Re: Claw function in Deinonychus

[Michael Mortimer <mickey_mortimer111@msn.com>]

Jaime A. Headden wrote-

> <As total length is uncertain for all except a few complete dromaeosaur
> specimens, perhaps a comparison of ungual length to another element's 
> length
> would be less prone to error.>
>
>   While this is certainly true, as noted in the last posts by Mike Habib 
> and
> myself, there is a signal albeit a weak one, based on the specimens 
> involved
> in. The reason I used body length is that it may more accurately capture 
> mass
> estimation and thus applicable to the hypothesis of weight-bearing pursued 
> in
> the thread. The use of other elements must bear directly on this issue for
> utility, or apply in a way to demonstrate functional applications.

I figure total length estimates can be very biased by varying tail length 
(which wouldn't affect mass much).  For instance, Deinonychus and 
Microraptor both have tails about five times their femoral length, while 
NGMC 91 has one ~3.6 times its femoral length.
Mass estimates cube any linear errors made when calculating them, so are 
even more fickle.

> <Sinornithosaurus
>  holotype- ungual 35, phalanx 15, femur 148>
>
>   Which ungual was this again? As in my previous posts, one projects 
> certain
> inconsistencies when measuring incomplete elements.

The holotype pedal ungual II.  As detailed in Xu and Wang (2000), although 
the ungual's distal tip is missing, it can be seen via CAT scan, and thus 
its size is precisely known.

Mickey Mortimer