T.rex Arm Usage

I personaly feel that they were used for nothing, here's why. 

As the tyrannosaurs evolved you could see that gradually their arms were geting smaller, and their heads were geting bigger, I believe that if they kept evolving, that they would be gone.

Possible. After all, I listed it, haha

Nice list! I think it would be kind of funnt to see a Tyrannosaurus with a gaint head and no arms.

It's called an abelisaur, lol, JK.

Thanks Sci-Fi

Yeah, it probably wouldn't completely loose its arms but thet probably would be simliar to most of the Abelisaurids arms. :)

Personally, I think they where vestigial.

Maybe, maybe not :)

Mabye the babies had some use of it like catching flies but as they got older they didn't use it as much, lol!

That's possible. Maybe they did use them more as juveniles.

id say 4, or what LXLPLICTZ said

Like I said, possibly. Hard to say without a living T.rex

It's a possibilty that it could use them whenever it needed to. I think it used them during mating and when standing up. 

Yeah, maybe.

Perversely, these arms were not long enough to reach the mouth, and yet, evidence shows that they were heavily muscularized and were in regular use, clearly discounting any suggestion that they might be useless and vestigial.

as tempting as it may seem, any speculation about the function of the arms is not strictly necessary in a discussion about why they are so small. To do so would be to imply that T. rex’s arms were tiny because they were selected to be tiny. It would assume that, had T. rex needed long arms, it could have had them. Which contradicts the train of evolution that had ultimately lead to Tyrannosaurus.

r. Instead of thinking about it in terms of why they we so small, some have thought about the problem in terms of, why couldn’t they be larger? In other words, perhaps long dangerous forearms would have been very useful for T. rex; it’s just that it couldn’t have them because of constraints in evolution.

This concept of constraints in evolution is well understood but often overlooked. It’s easy to forget that evolution is not a free-for-all. Just because a structure would be particularly useful for an organism does not mean that it can be evolved. Instead, its evolution is strongly dictated by two main factors: firstly, constraints from its ancestor’s body plan, which form the blueprints as raw material for evolution, and secondly, constraints from development. Thirdly, and the most overlooked fact in the idea of why tyrannosaurs had disproportionately small arms, is the ecological niche the occupied.

My hypothesis is that as the skulls of the Tyrannosaurids grew larger, the teeth blunter, the arms began to shrink. Why? to counterbalance the weight of the animal. Long arms coupled with an enlarged skull would have made the animal far too front heavy. The arms were certainly not vestigial though, and most likely aided in interspecies copulation, and helping the animal get to its feet after resting.

I agree with Carnosaur on this one, though I think it would be difficult for a Tyrannosaurus to use its arms to push itself off the ground expecially considering its hands were naturally facing the wrong postion to allow for the best leverage and while it is possible the wrist could rotate, like evidence from another theropod suggests, it seems an unesssesary strain on the animal. Plus large flightless birds seem to have no difficulty getting up of the ground with no help form their wings so the arms helping a Tyrannosaurus to get up doesn't quite fit for me. Other then that I fully agree.

Both very good points. This discussion is going well.

No offense Rex Fan, but 450 lbs my butt. The only thing I see them being used for is mating (gripping, tickling even) and maybe put a scratch on a dinosaur (that is, if it got close enough). 15 in teeth, don't think that's right, maybe 11-12 in and 4.5 ft jaws.

http://www.unearthingtrex.com/pages/rex_traits.html

Scroll down a bit. You'll read all about the 400 some pound lifting.

The longest T.rex tooth on record is 15 5/8 inches around the curve

(cast of real fossil)

And yes, T.rex skulls are 5 ft(so I guess you could technically say the jaws themselves were 4-4.5 ft).