[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: 11th specimen of Archaeopteryx‏



  Manning et al. say nothing about "perching." That paper noted that when used 
to penetrate a relatively persistent substrate (using flesh but also projecting 
to wood, and tested against flesh), the claw is useful for climbing and was not 
necessarily effective for "slashing." This is not entirely consistent with 
arboreality, although that is possible, because climbing birds do not use just 
one ungual for climbing, they use all forward-projecting unguals, and this is 
not evident in dromaeosaurids. In birds, while the unguals are graded largest 
to smallest moving from toe two through toe four, then toe one, the unguals 
even in raptorial birds are relatively similar in size (cassowaries are freaks 
with straight pdII-3u's, ignore them); in dromaeosaurids, the pdII-3u is often 
twice the length of any other ungual, a suspiciously bizarre distinction that 
enforces a functional difference, especially in the strong curvature relative 
to the other unguals. And recall, despite the huge!
 pdII-3u, the other pedal unguals are _terrestrially_ adapted, even in 
*Archaeopteryx lithographica*. Moreover, it is questionable how one arrives at 
a conclusion that the highly recurved, huge forward ungual is indicative of 
"perching" or arboreality to begin with, merely that climbing is _not_ excluded.

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, 7 Nov 2011 20:23:22 +0000
> From: ssselberg@hotmail.com
> To: dinosaur@usc.edu
> Subject: RE: 11th specimen of Archaeopteryx‏
>
>
>
>
>
>
>
>
>
>
> Sorry, I had a copy of the Manning study (Manning et al. (2006, "Dinosaur 
> killer claws or climbing crampons?")at home but had lost the title page...But 
> my question still stands: IF the sickle claw allowed the animal to perch, " 
> wouldn't that have made a reversed hallux redundant, and also allowed the 
> third and fourth toes to retain their more corsorial proportions?" This is 
> important because if, as is now being postulated, the ancestors of birds were 
> or were in the process of becoming herbivores, the sickle may have been lost. 
> This could tip the balance in favor of a reversed hallux and a more "bird 
> shaped" foot and eventually, the loss of clawed hands.
>
>
>
> In spite of the tone of the rest of my letter, my real interest wasn't 
> whether or not deinonychosaurs were arboreal. Personally I think that various 
> species exhibited a wide range of behaviors, of course. I'm more interested 
> in the deinonychosaur foot as a sort of all-purpose tool, good for but not 
> specialized in any one task. I mean, are a cat's retractable claws “for” 
> gripping prey, climbing, or fighting off predators and rivals( or burying 
> poop)? I do think however that too much importance has been placed on a 
> reversed hallux as evidence of whether or not an animal spent time in trees.
>
> Scott Selberg