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Re: Whatever prima



In a message dated 97-04-15 14:47:36 EDT, th81@umail.umd.edu (Thomas R.
Holtz, Jr.) writes:

<< Nope.  Many of the critters that he's most excited about (aka,
 Megalancosaurus and the other drepanosaurids) may not even be
 archosauromorphs, much less true archosaurs. >>

Finally (at SVP) got a decent photo of the type specimen of _Megalancosaurus_
(since I can't afford a trip to Europe to see the specimen in person).
There's definitely an antorbital fenestra of some size, but the skull is
busted there, so one really can't do much better than say the fenestra
exists. The skull has a very archosaurian appearance and wouldn't be out of
place on a pterosaur or primitive dino-bird, for example. The neck vertebrae
change morphology abruptly at the cervicodorsal boundary, which is why, among
other things, it took so long to connect the head and neck of the type
specimen with the postcrania of the referred specimens. This is a strongly
diagnostic feature of Ornithodira within Archosauria, so _Megalancosaurus_
and other drepanosaurids may belong to a sister group of Dinosauria +
Pterosauria in Ornithodira.

I also urge people to take another look at the type vertebral column of
_Spinosuchus caseanus_, once classifed as a coelurian theropod. To me it
looks like a big drepanosaurid maybe 2 m long. Same vertebral morphology as
in the smaller _Drepanosaurus_, _Dolabrosaurus_, and _Megalancosaurus_. Too
bad the only drepanosaurid skull we have is on the type specimen of
_Megalancosaurus_; we could use a few more skulls for this family.