Friday, 20 April 2007

Tyrannosaurus Forelimbs Revisited

Earlier in the week, I posted some theories regarding the function of T. rex’s diminutive arms. I just thought I would add some recent research before I closed the topic:

Matt Smith (Museum of the Rockies) and Ken Carpenter (Denver Museum of Natural History) began examining the wrist, hand and finger bones of the T. rex forelimb and used wax to hold the bone joints together. This led them to figure out that the forelimb's two claws have an unusual feature: unlike the opposable human thumb and forefinger combo, which can grasp objects, the two dinosaur claws face away from each other like the barbs of a fishing hook.

What does this mean? Perhaps these claws embedded themselves into the prey’s flesh and immobilized it while T. rex used his jaws to finish the job. .

Matt Smith says, "People had been looking at [forelimb] function based on proportionate size. I don't think that's appropriate."


Anonymous said...

It should be clear that the position and size of the forelimbs afforded them easy access to the nipple region. Therefore it should be clear that they were used for nipple stimulation. This was likely part of the courtship rituals of T-rex. It is also part of a more controversial theory that Tyrannosaurus had mammary glands.

Laelaps said...

I've been pondering this over the past few days as well and I think we need to ask the question "What about sex?" It might seem silly, but could the little arms of a T. rex be a way for the male to hold onto the female during courtship? It would be quite a balancing act, so maybe the arms (with little ability to move and acting like "hooks") helped the male stay on for long enough to complete the act. Many males of various species (from sharks to some big cats) bite the female to hold onto her during mating, and given that the T. rex's jaws would do much more damange, maybe the little arms served a stabilizing function during that time. A thicker layer of skin on the females, especially on the back, would seem to confrim this, but then again if we had skin then they'd still be alive and we would know the answer. Again, I'm probably wrong, but it seems like a decent use for those little arms.