena, Neuquen, dating to the early Tithonian stage of the Late Jurassic, about 150 million years ago. Caypullisaurus was first named by Marta Fernández in 1997 and the type species is Caypullisaurus bonapartei.
Ophthalmosauridae is an extinct family of thunnosaur ichthyosaurs from the Middle Jurassic to the early Late Cretaceous worldwide. Almost all ichthyosaurs from the Middle Jurassic onwards belong to the family, until the extinction of ichthyosaurs in the early Late Cretaceous. Opthalmosaurids appeared worldwide during early Bajocian, subsequent to the disappearance of most other ichthyosaur lineages after the end of the Toarcian. Currently, the oldest known ophthalmosaurids is Mollesaurus from the early Bajocian of Argentina, as well as indeterminate remains of the same age from Luxembourg and Canada. Named by George H. Baur, in 1887, the family contains the basal taxa like Ophthalmosaurus. Appleby (1956) named the taxon Ophthalmosauria which was followed by some authors, but these two names are often treated as synonyms; Ophthalmosauridae has the priority over Ophthalmosauria. However, some researchers argue that Ophthalmosauridae should be restricted to the group typically referred to as Ophthalmosaurinae, with classic Platypterygiinae instead being referred to as Undorosauridae or Brachypterygiidae and Ophthalmosauria being used to unite these two groups.
Brachypterygius is an extinct genus of platypterygiine ophthalmosaurid ichthyosaur known from the Late Jurassic of England. The type species was originally described and named as Ichthyosaurus extremus by Boulenger in 1904. Brachypterygius was named by Huene in 1922 for the width and shortness of the forepaddle, and the type species is therefore Brachypterygius extremus. The holotype of B. extremus was originally thought to be from the Lias Group of Bath, United Kingdom, but other specimens suggest it more likely came from the Kimmeridgian Kimmeridge Clay of Kimmeridge Bay, Dorset, UK.
Undorosaurus is an extinct genus of ophthalmosaurid ichthyosaur known from western Russia, Svalbard, and Poland.
Mollesaurus is an extinct genus of large ophthalmosaurine ophthalmosaurid ichthyosaur known from northwestern Patagonia of Argentina.
Grendelius is a genus of platypterygiine ophthalmosaurid ichthyosaur from the Late Jurassic (Kimmeridgian-Tithonian) of the UK and European Russia.
Maiaspondylus is an extinct genus of platypterygiine ophthalmosaurid ichthyosaurs known from Northwest Territories of Canada, the Cambridge Greensand of England and the Voronezh Region of Russia.
Arthropterygius is a widespread genus of ophthalmosaurid ichthyosaur which existed in Canada, Norway, Russia, and Argentina from the late Jurassic period and possibly to the earliest Cretaceous.
Athabascasaurus is an extinct genus of platypterygiine ophthalmosaurid ichthyosaur known from Alberta, Canada.
Sveltonectes is an extinct genus of platypterygiine ophthalmosaurid ichthyosaurs known from Ul’yanovsk region, western Russia.
Acamptonectes is a genus of ophthalmosaurid ichthyosaurs, a type of dolphin-like marine reptiles, that lived during the Early Cretaceous around 130 million years ago. The first specimen, a partial adult skeleton, was discovered in Speeton, England, in 1958, but was not formally described until 2012 by Valentin Fischer and colleagues. They also recognised a partial subadult skeleton belonging to the genus from Cremlingen, Germany, and specimens from other localities in England. The genus contains the single species Acamptonectes densus; the generic name means "rigid swimmer" and the specific name means "compact" or "tightly packed".
Platypterygiinae is an extinct subfamily of ophthalmosaurid thunnosaur ichthyosaurs from the early Late Jurassic to the early Late Cretaceous of Asia, Australia, Europe, North America and South America. Currently, the oldest known platypterygiine is Brachypterygius. Platypterygiines were characterized by square tooth roots in cross-section, an extremely reduced extracondylar area of the basioccipital, prominent dorsal and ventral trochanters on humerus and ischiopubis lacking an obturator foramen.
Leninia is an extinct genus of basal ophthalmosaurine ichthyosaur known from the late Early Cretaceous of western Russia. Leninia was first named by Valentin Fischer, Maxim S. Arkhangelsky, Gleb N. Uspensky, Ilya M. Stenshin and Pascal Godefroit in 2013 and the type species is Leninia stellans. It was named for Vladimir Lenin, one of the leaders of the Communist Revolution in Russia, as the museum it is currently housed in is also named for him.
Sisteronia is an extinct genus of platypterygiine ophthalmosaurid ichthyosaur known from the 'middle' Cretaceous of southeastern England and southeastern France. It contains a single species, Sisteronia seeleyi.
Pervushovisaurus is a genus of platypterygiine ichthyosaur from the Late Cretaceous (Cenomanian) of the Saratov region in western Russia and the Cambridge area of the UK.
Muiscasaurus is an extinct genus of ophthalmosaurid Ichthyosaur that lived in modern Colombia during the Early Cretaceous. The only known species is the type Muiscasaurus catheti.
Acuetzpalin is an extinct genus of platypterygiine ophthalmosaurid ichthyosaur found in the Kimmeridgian La Casita Formation in Mexico. It is known from a partial skeleton, of which the skull is surprisingly well preserved. It was the first ichthyosaur described in 2020 and the first new ichthyosaur genus described since 2017.
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