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Re: Pterosaurian Pedal Clinching (Batman! :) )

I wrote:

<<Given either of the two theories regarding pterosaur
evolution, one being the archosaur derivative, and the
other lepidosauriform>> [_sic_; this should read
"prolacteriform", as Holtz corrected] <<derived, both
have ancestors that could be and probably were,
scansorial or arboreal.>>

Larry Febo wrote:

<Gee,...I hate to point this out (after Dr Holtz
already corrected that post)...but...I gotta know! I
thought the archosaur derived theory had Lagosuchus
(or perhaps Scleromochlus)) as it`s prime candidate.
As Padian proposed it, these forms were considered to
be "cursorial", and that the evolution of pterosaurs
was from the "ground-up" as also proposed (by some)
for birds.>

  Uhm ... I'm not denying Padian's suggestion of
primary cursoriality in these animals, and I think I
said they seemed to be more cursorial than anything
else in a pervious post, as shown from Sereno and
Arucci (1992), as well as various Padian articles on
pterosaurs, Peters' work, and Welnhofer's book;
however, to clarify my meaning in the post above, I
suggested that the two lineages have basal members who
do still show features (including the ball-and-socket
hip or a form midway between spherical and
cylindrical, as in *Marasuchus*) plus broad scapular
blades apparently indicating independantly swinging
forelimbs, semi-grasping manus, very flexible
vertebrae, etc., that are quite numerous in arboreal
or scansorial animals (pers. obsv.; see also Carroll,
1988 [_Vertebrate Paleontology and Evolution_], for
those looking at books ... and that's all you need for
ILL ... it's under QE in LOC code.).

<Of course, ...there  may be others out there who
propose some arboreal archosaur led to pterosaurs,but,
if that`s the case, I`m unaware of it, and would like
to know what these alternate theories are, and what
are the refs.>

  This should be interesting to discover, but I'm sure
it goes far back. Early restorations of pterosaurs
included bat-like squatters that wouldn't climb,
armored like miniature crocodiles (check out Padian,
1989, in _Dinosaurs Past and Present_ {v. 2: 65-81}
for a quick review of changes in perceiving
pterosaurs, including various restorations over the
few centuries) so there should not be too much
problems on this field. However, Padian, followed by
Unwin and Paul, in numerous papers, have argued for
the intrinsic climbing _ability_ in pterosaurs, but
don't read exactitude into this (Padian, 1983:
_Postilla_ 189: 1-44, and 1983: _Paleobiology_ 9:
218-239; Unwin, 1987: _Nature_ 327: 13-14; Paul, 1987:
_Nature_ 328: 481, and 1989: _Dinosaurs Past and
Present_ v.2: 4-49) as they caution in places.

  I hope this clarifies to you my position on the
matter on lagosuchids and the proposed models for
arboreality in pterosaurs.

Jaime "James" A. Headden

"Come the path that leads us to our fortune."

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