Belongs within: Eusauropterygia. The Plesiosauroidea are a clade of mostly long-necked (sometimes extraordinarily so) marine reptiles known from the Jurassic and Cretaceous periods. <==Plesiosauroidea |–Plesiosaurus de la Beche & Conybeare 1821H02, D07 [Plesiosauridae] | |–P. brachypterygius Huene 1923H02 | |–P. costatus Owen 1840B93 | |–P. dolichodeirus Conybeare 1824DV06 | |–P. eurymerusD07 | |–P. guilelmiimperatoris Dames… Continue reading Plesiosauroidea


Belongs within: Sauropterygia.Contains: Plesiosauroidea, Pliosauroidea. The Eusauropterygia are a clade of Mesozoic marine reptiles uniting the Plesiosauria with the Triassic nothosaurs. Synapomorphies (from The Plesiosaur Directory): Jaws and mandibular symphysis elongate (skull large); rostral dentition strongly procumbent with paired maxillary fangs; five premaxillary teeth present; orbit small relative to skull length; skull dorsoventrally depressed; upper… Continue reading Eusauropterygia


Belongs within: Lepidosauromorpha.Contains: Eusauropterygia. The Sauropterygia are a Mesozoic clade of marine reptiles including the plesiosaurs, placodonts and related taxa. Synapomorphies (from Schoch & Sues 2015): Premaxilla large, forming most of the snout; lacrimal restricted to orbit or absent; palate akinetic; angle of transverse flange of pterygoid less than 45° from sagittal plane; cervical ribs… Continue reading Sauropterygia