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Re: Archaeopteryx Pes



Nick Longrich wrote-

> It's hard to see, since on one side the phalanx is partially
> obscured by another digit, but in *both feet* the condyle extends
> dorsally, not ventrally. Arguing for a 180 degree rotation in both,
> while leaving the rest of the foot largely undisturbed, really would
> stretch it.

I checked the Elzanowski and Pasko reference today and here's what they have
to say-
"In fact, the entire digit is dislocated and seems to be rotated upside
down.  As a result, the usual ventral convexity is turned dorsally and
mimics a similarity to Deinonychus.  In any case, there is no trace of this
feature in other specimens, some of which have better preserved feet."
On the other hand, Greg Paul has told me these claims are absolutely
incorrect.
Obviously, this needs some further examination.  The left second pedal
ungual of the Eichstatt specimen has its dorsal side up, so the entire digit
was not rotated upside down, contra Elzanowski and Pasko.  As for phalanges
II-I and II-2, these also seem to be correctly oriented to me.
Archaeopteryx pedal phalanges have concave ventral sides and straight to
convex dorsal sides.  Phalanges II-1 and II-2 also exhibit this trait, as
preserved, which suggests they are correctly oriented.  I can also confirm
that the distal articular surface of phalanx II-1 is the largest in the pes.
I conclude that Gauthier, Paul and Longrich are correct in their
interpretation of hyperextendability in the second pedal digit of the
Eichstatt Archaeopteryx specimen.  What about Elzanowski and Pasko's further
argument that other Archaeopteryx specimens lack this feature?
Unfortunately, I cannot answer this question.  I only have good figures of
the Eichstatt and Solnhofen specimens.  The latter has one incomplete pes
and the other preserved in ventral view, so it cannot be examined properly.
Elzanowski and Pasko cite the Berlin specimen as lacking the feature and
figure an illustration in one of Ostrom's works that clearly shows no marked
dorsal expansion in the distal articulation of phalanx II-1.  Was Ostrom
mistaken in his reconstruction of the pedal phalanges or is this actually a
difference between the specimens, perhaps supporting a separate genus or
species (Jurapteryx recurva) for the Eichstatt specimen as has been
suggested in the past?  If anyone has access to a figure of the Berlin or
other specimens, feel free to write and help resolve this mystery.

Mickey Mortimer