T. REX, WHY THE SHORT ARMS?
So then, why the short arms?
I have actually done a little research on this subject. I did much more research than I care to, but much less than I should have.
Scientists seem to be acceptive and dismissive of the short arms. That is they accept that the arms were short and then think no more about it.
Here is a typical comment:
(W)e do not in fact know for sure whether meat-eating dinosaurs such as this were active hunters -- tracking down, attacking, and killing prey -- or scavengers, feeding on the carcasses of other dinosaurs. While its huge jaws and its strong legs would certainly be forceful hunting weapons, Tyrannosaurus rex's arms were too short to reach its mouth, and its hands had only two fingers instead of three, making it unable to grasp. The fossils discovered thus far offer some evidence about whether theropods were hunters or scavengers, but not enough to answer the question.
Proponents of the scavenger theory also note that the T-Rex's scrawny front arms seem inadequate to hold a victim during an attack (Others point out some creatures, like the great white shark, are successful predators even with no arms at all).
First of all, the hunter or scavenger argument is silly. You’ve heard about the 400 pound gorilla? Well this is a 60 ton tyrannosaurus rex. It ate whatever the hell was there to eat.
Note that it was warm-blooded. That means its engine was running all the time. It was not like a snake that could eat once every six months. It had to eat regularly like at least once ever few days. It couldn’t just follow a herd hoping something dropped dead.
But the scientists are wrong to merely accept that the beast had short arms. Those short arms were the result of millions of years of evolution. Those short arms were perfect for that creature. The question is: Why?
Just as the missing water on Mars helps to explain the evolution of the Earth, those short arms will help to explain the life of that dinosaur.
There are three things that, if improved, will result successful evolution. Those are:
Food. (The ability to find it and eat it.)
A scientist friend of mine recalled that some creatures use otherwise useless arms to hold a partner in place during sex. That’s a possibility but, I think not too probable. There is always the argument that, yes, short arms would work, but longer arms would work better. In evolution, that’s a trump card.
The first thing that occurred to me was that longer arms might drag on the ground when it tried to move very fast. But arms are easy to tuck in and something that big couldn’t move that fast anyway. A fall at even moderate speed would probably kill it.
Even being slow it was probably fast enough to keep up with herds of plant eaters. T-rex would have no problem killing a single herbivore. And the arms would hold the animal in place for the killing.
But we come back to the trump card. How do short arms help in a way that longer arms wouldn’t help more?
I think there is only one answer.
Why are snakes so successful with no arms and legs?
Because they can reach the places in which their prey lives and hides.
The major prey of T-rex must have been burrowers. Its short arms didn’t hinder it from going in a ways, under ground, after a meal.
That is probably the answer.