Editing Xinpusaurus
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''Xinpusaurus'' is a thalattosaur, a group of triassic marine reptiles with long, paddle-like tails and short legs with independently movable digits. Specifically, it is a member of the group thalattosauroidea, which are characterized by their downturned [[premaxilla]]e. ''Xinpusaurus'' had a short neck, a massive [[Quadrate bone|quadrate]], and one of the few braincases preserved in thalattosaurs. The lower jaws of this genus show two different forms of [[dentary]]-[[Suprangular|surangular]] sutures, either a v-shaped suture with the surangular cutting into the dentary from the side (type 1) or an oblique suture with the surangular underlying the dentary (type 2). ''X. bamaolinensis'' preserves a type 2 suture while ''X. kohi'' has a type 1 suture. ''X. suni''<nowiki/>'s suture differs between specimens while ''X. xingyiensis'' seems to have a type 2 suture.<ref name="LJ13" /> The dentary is also narrow and shorter than the snout, with robust, pointed teeth in the front of its jaws and broad crushing teeth in the back of its jaws, suggesting that it fed on hard-shelled prey, although these adaptations are not as extreme as those of ''[[Concavispina]]'', which had exclusively short and blunt teeth.<ref name="LZLH13">{{Cite journal|last1=Liu|first1=J.|last2=Zhao|first2=L. J.|last3=Li|first3=C.|last4=He|first4=T.|year=2013|title=Osteology of ''Concavispina biseridens'' (Reptilia, Thalattosauria) from the Xiaowa Formation (Carnian), Guanling, Guizhou, China|journal=Journal of Paleontology|volume=87|issue=2|pages=341|doi=10.1666/12-059R1.1|bibcode=2013JPal...87..341L |s2cid=83684967}}</ref> This genus also has a uniquely upward-curving [[maxilla]], a wide proximal end of the [[humerus]], and a [[Radius (bone)|radius]] with a convex lateral edge and concave medial edge.<ref name=":1" /> |
''Xinpusaurus'' is a thalattosaur, a group of triassic marine reptiles with long, paddle-like tails and short legs with independently movable digits. Specifically, it is a member of the group thalattosauroidea, which are characterized by their downturned [[premaxilla]]e. ''Xinpusaurus'' had a short neck, a massive [[Quadrate bone|quadrate]], and one of the few braincases preserved in thalattosaurs. The lower jaws of this genus show two different forms of [[dentary]]-[[Suprangular|surangular]] sutures, either a v-shaped suture with the surangular cutting into the dentary from the side (type 1) or an oblique suture with the surangular underlying the dentary (type 2). ''X. bamaolinensis'' preserves a type 2 suture while ''X. kohi'' has a type 1 suture. ''X. suni''<nowiki/>'s suture differs between specimens while ''X. xingyiensis'' seems to have a type 2 suture.<ref name="LJ13" /> The dentary is also narrow and shorter than the snout, with robust, pointed teeth in the front of its jaws and broad crushing teeth in the back of its jaws, suggesting that it fed on hard-shelled prey, although these adaptations are not as extreme as those of ''[[Concavispina]]'', which had exclusively short and blunt teeth.<ref name="LZLH13">{{Cite journal|last1=Liu|first1=J.|last2=Zhao|first2=L. J.|last3=Li|first3=C.|last4=He|first4=T.|year=2013|title=Osteology of ''Concavispina biseridens'' (Reptilia, Thalattosauria) from the Xiaowa Formation (Carnian), Guanling, Guizhou, China|journal=Journal of Paleontology|volume=87|issue=2|pages=341|doi=10.1666/12-059R1.1|bibcode=2013JPal...87..341L |s2cid=83684967}}</ref> This genus also has a uniquely upward-curving [[maxilla]], a wide proximal end of the [[humerus]], and a [[Radius (bone)|radius]] with a convex lateral edge and concave medial edge.<ref name=":1" /> |
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''X. bamaolinensis'' and ''X. kohi'' had particularly elongated premaxillae, forming a narrow and pointed [[Rostrum (anatomy)|rostrum]]. However, the specimens with the longest snouts are also the smallest in other proportions, so this may be a juvenile trait and cannot be used to distinguish these species from ''X. suni''.<ref name="LJ13" /> |
''X. bamaolinensis'' and ''X. kohi'' had particularly elongated premaxillae, forming a narrow and pointed [[Rostrum (anatomy)|rostrum]]. However, it should be noted that the specimens with the longest snouts are also the smallest in other proportions, so this may be a juvenile trait and cannot be used to distinguish these species from ''X. suni''.<ref name="LJ13" /> |
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''X. xingyiensis'' is the largest species known and is also probably the least advanced, as it does not have a posterior process of the jugal unlike the other species and shares some similarities with the genus ''Concavispina''.<ref name=":1" /> |
''X. xingyiensis'' is the largest species known and is also probably the least advanced, as it does not have a posterior process of the jugal unlike the other species and shares some similarities with the genus ''Concavispina''.<ref name=":1" /> |