Re: Arms for a Carnotaurus

[Thomas_R_HOLTZ@umail.umd.edu (th81)]

>Speaking of Carnotaurus arms, I've only just got hold of a copy of the 
>description of this beast published by the LACM. In it the authors state 
>that the humerus had lost the torsion between the proximal and distal 
>ends, and that the radius and ulna did not cross as they do in other 
>theropods. This straightening out of the arm was supposed to have rotated 
>the orientation of the hand so that the palmar surface faced anteriorly! 
>(at least that was my understanding of their writing)This seems totally 

I had interpeted this as saying that the palms faced posteriorly, but either
way is weird indeed.

>bizare and I have great trouble imaging how it could work. In Stephen
>Czerkas's model it appears that the palms face medially like other 
>theropods. Has anyone actually seen the fossil or good casts? Which way 
>is the hand oriented? One other point is that the drawing of metacarpal 
>IV looks like a large Iguanodontid thumb-spike, yet it is not discussed 
>in the text. Could Carnotaurus have used its arms for offensive weapons? 
>(this might explain the increased range of movement at the shoulder joint)

Only as a REALLY close fighting weapon, since the total distance it could
stick out its arms was incredibly short.

One weird dinosaur!  And of course, since it is Aptian-Albian age, one
wonders if Late K abelisaurids had arms at all...

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661

"There are some who call me...  Tim."