Comments on: Tyrannosaurus Rex: Armed and Dangerous

By: Blog Carnival, Edition #4: Texas Troubles, Big Dinosaurs, and a Danny McBride Interview | Dinosaur Tracking

Thu, 29 Jan 2009 16:42:41 +0000

[...] Small: As we’ve noted before, the mighty T. rex had arms that were so small that some early theorists even suggested they were [...]

By: Dinosaur Tracking

Dinosaur Tracking — Tue, 28 Oct 2008 14:16:55 +0000

[...] that’s all about candy, petty vandalism and dress-up. Ever want to tyrannize the world like a T. rex? Lumber around gulping party snacks like an Apatosaurus? Stain the carpet like a coprolite? This is [...]

By: Linda N ewman

Linda N ewman — Sat, 18 Oct 2008 15:30:56 +0000

Birds, which are descended from dinosaurs, turned their arms into wings. Wing muscles are powerful, but not well adapted to grasping. T-reges probably were too large to fly, but just like birds, they didn’t need more than two feet. The small arms were probably useful for clutching in certain situations; every extremity in every animal does not have to be useful in combat.

By: Berney Lincoln

Berney Lincoln — Fri, 17 Oct 2008 19:42:26 +0000

Isn’t it possible that T Rex’s arms are smaller due to evolution? If they weren’t used or if they were a problem than over the thousands of years that they roamed nature may have shortened the arms similar to what humans experience in their little toes? Supposedly in a few more hundred years we won’t have them at all. If it is possible that the arms were getting smaller and we have only uneartherd the most recent of the T Rex’s then it might be possible that at one time the arms were longer but not used enough to maintain their length.
With that said, I am also realizing that I can’t think of one carnivorous dino that did have proportionally large arms. Some of the smaller ones did but even they weren’t truly proportionate to the body size. Nothing like a human or ape arm. The reptiles of today all seem to have similar arm and legs. by that I mean they front and back legs are about the same size. We don’t have many reptiles that stand on two legs and have short arms. We do have a few lizards that run on rear legs but the front ones are the same size. Kind of strange.

By: K. Kederich

K. Kederich — Fri, 17 Oct 2008 02:59:11 +0000

Actually, the small limb size solves itself exactly because of weight issues. Imagine, with arms ANYTHING LESS than as massive as the T-Rex legs, trying to wrestle with prey of a smiliar size. Any arms much smaller than Rex’s legs would literally be torn off! And, massive arms simply weigh too much, and require vast skeletal structures to support. So, for safety, Rex’s arms dwindled into little things that were not in the way and could not be hazards to his own health. I suspect they were proportionately larger in the very young, and little Rex’s would have lower mass and be less likely to tear themselves limb-from-body. As for adults,, nature always finds something to do with limbs. Conducting orchestras, for example. Or, blogging.

By: wm schanz

wm schanz — Thu, 16 Oct 2008 22:59:29 +0000

The armes were obiviously used to move chess pieces! The tail and hide legs were much to clumsy.

By: Sean Craven

Sean Craven — Sat, 11 Oct 2008 12:28:04 +0000

The main problem in dealing with this question is that barring some really spectacular and unlikely fossil evidence all we’ve got is speculation.

One thing we do know is that Tyrannosaurus used its arms vigorously — there are a number of injuries recorded that demonstrate this pretty clearly.

Since all we’ve got is speculation, here’ my two bits. Arms three times as strong as mine aren’t going to be much use in dealing with animals who’s weight is measured in tons. This goes for both breeding and predation. I’m not saying the arms never came into play in these scenarios — I just doubt they were of much use.

My guess (and since it’s not testable don’t think it’s anything more than a guess) is that they may have been used for nest building. Holding down a struggling Edmontosaurus seems unlikely. Gathering and carrying branches makes more sense to me.