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Re: bipedality in pterosaurs (was:climbing dromaeosaurs and friends)

-----Original Message-----
From: Scott Hartman <scott_hartman@hotmail.com>
To: luisrey@ndirect.co.uk <luisrey@ndirect.co.uk>;
gigi.babcock@alumni.usc.edu <gigi.babcock@alumni.usc.edu>; dinosaur@usc.edu
Date: Thursday, December 07, 2000 9:25 PM
Subject: Re: climbing dromaeosaurs and friends

All of the Archeo specimens, despite their myriad
>preservational positions, preserve the hind limbs in a parasagital plane
>(even when the forelimbs aren't).  Yet the far majority of articulated
>Solenhofen pterosaurs are preserved with the hind limbs in separate planes
>of articulation.  Clearly something functional is different between these

Certainly, the late Jurassic pterosaurs found in the Solnhofen limestone
represent a good deal of evolutionary development and specialization of the
pterosaur form. It is my opinion that the earlier pterosaurs of the Triassic
might more closely resemble the basic theropod form.  From what I`ve read, I
gather that Padian sees all pterosaurs as being capable of bipedal
locomotion, whereas Unwin declares them all to be quadrupedal on the ground.
I myself would compromise by saying that Dimorphodon and other earlier
pterosaurs were capable of bipedal locomotion, and that later forms lost
this capability.

If one considers BCF, there exist many examples of secondarily flightless
theropods from the Triassic right on through to present time. One might
expect the same for pterosaurs, however, I can only see a couple of
candidates for secondarily flightless pterosaurs ...Scleromochlus and
Lagosuchus, both Triassic. Perhaps the lack of others beyond the Triassic
reflects the loss of bipedal ability in the later pterosaurs.