Re: DINOSAUR ARGUMENT: THE RESOLVE

[larrys@zk3.dec.com]

>As far as I understand, if an early dinosaur was found which could be shown
>to be an ancestor of an early pterosaur, then pterosaurs would be dinosaurs.

>But, I think this is unlikely. My reasoning behind this is that dinosaurs
>(unless I am mistaken, by definition) have an upright porsure. Pterosaurs
>have only a semi-upright posture.

By the usual reconstruction method, yes.  However, this places the
entire vast array of pterosaurs flat on their bellies when on the
ground.  This works for bats, but bats aren't identical in all
respects with what we know of pterosaurs.  There is a school of
thought that places pterosaurs upright, with wing membranes
connecting to hip rather than hind leg, giving them stances and
gaits nearly identical to modern birds.  I find these more plaus-
ible than the old reconstructions, myself, but all reconstructions
new and old are contingent upon confirmation of membrane attachment,
and that has not be definitively confirmed either way to my knowledge.
However, given the apparent connection between birds and dinosaurs,
I expect we should not be surprised to find one between dinosaurs and
pterosaurs - which would make dinosauria the only class to have devel-
oped flight more than once.

regards,
Larry Smith