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Re: New paper on the origin and early evolution of dinosaurs
David Peters <email@example.com> wrote:
> As long as you include Lagerpeton and Dromomeron, and
> especially pterosaurs, as dino-sisters, you're going to have
> trouble with the origin of dinos.
Sorry, I really don't get what you mean here. The positions of _Lagerpeton_
and _Dromomeron_ as "dino-sisters" (i.e., non-dinosaurian dinosauromorphs) are
recovered by phylogenetic analysis. I can't understand what could be gained by
excluding them from an analysis.
Speaking of pterosaurs, it's possible that the evolution of the pterosaur body
plan, especially the evolution of wings, occurred quite quickly. Such a rapid
transformation has been inferred for the bat (chiropteran) body plan, and used
to explain why we haven't yet found fossil evidence for the early stages of
flight development in this group (Sears et al., 2006; PNAS 103: 6581â6586).
It is therefore possible that pterosaurs might have branched off quite late,
around the same time as the dinosaurs. In fact, maybe pterosaurs are
themselves dinosaurs. I'm going to stick my neck out here and say that I
wouldn't be at all surprised if future analyses show pterosaurs to be nested
inside Saurischia. It would mean that the axial air sacs (and flow-through
respiratory system) shared by saurischians and pterosaurs have a single origin.
It's a crazy idea, I know. But not *that* crazy.
Returning to the actual paper, it's nice to see Silesauridae receive a formal
definition. It's also worth mentioning that several Triassic dinosaur taxa
mentioned by Langer &c have been hypothesized elsewhere (Ezcurra & Novas, 2009;
JVP 29: 92A) to belong to a new clade called the Guaibasauridae
(_Guaibasaurus_, _Panphagia_, _Saturnalia_, _Agnosphitys_), a radiation of