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RE: 11th specimen of Archaeopteryx
The pdII-3u (second pedal ungual) of *Archaeopteryx lithographica* (using the
London specimen, NHMUK R37001, image here:
) is no more recurved than the third (pdIII-4u). In the given specimen, it is
just as recurved. While the condyles of the first phalanx (pdII-1) are slightly
expanded dorsally, this doesn't change the morphology of the second phalanx
(pdII-2), stressing that while the foot might have had some higher form of
extensibility than the third toe, the ungual is no more, but might be less
"sickle-like" than the third (or fourth) unguals. Incidentally, the specimen
shows a "reverse" hallux as an artifact, with MTI actually separated from MTII.
So while the primary data used to infer a "sickle claw" holds true (in
regards to Paul's original thesis), this is based in truth solely under the
slight expansion joint between pdII-1 and pdII-2. The ungual, unlike "raised
claw"ed dromaeosaurids such as *Microraptor zhaoianus* or *Deinonychus
antirrhopus,* is about as large as the third ungual, and the claw is no more
recurved than the others. This implies the ungual likely interacted with the
substrate along with the other claws. Thus, "sickle clawed," albeit subjective,
is inapplicable in either sense. Or so my premise holds.
Jaime A. Headden
The Bite Stuff (site v2)
"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion
> Date: Wed, 2 Nov 2011 10:38:11 -0400
> From: email@example.com
> To: firstname.lastname@example.org
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> Subject: Re: 11th specimen of Archaeopteryx
> Another difference between Archaeopteryx (and Microraptor) and all modern
> birds, one which makes their pedal morphology hard to compare directly, is
> that the former had that sickle claw on the specialized second toe.
> I know that a few authors have suggested that the claw could have functioned
> in climbing.
> What do people think about the possibility that this could grasp branches,
> perhaps serving as a sort of analog of a hallux?