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Re: Let's find the basal Ornithodire.
this, I suppose, is worth addressing again. Much of what you're looking for is
in an earlier Prehistoric Times, and copied to my website as a pdf file.
> However, the more critical issue, and which has eluded paleontology --
> and even Dave's techniques and researches -- has been a "pro-pterosaur"
> that shows a long arm with modifications towards flight,
No, it hasn't eluded my research.
The long arm is the last thing that shows up. After most everything else is in
place. But note the juvenile phase in Longisquama has relatively longer arms
and shorter legs, as in pteros.
> as in broadening
> of the sternum,
Sorry to have to repeat this yet again.
As in Longisquama. Not exposed in Sharovipteryx.
> formation of a keel,
As in Longisquama and Cosesaurus. Not exposed in Sharovipteryx.
> elongation of the arm,
covered above. shows up in juvie Longi.
> and expansion of the sacrum,
by this you mean solidification of the ventral pelvis? If so, shows up in
Cosesaurus + L + S.
by this you mean expansion of the anterior process of the ilium? If so, ditto
> "locking" of the dorsal spine,
not sure if anything in the dorsal spine is locked up in basal pteros. Curious
about this though. Please explain.
> closure of
> carpal contacts into sutures or fusing of the elements,
They don't close up in basal pterosaurs. See Peters 2001. Historical Biology
> reduction of the
> proximal metacarpals (I-III) relative to the fourth,
Actually its the elongation of the fourth metacarpal relative to I-III. That's
in L + S. And are there such things as proximal metacarpals? Did you mean
proximal carpals? If so, that's probably present in Longisquama, but it's a bit
around the wrist. And tiny.
> elongation of the
> fourth metacarpal and digit,
In L + S. See pterosaurinfo.com
> lateral rotation of the scapulocoracoid and
> thereby also the humeral glenoid (and why Dave's theory of the humerus
> laying parallel to the trunk does NOT work),
Am I the Dave you are referring to? If so, can lizards draw the humerus close
to the trunk? If so, then Longisquama and Sharovipteryx could. In pterosaurs
things change abit. Hard to tell in basal taxa like MPUM 6009, but not a big
head there on the humerus. But jump up to Eudimorphodon and a large medial head
prevents close adduction, I imagine. Haven't built the model to test it though.
> etc.. So far, no such animal
> exists, including the "prolacertiforms," "protorosaurs," and any of Dave's
> proposed ancestors.
> Even *Sharovipteryx* shows exactly the opposite of the
> brachial modifications, getting SHORTER than the leg, with protraction of
> leg elements, showing this is not even close enough to an ancestor to
> counter the "ornithodiran" features.
Ah, Luke...look beyond the obvious. Start with the toes. Do your cladogram. Let
PAUP guide you. Sharovipteryx even has a long neck. It's going off in another
direction. Still, PAUP says it's a sister taxon. Closer than almost anything
known to exist.
More importantly, if a taxon fulfilled ALL of your requirements, guess what, it
would be a pterosaur! You have to allow for something to evolve from "not a
pterosaur" to "a pterosaur". Think about the theropod-bird connection and make
the parallels in your mind work to accept this. Or try a cladogram.
> To date, however, many ornithodiran
> synapomorphies, including the "s-curved" neck, have been over-ridden by
> basal dinosauromorph taxa, even if one includes *Scleromochlus.*
Not sure that basal pterosaurs (MPUM 6009) can claim to have an S-curved neck.
It's quite short. Identical to the one in Longisquama. Later ones don't count
in this case because you're looking for basal synapomorphies.
Hope this helps,
> Jaime A. Headden
> Little steps are often the hardest to take. We are too used to making
> leaps in the face of adversity, that a simple skip is so hard to do. We
> should all learn to walk soft, walk small, see the world around us rather
> than zoom by it.
> "Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
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