Sapheosaurus (Meyer 1850, Kimmeridgian Late Jurassic, France) has been known and largely ignored for a long time. Two species of this large sphenodontian are identified, S. laticeps with 22 presacrals and S. thiollierei with 26.
Adding Sapheosaurus to the large reptile tree nests it between Brachyrhinodon and the higher rhynchocephalians, Trilophosaurus, Mesosuchus and the rhynchosaur, Hyperodapedon. Conventinal thinking nests rhynchosaurs and trilophosaurs at the base of the archosauriformes, close to Prolacerta, but no series of archosauromorph taxa share so many traits.
Of course, there’s a time problem.
Rhynchosaurs and trilophosaurs were Triassic and Sapheosaurus is Late Jurassic. Of course, sphenodontians are well know for their phylogenetic longevity, with New Zealand’s own Sphenodon outlasting all of its former contemporaries.
In the Rauhut et al. (2012) tree (Fig. 3) they include many more sphenodontians than in the large reptile tree. Unfortunately they used the archosauromorph, Youngina, as an outgroup. It’s not related. Using Squamata was also ill-advised. After tall, which traits from which taxa would you cherry-pick? As in the large reptile tree, Brachyrhinodon and Sapheosaurus are close to one another. No rhynchosaurs or trilophosaurs are included in the Rauhut et al. tree, so, unfortunately, we will never see how they would nest there.
The palate of Kallimodon is interesting
because it demonstrates the side-by-side teeth that make the higher (but earlier) taxa so interesting (see Fig. 3 caption). Brachyrhinodon has similar parallel palatine teeth.
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