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RE: 11th specimen of Archaeopteryx



Don Ohmes wrote:

<[A]re you saying that the foot of A. lithographica would have been unable to 
grasp your wrist?>

Yes, he is.

  All "Archie" specimens that show a reversed hallux, as of the Thermopolis 
specimen, show such a "morphology" due to a loose first metatarsal. It is not 
articulated. Articulation would, as some of the specimens show, that the 
phalanx is oriented closer to the "heterodactyl" orientation than it is to the 
"anisodactyl" orientation. Moreover, its position is too high and its length 
too short to enable actual grasping of anything: the pdI-1/pdI-2u articulation 
is not so close to the substrate on a static foot that the claw could have 
encompassed a branch it could stand on.

  Sadly, while widely cited and somewhat widely read, this mostly appears in 
Kevin Middleton's PhD thesis:

Middleton, K. M. 2003. Morphology, evolution, and function of the avian hallux. 
Ph.D. dissertation, Brown University, Providence, Rhode Island.

  This has been variously presented at symposia, which has helped disseminate 
the data, so the information is "known," even though its source remains 
relatively unpublished (for the purposes of U. S.-based availability). It also 
appears, although in somewhat muted form, in Middleton (2001), which is 
available here: 
http://www.brown.edu/Departments/EEB/EML/files/kevin_jmorph01.pdf . This work 
sets down the firm basis of inferring hallucial orientation by the morphology 
of MTI, which bears a "twist" on it as indicated by a ridge, or a J-shaped 
form, both of which are absent in *Archaeopteryx lithographica* specimens. 
This, coupled with MTI disarticulation in most "Archie" specimens, indicates 
one cannot say that "Archie" was capable of grasping _anything_ with its first 
toe.

  PS: I restate my objection to using largely unpublished information to 
support these hypostheses

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: Mon, 31 Oct 2011 23:24:17 -0400
> From: d_ohmes@yahoo.com
> To: dinosaur@usc.edu
> Subject: Re: 11th specimen of Archaeopteryx
>
> On 10/31/2011 10:50 PM, David Marjanovic wrote:
>
> > Still, their feet are better suited to this than Archie's or even
> > *Microraptor*'s.
>
> Wikipedia has an image of the "London Specimen" -- are you saying that
> the foot of A. lithographica would have been unable to grasp your wrist?
> Or walk on a horizontal branch the same diameter as your leg?