Pistosaurus longaevus is marine reptiles extinct genus belonging sauropterygia plesiosauria fossil found in France, Germany, the Middle Triassic strata. Pistosaurus estimated length of about 3 meters long. Pistosaurus originally classified as advanced nothosauroidea, nothosauroidea Triassic aquatic reptiles, was presumably plesiosauria ancestors.
Pistosaurus longaevus skull (cast)
Description and paleobiology[]
Restoration of Pistosaurus longaevus
Pistosaurus was about 3 meters (10 ft) long, and had a body form resembling that of nothosaurs, aquatic reptiles that flourished during the Triassic. However, the vertebral column was stiff, like that of a plesiosaur, implying that the animal used its paddle-like flippers to propel itself through the water, as the plesiosaurs probably did. The head also resembled that of a plesiosaur, but with the primitive palate of a nothosaur, and numerous, sharp teeth ideal for catching and eating fish.[1]
Although it is unlikely that Pistosaurus was a direct ancestor of the plesiosaurs, the mixture of features suggests that it was closely related to that group.[1]
Classification[]
Limb bone
Although it is unlikely that Pistosaurus was a direct ancestor of the plesiosaurs, the mixture of features suggests that it was closely related to that group.
The following cladogram follows an analysis by Ketchum & Benson, 2011.
The classification for Plesiosauria was difficult at the first place. The anatomy of stem group Sauropterygia has very primitive synapomorphies such as dermal palate. Initially, Plesiosauria were suggested related to Pistosauroidea, which belongs to Eusauropterygia from Triassic. Three genera of Plesiosauria was known in the history: Corosaurus alvocensis, Cymatosaurus, and Pistosaurus longaevus. A later discovery of a new Pistosauridea from middle triassic of Nevada by paleontologist Sander indicates that Augustasaurus is closely related to Pistosaurus, while there are several difference including axial skeleton.
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Historical information and discovery[]
The non-Plesiosaurian Sauropterygians are found in various locations in China, Europe, America, Palestine and Tunisia. Although Nothosaurus, which is closely related to Pistosaurus, are found plenty across Europe, Pistosaurus skull is only found in Germanic basin in Upper Muschelkalk.
The early discovery of Pistosaurus skull was by H. v. Meyer. He discovered two skulls and a postcranial skeleton at the same location, possibly from Pistosaurus. Later after that, a new and well preserved postcranial skeleton was also found at the same location as previous specimens. Paleontologist Geissler first described the skeletons and then paleontologist Strunz developed new hypothesis based on that. This skeleton was originally preserved at Strunz collection in Senckenberg Museum at Frankfurt a/M.
Although Pistosauroidea has long been considered as structural antecedents of Plesiosauria, a new specimen of Augustasaurus discovered by paleontologist Sandra from Nevada had raised to against this theory. Opposed to previous hypothesis, the forelimb of Augustasaurus was greatly reduced compared to Plesiosaurus. Therefore, Pistosauroidea was removed from stem group Plesiosauria and becomes paraphyletic group to Plesiosauria.
Avascular necrosis, also known as bone necrosis, is associated with decompression syndrome (DCS). It is caused by expose rapid decrease of external pressure as well as rapid ascent in water column. There features are often recognized in Triassic Sauropterygians. According to paleontologist Surmik, the presence of decompression syndrome-related avascular necrosis in Pistosaurus forelimb suggested that Pistosaurus used to live in aquatic or semi-aquatic environment. He also stated the possibility of Pistosaurus distributed in open marine cold water, and their effective metabolism is one of the reasons why Pistosaurus can survive the open sea.
Appearance in other media[]
Jurassic Park[]
- Pistosaurus makes an appearance in Jurassic Park III: Park Builder
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Read more Pistosaurus on Jurassic Park Wiki |