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Re: Archaeopteryx Pes



Nick Longrich wrote-

> Actually, Jacques Gauthier was the first to propose a
> hyperextensible digit II in Archaeopteryx (in his 1986 theropod
> phylogeny paper) and observation of the Eichstatt specimen (or casts
> like the ones I've seen) makes it pretty clear he's right: the end of
> the first phalanx in digit II has a distinctly enlarged articular
> surface that would have allowed the toe to retract. It is much larger
> than the other joints, and like the rest of the skeleton the toes are
> very well-articulated, as far as I can tell.

Unfortunately, I don't have a copy of Elzanowski and Pasko's paper on hand.
If I remember correctly they determined phalanx II-1 of the Eichstatt
specimen was preserved upside down, so that what appears to be the dorsal
surface is actually the ventral.  Thus, the distal articulation is expanded
ventrally and would not have been able to retract the rest of the digit.
Other phalanges are also preserved at different angles, like IV-2 which has
its ventral side up.  I'll check the article tomorrow and correct my
statements if I got any details wrong.

> Something very similar seems to have been going on in Confuciusornis,
> Sereno I think was the first to note that.

Chiappe et al. (1999) deny predatory specializations in the pes of
Confuciusornis and the distal articulation of phalanx II-1 doesn't look
dorsoventrally expanded in specimen GMV-2130 at least.  I could be wrong
however, as it is shown in dorsomedial view.

Mickey Mortimer