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Re: Pterosaur hair and Dino feathers



>My thoughts on this issue: With evidence of "feather scales" 
>(i.e. proto-feathers) on Longisquama, it seems likely to me that
>pterosaurs' fur and maniraptors/birds' feathers are derived from 
>"feather scales" in Lagosuchus or whatever the "Ur-endosauropsid"
>(Dinosaur-Pterosaur common ancestor) was.  No one knows exactly when
>true feathers emerged, of course, but with Archaeopteryx having feathers
>and birds now believed by some to be from another branch, it
>seems that all the maniraptors, and maybe all small theropods, had 
>feathers; and all small dinosaurs had at least the "feather-scale"
>insulation.
>
>                         -- Dave (expressing a humble opinion)

This message makes a number of assumptions that may not be correct:

a. that the peculiar scales of Longisquama are, in fact, proto-feathers;
b. that Lagosuchus (or whatever) also had such scales;
c. that Archaeopteryx is convergent to, not in the same clade as, true birds.

The latter, particularly, would hardly seem to be the general view (pace
Chatterjee and a few others).

I have yet to see any convincing evidence (and I admit I do not keep up with
the primary literature) that ANY archosaurian other than Archaeopteryx and
"true" birds had feathers.  This is not to say that they didn't - after all,
few genuine bird fossils show feather imprints - but so far I submit that
the most parsimonious hypothesis is that feathers are a shared derived
character of Archaeopteryx and birds ONLY (whether you choose to call
Archaeopteryx a bird or not).  Giving other maniraptorians, dinos or
archosaurians feathers is fun to do and may even be correct (at least for
some), but before it can be accepted as good science it will have to be
based on solid evidence (and I have seen none suggesting that pterosaur
"hairs", whatever they are, are homologous to feathers other than the fact
that both hair and feathers can be insulating structures (which is hardly
evidence)).
--
Ronald I. Orenstein                           Phone: (905) 820-7886 (home)
International Wildlife Coalition              Fax/Modem: (905) 569-0116 (home)
Home: 1825 Shady Creek Court                  Messages: (416) 368-4661
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