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Re: Gatesy et al.'s footprint paper (excerpts)



Phil:

You said: "All in all, I was quite intrigued by the team's
conclusions.  It seems
that researchers now need to rethink the whole issue of the evolution
of
the theropodan hallux with a bit more care.  When *did* the hallux
reverse?  Maybe it was in the trees after all.  Padian *still*
maintains
that Archaeopteryx was not much of a percher (in spite of possessing
a
fully reversed hallux), and that true perching came later  (to quote
Kevin from _Nature_:>

"For instance, in Archaeopteryx, which is the first known bird, the
first toe is fully opposable (that is, it faces the other digits on
the
same foot), and in later birds the claws enlarge for perching,
suggesting the start of true arboreality." - Kevin Padian."

>From what I've seen in photographs of Archaeopteryx, although it does
appear to have a reversed hallux, the location of this toe is located
closer to the ankle joint than that of modern perchers where the
hallux is close to or in line with the rest of foot.  I suspect that
is why Kevin Padian and others have been reluctant to grant
Archaeopteryx the powers of perching, because you'd really have to
rock the ankle quite a bit back to get the hallux close to a branch.

But, I'm no expert, so fire away.

Matt Bonnan
Dept. Biological Sciences
Northern Illinois University