A new nothosaur (Sauropterygia) from the Ladinian of Vellberg-Eschenau, southern Germany

A new species of <i>Nothosaurus</i> from the Lower Keuper (Lettenkeuper, Ladinian, Erfurt Formation) of Vellberg-Eschenau, southern Germany, is described on the basis of a nearly complete skull that is only missing the lower jaw. Together with <i>Nothosaurus edingerae</i>, it is the only valid <i>Nothosaurus</i> species exclusively known from the Lower Keuper (Ladinian) of the Germanic Basin. <i>Nothosaurus cristatus</i>, sp. nov., differs from all other nothosaurs by exhibiting a postorbital that is excluded from the orbital margin by the postfrontal, the maxilla, and the jugal. The postfrontal and the maxilla form the posterior orbital margin exclusively. The parietal forms a pronounced and sharp crest anterior to the parietal foramen, which is unique among <i>Nothosaurus</i>. The ectopterygoid bears a long posterior process. A phylogenetic analysis of <i>Nothosaurus cristatus</i>, based on Liu et al. (2014, Scientific Reports 4:7142, doi: 10.1038/srep07142) with modified characters after Lin et al. (2017, Journal of Vertebrate Paleontology, doi: 10.1080/02724634.2017.1278703), yielded a nearly unchanged topology that supported the monophyly of (<i>N</i>. <i>jagisteus</i> (<i>N. cristatus</i> (<i>N. mirabilis</i> + <i>N. tchernovi</i>))).