Re: SEGNOSAUR 2

[Dinogeorge <Dinogeorge@aol.com>]

In a message dated 98-04-12 03:17:36 EDT, jaemei@hotmail.com writes:

<< <The pneumaticized basisphenoid is a segnosaur autapomorphy.>
 
 Actually, it's an *Erlikosaurus* autapomorphy, as only this genus of 
 this group is known with a braincase; when a different skull pops up 
 with this feature, then it becomes an autapomorphy of that next upper 
 taxon which will include Erliko and "unnamed segnosaur". >>

While it is possible that only _Erlikosaurus_ of all segnosaurs had a
pneumaticized basisphenoid, I hardly think that's likely. (If you're going to
get picky like this, it is even possible that the very skull we have found is
the only segnosaur skull that ever had such a basisphenoid--a one-time
mutation that we have chanced upon.) The kind of basisphenoid that
_Erlikosaurus_ had is not known in any other dinosaur groups, so it is fair to
call it a segnosaur autapomorphy even if we have only one segnosaur specimen
that displays it.