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Re: Vestigial Arms (was: Theropod limbs - how mobile?)



On Sunday, May 19, 2002, at 01:50  AM, David Marjanovic wrote:

"Maximum working range" = 199 kg for the biceps alone.

Haven't we got to be a little skeptical of such estimates? I wasn't aware that muscle strengths could be estimated with any degree of precision.


Even if they were that strong, they would still be ripped off by a struggling six tonne animal. I cannot envision tyrannosaurids struggling with their prey, it seems to risky for such large animals. To get their hand claws lodged in their prey would require tyrannosaurids to get very close, with wide areas of contact with their prey. At such close quarters, a simple shift in weight from the herbivore would throw the tyrannosaurid off balance, because its movement would be severely restricted. Falling over next to a panicked Triceratops or Anatotitan would be disastrous!

And if they were using their arms for such purposes, why were they so short?

It has been suggested before (sorry, I can't remember who it was) that they used their arms for intraspecific contests. The arms were small to keep them out of the way, and save energy growing them, yet they remained muscular for arm-wrestling with rivals.

You know it makes sense. ;-)

P.S. Show me a convincing drawing showing a tyrannosaurid using its arms to subdue prey, and I will reconsider.

John Conway, Palaeoartist

"All art is quite useless." - Oscar Wilde

Protosite: http://homepage.mac.com/john_conway/
Systematic ramblings: http://homepage.mac.com/john_conway/phylogenetic/