Cold Plumage

[Garrison Hilliard <garrison@efn.org>]

Regarding my "feathers" inquiry, I found this reply most interesting...

-
Hi Garrison -


On your dml posting:

>(I know this is tangential (but I think of interest in the
endo-exothermic
wars)... has any
exothermic animal ever had feathers?>

This is a very interesting question.  Unfortunately you have been and will
be told that Longisquama's plumes are irrelevant to the question, but
unfortunately by people who do not understand the basic principles of
science and knowledge that their area of interest is based on.  (I'm sorry
to say this includes most palaeontologists, professional or otherwise.)

Plumes, probably homologous to birds' feathers but often different (they
were after all early versions of, or differently adaptated kinds of these
early versions) were the central defining character of archosaurs (and
maybe
preceding lines too) but most archosaurs lost them.  The scales of crocs
and
the dorsal plates of tortoises are long-adapted versions, and the various
scutes, spineseg the things on the psittacosaur, and "fur" of dinosaurs
are,
as well as birds' feathers.

Primitive plumes, developed during the Permian, were used for gliding by
cold-blooded types, so they had to be folded up out of the way sometimes,
to
aid sunbathing,  Latter, these foldable plumes were probably used for
"part-time insulation", allowing the development from cold-bloodedness
towards warm-bloodedness,  Longisquama has small plumes on its body as
well
as big plumes on its back.  The body plumes seem suitable for insulation
in
a warmish blooded type, though Longi's skeleton doesn't seem to have any
conclusively warm-blooded features that I know of.

Megalancosaurus and Drepanosaurus had pluumes fo gliding too, and they
might
have been cold-blooded.


Cheers,

John V Jackson      jjackson@interalpha.co.uk

"So many professors . . . so little time . . ."

Dare you visit...
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