Re: About dinosaurs and feathers.

[Daniel Bensen <dbensen@gotnet.net>]

>>So I was wondering if someone could tell me something
about the current theories about the evolution of feathers and about the
feathers on Sinosauropteryx and Caudipteryx.<<
Whooph!  Now _there_'s a topic that can keep us going for a while.
Well, the current theory is that some (if not all) dinosaurs had feathers.
Some people believe that feathers (or at least, hair or bristle-like feathery
integument) are a basic trait of _all_ dinosaurs, and that some lost feathers
in favor of scales as they grew in size (just like elephants don't have
hair).  Others believe that _no_ dinosaurs had feathers and that recently
found dinosaur fossils with feathers were either flightless birds
(Caudipteryx) or were real dinosaurs, but the feathers were artifacts of
preservation.  My view (and I think, the view of most paleontologists) is
somewhere in between the two extremes.  The generally excepted theory is that
the evolution of feathers (by "feathers" I mean bristly "dinofuzz", not
flight feathers) occurred somewhere within Coelurosauria, including the
compsognathids (defiantly), the tyrannosaurs and ornithomimes (maybe), the
oviraptors and therizinosaurs (almost defiantly, although no fossils to prove
one way or the other have been found to my knowledge), the deinonychosaurs
(defiantly), and Avialae.
As to _why_ dinosaurs evolved feathers, all the list has been able to
generate are just-so stories without any fossils to back them up either way.
My favorite just-so story is that (possibly arboreal) coelurosaurs evolved
dinofuzz for insulation and then widened some bits of fuzz into plates to act
as visual displays.  Coincidentally, these plates were also useful to control
dives from trees (and swimming, too) and so the plates started to be selected
for aerodynamics as well as display (It is equally plausible that the plates
were _first_ used for gliding and _then_ for display, although I rather like
the idea of frivolity finding a good use).
Be sure to take what I say with a pinch of salt.  I'm sure many honored
people on the list would disagree with some part (or all) of the information
above.  They could be right.

Dan

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