Mickey commented on my earlier post regarding the recent proclamation of a dinosauromorph specimen from the Induan of Germany. In my original post I stated that crocodile-line archosaurs were present in the Induan in the form of Proterosuchus (see picture below - from Wikipedia). Of course Proterosuchus is a basal archosauriform and NOT a archosaur. I wish that
I could state that this was based on new research that shows that proterosuchids were more derived than previously thought, but of course this is not the case. In fact in an upcoming publication on the enigmatic form Vancleavea (Parker and Barton, in press) we include a phylogenetic analysis that also supports proterosuchids as basal archosauriforms. Thus I really have no excuse except that I simply rushed the original post. Upon reflection, based mainly on Mickey's comment, I realize that there is a little more to say about this find.
The discovery of a dinosauromorph from the Induan (earliest Triassic) would not "fill in" ghost lineages as I said in my earlier post, but rather would extend the ghost lineages for erythrosuchids and euparkeriids back from the Olenekian (late Early Triassic) into the Induan. It would also extend the ghost lineage for proterochampsids and pseudosuchians back from the Ladinian (late Middle Triassic) and Anisian (early Middle Triassic) respectively to the Induan. As a result the ornithodirans would hypothetically appear first in the fossil record in respect for the pseudosuchians. The earliest known described ornithodiran is from the Ladinian.
In my opinion one of the most interesting aspects of the Triassic fossil record is the diversity found in the crocodile-line archosaurs and the bauplan similarities between many pseudosuchians and ornithodirans. In fact I am fond of telling my students that, because the first pseudosuchian appears in the Anisian and the first ornithodiran in the Ladinian, the dinosaurs were simply "crocodile wannabees". I may have to rethink this if this Induan find is confirmed.
Parker, W.G., and B.J. Barton. In Press. New information on the Upper Triassic archosauriform Vancleavea campi based on new material from the Chinle Formation of Arizona. Palaeontologia Electronica.
Turing's morphogenesis and the fingers' formation
16 hours ago in Doc Madhattan