Re: 11th specimen of Archaeopteryx

[Jason Brougham <jaseb@amnh.org>]

Fascinating.


On Nov 2, 2011, at 11:16 AM, Jaime Headden wrote:

> 
>   The pdII-3u (second pedal ungual) of *Archaeopteryx lithographica* (using 
> the London specimen, NHMUK R37001, image here: 
> http://www.nhm.ac.uk/resources-rx/images/archaeopteryx-lithographica-foot_71617_1.jpg
>  ) 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.
> 
> Cheers,
> 
>  Jaime A. Headden
>  The Bite Stuff (site v2)
>  http://qilong.wordpress.com/
> 
> "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 
> Backs)
> 
> 
> ----------------------------------------
>> Date: Wed, 2 Nov 2011 10:38:11 -0400
>> From: jaseb@amnh.org
>> To: skeletaldrawing@gmail.com
>> CC: tijawi@gmail.com; dinosaur@usc.edu
>> 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?
>> 
>> 
>                                         

Jason Brougham
Senior Principal Preparator
American Museum of Natural History
jaseb@amnh.org
(212) 496 3544