Ancient Sea Reptiles, plesiosaur cladograms (Patreon)

Having done the plesiosaur images representing the main groups (see previous post), I've now arranged them into simplified cladograms to show our changing thoughts on how the groups might be allied. Above you see a 'modern' cladogram, based mostly on Benson & Druckenmiller (2013) but with a structure that owes much to proposals made by Bakker (1993) and then to work by O'Keefe and others. The main novelties here (emerging largely but not entirely from Benson & Druckenmiller (2013)) are that rhomaleosaurids are early-diverging and not on the pliosaurid lineage, and that the leptocleidid + polycotylid clade forms Xenopsaria with elasmosaurids.

This view is very different from the 'traditional' view that was in vogue for the mid-20th century. Here, Plesiosauria was thought to consist of Pliosauroidea and Plesiosauroidea, as follows...

Tidied, better-looking versions of these cladograms will be included in Ancient Sea Reptiles. I'm doing the near-final edit on the chapters now and will share some chunks of text in a little while.

More soon, all the best.