Re: Details on SVP 2001 Friday talks

[Nick Longrich <longrich@alumni.princeton.edu>]

Title: Re: Details on SVP 2001 Friday talks

> Nick Longrich wrote-
> Sinraptor also appears to have had a
> pubic foramen, unlike Allosaurus which lacks the foramen, as in
> coelurosaurs. If you threw more taxa into this matrix, and then a few
> more characters,  you'd probably start seeing several different
> carnosaur groupings.
>  
> Ah, the old
> idea of allosaurids being closer to coelurosaurs than sinraptorids and
> carcharodontosaurids.  Replaced by the new consensus of all three
> groups in a Carnosauria.  Sinraptor dongi has an open obturator
> notch, as do your more basal Acrocanthosaurus and Giganotosaurus. 
> On the other hand, the Santana compsognathid has an obturator foramen
> in one pubis.  Confusing situation, as usual.  Then there's
> your placement of carcharodontosaurids by sinraptorids, not
> allosaurids, opposite of the current consensus.  Personally, I
> like a Carnosauria including sinraptorids and a
> carcharodontosaurid-allosaurid clade, with torvosaurs and spinosaurs
> further down, but it's not like I've run an
> analysis.

        Well, Sinraptor dongi has an elongate flange reaching around so as to almost close the pubic fenestra; looking at the casts it makes it look likely that in life the thing was actually closed. Sinraptor (Yangchuanosaurus) hepingensis is illustrated with a closed pubic fenestra. As for the other guys, I can't say, haven't seen the material, but I tend to distrust illustrations (Afrovenator being just one of many examples why). The skulls are about the only things that are really well illustrated across most of these animals, but if they're illustrated accurately they do seem to show a suite of characters- things like the overhanging postorbital boss, expanded prefrontal, lip-like edge to the ventral margin of the antorbital fenestra, mental foramena of the dentary set in a well-defined groove- which could tie them together.

        Regarding troodontids, for the most part they seem to be every bit as birdlike as the dromaeosaurids.  Another problem is Rahonavis; I think that there are a number of remarkably dromaeosaurid-like features which were not included in the initial analyses, enough to make a real difference in where they come out. One kind of weird thing- Sinornithoides seems to have an extraordinarily narrow head- rather similar to that "bladelike" snout that Velociraptor has.

        -N