What is Mesosaurus?
{{Taxobox |name = ''Mesosaurus'' |fossil_range = [[Permian]] 299 to 280 million years ago |image = Mesosaurus tenuidens 1.jpg |image_width = 250px |image_caption = ''Mesosaurus tenuidens'' | regnum = [[Animal]]ia | classis = [[Sauropsida]] | ordo = †Mesosauria | familia = †Mesosauridae |authority = Gervais, 1864-66 }} [[Image:Mesosaurus BW.jpg|thumb|220px|Life restoration of ''Mesosaurus''.]] [[Image:Snider-Pellegrini Wegener fossil map.svg|thumb|230px|Location of ''Mesosaurus'' remains shown in blue.]] '''''Mesosaurus''''' is an extinct [[Ocean|marine]] [[reptile]] from the early to late [[Permian]] of southern [[Africa]] and [[South America]]. It was one of the first known [[marine biology|marine]] reptiles, and had many [[adaptations]] to a fully [[aquatic]] [[lifestyle]]. It is sometimes considered an [[anapsid]],<ref>anapsid = no opening in the skull behind the eye socket</ref> but there is some disagreement about that.<ref name=GP08>{{cite journal |last=Huene |first=F. von |year=1940 |title=Osteologie und systematische Stellung von ''Mesosaurus'' |journal=Palaeontographica. Abteilung A. Palaeozoologie-Stratigraphie |volume=92 |pages=45–58}}</ref><ref name=vH1>{{cite book|last=Piñeiro|first=Graciela|chapter=Los mesosaurios y otros fosiles de fines del Paleozoico |editor=D. Perera|title=Fósiles de Uruguay|publisher=DIRAC, Montevideoy |year=2008}}</ref> It is described by Benton as a 'parareptile', that is, a [[sauropsid]].<ref name=MJB>Benton M.J. 2015. ''Vertebrate palaeontology''. 4th ed, Wiley Blackwell, p126.</ref> ==Palaeobiology== ''Mesosaurus'' was one of the first reptiles to return to the [[water]] after early [[tetrapod]]s came to land in the later [[Devonian]].<ref name=ML10>{{cite book|last=Laurin|first=Michel|title=How vertebrates left the water|url=https://archive.org/details/howvertebratesle0000laur|publisher=University of California Press|year=2010|edition=illustrated|pages=|isbn=978-0-520-26647-6}}</ref> It was around {{convert|1|m|ft}} in length, with webbed feet, a streamlined bod