Re: PTEROSAURS: AVIAN ANCESTORS?

["Jaime A. Headden" <qilongia@yahoo.com>]

Larry Febo wrote:

<<I`m not sure if these details aren`t related to the more powerful
musculature needed by these pterosaurs to move their enormous wings
without collapsing the ribcage. These might be  the features expected
in a
more advanced, and hence specialized form, not the more primitive,
generalized form that birds might have evolved directly from. Even
Wellnhofer states how even the earliest pterosaurs recorded seem
already specialized to their particular mode of flight , and a great
gap existing in the fossil record as to what exactly led up to the
first pterosaurs,(as we know them).>>

Betty Cunningham wrote:

<What kinda shoulder girdle did rhemphorynchinoids have?  How similar
are they to the later pterosaurs? If the smaller earlier forms have
the same shoulder details as the later more powerful forms, it won't
fit your theory. They would not have evolved to handle heavier
musculature if they evolved FIRST, BEFORE the heavy musculature.>

  Yes, the basal pterosaurs possess a sternum that, like Matt said, is
stepped: one coracoid (the right one, I believe) is in front of the
other, behind the cristospina.

  Additionally, advanced pterosaurs of the pteranodon-grade have a
notarium that locked the distal ends of the scapulae together; this
would have performed the rigid anchors for the muscles that birds have
thanks to their specialized pectoral girdles.

  Also, there is a pteroid bone in pterosaurs that is not analogous to
any bird bone, especially not the alula.

  I'm working on basal pterosaurs as a past-time, and I'd like to say
that the skull of *Preondactylus*, the most basal of them all, is
nothing like a lizard, and more similar to the pre-dinosauromorph form
than to lepidosaurs or even prolacertforms (as far as I've seen yet,
and I'll admit I haven't seen much detail applied), as the skulls of
*Megalancosaurus* and *Cosesaurus* are just _wierd_ compared to
anything else.

==
Jaime A. Headden

Qilong, the website, at:
http://members.tripod.com/~Qilong/qilong.html
---
All comments and criticisms are welcome!

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