A new Nature paper
by Jiang et al. 2016 introduces Sclerocormus, a large sister to the much smaller Cartorhynchus. Like a marine Cotylorhynchus, this odd basal sauropterygian had a tiny skull not much larger than that of its much smaller, big-headed sister (Fig. 1).
These two nested
with Qianxisaurus, a basal sauropterygian/pachypleurosaur, not basal ichthyosauriforms. The authors are still in the dark about ichthyosaur ancestors. You can trace them, or any taxon, back to basal tetrapods here.
report that Sclerocormus had no teeth and that the nasals extended to the tip of the rostrum. I have to disagree with both observation given the photographic data and lack of similarity in sister. They also misidentified a few bones. Their big scapula is a posterior coronoid + smaller scapula.
More coming in later posts.
Jiang D-Y, Motani R, Huang J-D, Tintori A, Hu Y-C, Rieppel O, Fraser NC, Ji C, Kelley NP, Fu W-L and Zhang R 2016. A large aberrant stem ichthyosauriform indicating early rise and demise of ichthyosauromorphs in the wake of the end-Permian extinction. Nature Scientific Reports online here.