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Re: 11th specimen of Archaeopteryx



Tim Williams wrote:
>
> If _Archaeopteryx_, microraptorines etc were roosting in trees,
> there's simply no excuse for *not* having a hallux that was low enough
> and large enough to grip branches - ideally combined with at least
> some reversal of the hallux, for the pes to be capable of some kind of
> opposable grip.

Not to pounce on this one sentence, but I simply don't agree that this is
how evolution works. There are myriad cases where we might expect an
anatomical adaptation, where one would make sense, but we do not get one.
It is not true that there must be an "excuse".

just as one quick and pedestrian example, there is no "excuse" for mammals
to have external testis which descend into a scrotum seeking the lower
temperatures that provide more efficient spermatogenesis. Birds adapted to
endothermy and were able to keep their testis inside the abdomen, where
they are far less prone to injury.