Re: Information on Pelecanimimus

[Dinogeorge@aol.com]

In a message dated 97-06-16 19:09:50 EDT, martz@holly.ColoState.EDU (Jeffrey
Martz) writes:

<< The major disagreement I have with BCF is its avoidance of
 convergence; it seems to claim that any archosaur or near archosaur that
 may have flown or been arboreal had to be closely related to birds.  There
 is no shortage in the modern world  of gliding animals; mammals, frogs,
 lizards, and even snakes (!).  What is so hard to believe about gliders
 and tree dwellers evolving among the archosaurs numerous times during the
 Triassic, especially considering they otherwise don't seem have
 much in common?     >>

Your final sentence is exactly what I've been asking for several years
now...!

You're laboring under a misconception here. Certainly there may have been
many arboreal or nearly arboreal archosaurs that never evolved into birds
(e.g., how about the proto-pterosaurs?), and BCF cheerfully admits the
possibity that arboreality developed independently in several archosaurian
groups; the more the merrier, and so much the better the chance that >one< of
those groups continued to evolve and eventually gave rise to birds.

_Longisquama_, however, shares the characters "furcula present" and
"featherlike dermal structures present" with theropods--both characters
surely absent in sauropodomorph and ornithischian dinosaurs, in which the
clavicles, when present or known, are never fused into a furcula (the
primitive state), and the dermal structures are bony (the primitive state).
Furthermore, the _Longisquama_ furcula is remarkably similar to the furcula
of allosaurid theropods, oviraptorids, and enantiornithan birds. Unless
>both< characters evolved >together< twice (a long shot, though not
impossible)--once in an independent _Longisquama_ lineage and once again in
theropods, _Longisquama_ is a theropod.