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Re:prolacertiformes as arboreal leapers,...was: ABSRD BAND on Sinornithosaurus feathers



-----Original Message-----
From: Dinogeorge@aol.com <Dinogeorge@aol.com>
To: dinosaur@usc.edu <dinosaur@usc.edu>
Date: Thursday, March 15, 2001 11:16 AM
Subject: Re: ABSRD BAND on Sinornithosaurus feathers


>In a message dated 3/15/01 10:37:39 AM EST, rob_redwing@hotmail.com writes:
>
><< Has anyone here actually seen Longisquama? >>
>
>Dave Peters has produced the best figures of Longisquama yet published
>anywhere:
>
>Peters, D., 2001. "A reexamination of four prolacertiforms with
implications
>for pterosaur phylogenesis," Revista Italiana di Paleontologia e
Stratigrafia
>106(3): 293-336.
>
>He shows that Longisquama, Cosesaurus, Sharovipteryx, and pterosaurs are
all
>derived prolacertiforms and not archosaurs. I have almost no doubt he is
>correct. He also has the best figures of Sharovipteryx and Cosesaurus yet
>published anywhere, all based on his own microscopic examinations of the
>actual specimens. Very thoroughly done! This paper, years in the writing,
is
>a must read for everyone on the dinosaur list.
>

I agree with George that Dave Peters makes an excellant case for a close
kinship between prolacertiformes and pterosaurs.Although he mentions many
common morphological traits that link longisquama with this group, he does
not have much to say about those long "feathers" it sports along its back
(unfortunately, cause I would like to hear his opinion about them). They are
not among the traits used in the cladistic analysis. (in fact, he does not
even show their complete extent in his diagram). He does mention,
however,that they may be analogous to the rectangular flaps seen along the
back of Cosesaurus.

The prolacertiforms seem an amazingly odd group in their extreme
diversification of form. It seems (to me) that they were most likely
arboreal (for the most part), and might have been experimenting with varios
forms of gliding, or parachuting behavior. Sharovipteryx with it`s rearward
patagium, and longisquama with those long fronds may just represent
different adaptations to an aboreal leaping condition.Although there is no
direct positive fossil evidence, if these forms were pterosaur ancestors, I
wouldn`t be surprised if many of them had patagia, and the ability to glide.
Dave Peters calls the prolacertiforms "terrestrial" forms. Although by this
(I`m sure) he didn`t mean they didn`t climb trees, I would go one step
further, and call ,the majority of the group "arboreal". IMHO.