Re: LET THE SYNAPOMORPHY WARS BEGIN! (REALLY, REALLY LONG)

[Dinogeorge@aol.com]

In a message dated 97-08-01 04:12:23 EDT, Tetanurae@aol.com writes:

<< The enlarged, pneumatic parasphenoid? >>

Just a quickie reply to this item. In _Erlikosaurus_, it is the BASISPHENOID
that is enlarged and pneumatic, >not< the parasphenoid. Look at the figure
and photo in Clark et al.'s paper. These basicranial elements are fused in
_Erlikosaurus_, but it is still possible to distinguish the >back< of the
basicranium, where the basisphenoid is, from the >front<!! _Erlikosaurus_
does >not< have the inflated >parasphenoid< capsule of troodontids and
ornithomimids (i.e., bullatosaurs), which is located at the front of the
basicranium behind the pointy cultriform process. In ornithomimosaurs, the
parasphenoid capsule has a ventral opening; in troodontids, the capsule is
closed (and smaller). The capsule is quite absent from _Erlikosaurus_, and
the cultriform process seems to be integrated into the palatal vault (weird,
but that's how they sketch it).

If you read the paper, you'll see that the description of the pneumaticity
starts out by calling the pneumaticized element a basisphenoid, then shifts
to calling it a "parabasisphenoid" (because of the fusion of the two
elements), and thus we finally got an "inflated parasphenoid" in segnosaurs
where there was none.

Addendum: My copy of the Clark et al. paper is still back in Buffalo, so I'm
going by memory here and cannot recheck my reading just now. As I recall,
this was one of several apparent descriptive and taxonomic errors I found in
that paper.

More later...