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Re: polarity of bipedality in dinosaurs (real long--TOO long)



In a message dated 96-09-26 17:33:00 EDT, ajhowey@ix.netcom.com (Andrew
Howey) writes:

>Please forgive me if I'm mistaken, but if the skeletal features of
>_Archaeopteryx_ and _Compsognathus_ were similar enough that at least one
>specimen of _Archaeopteryx_ was mistaken for _Compsognathus_ for so long
>after its discovery, is it not possible that they might have had other,
>external similarities (ie. feathers)? 

Indeed it is eminently possible. So--why don't they show up in either of the
two otherwise virtually complete specimens of _Compsognathus_? As you note,
they could have washed away after falling out, but then we have to account
for why the little carcasses themselves were otherwise so undisturbed. After
all, the feathers didn't wash away in _Archaeopteryx_ (except in those
specimens that are practically dismembered), and the taphonomy of the
_Compsognathus_ specimens is quite similar.

Feathers of flightless birds tend to become small and hairlike after a period
of evolution into cursoriality. Perhaps this tendency also accounts for the
lack of preserved feathers in theropod dinosaurs, among which, if they were
indeed avian ancestors, one might expect to find them. That is, feathers may
have been secondarily vestigialized or lost in theropods.