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Re: BANDS > PADS vs. PALS
Offhand, Anchisaurus (holotype) (Cope 1870) and the indeterminate East Windsor
sauropodomorph (Wyman 1855) have been described as having notably thin-walled
bones as well.
Cope, E. D. 1870. On the Megadactylus polyzelus of Hitchcock. American Journal
of Science (series 2) 49:390-392.
Wyman, J. 1855. Notice of fossil bones from the Red Sandstone of the
Connecticut River Valley.
American Journal of Science and Arts 20(60):394-397.
(both are on Google Books; search by article title)
---------- Original Message ----------
From: Augusto Haro <firstname.lastname@example.org>
Subject: Re: BANDS > PADS vs. PALS
Date: Sun, 14 Feb 2010 09:28:45 -0300
There is a section of a basal sauropodomorph femur of material
referred to "Thecodontosaurus" figured in Benton et al. 2000 ("Anatomy
of Thecodontosaurus", in JVP) which seems to present very thin walls.
2010/2/14 Michael Mortimer <email@example.com>:
> David Peters wrote-
>> Bennett (1996) did this. He noted that most of the synapomorphies between
>> pterosaurs and Scleromochlus resided in the hind limbs, with little else to
>> promote a relatioship. So he tested the removal of the hind limbs to see
>> where pterosaurs might end up. I think it was a good test. It demonstrated
>> that the position of pterosaurs within the Ornithodira was based on flimsy
>> evidence. It's never a good fit when one is forced to say things like:
>> "Pterosaurs appear suddenly in the fossil record." Adding fenestrasaurs to
>> the Bennett (1996) taxon list showed that this previously untested clade had
>> more pterosaur synapomorphies. That data has never been tested, only
>> dismissed (by Hone and Benton 2008).
> While I agree the protorosaur hypothesis was not usefully tested by Benton
> and Hone, saying that a relationship is based on flimsy evidence if it is no
> longer recovered when hindlimb characters are excluded seems baseless. Which
> studies have been done eliminating hindlimb characters from other analyses
> and comparing the results? Most oviraptorosaurian characters are in the
> skull, but does that mean they're a poorly supported clade?
>> Agreed. That's why you should look very carefully at the ornithodires and
>> try to see if you can find an elongated fifth toe. If you can't find one
>> among them, and you won't, it's time to look to other taxa. Also look for
>> digit IV longer than III. That's the primitive condition in pterosaurs.
> You and your key characters. By that reasoning, we'd exclude
> therizinosaurids from Theropoda and sauropods from Dinosauromorpha.
>> Perhaps it does count for something. The skeleton of Sharovipteryx was
>> hollow. That's a start. Be interesting to see how far back air sacs go in
>> pterosaurs. Not sure that's been determined yet. Are they known in Triassic
> Hollow bones are often unrelated to pneumaticity, though the latter can cause
> the former. Basically every theropod has hollow limb bones, but almost no
> Mesozoic theropod has pneumatized limb bones. Bone wall thickness is
> something that desperately needs examination in more taxa. The old canard
> about only theropods (and pterosaurs) having hollow bones is certainly false.
> Mickey Mortimer