h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I would like to start a discussion on the question : Are dinosaurs (and I mean species like Tiranosaurus rex) hunters or scavengers? Or perhaps both? When looking at pictures of these animals and seeing these small forelimbs, I am inclined to think they were scavengers.But if they were hunting in packs it could be another story. By packs I would rather think of a family, consisting of a dominant male, a few females and one or two year old pups. (I have read dinosaurs growed rapidly, so there also must have been some kind of parental help when the eggs hatched.)
It is also possible these animals were both scavengers and hunters, depending on the size of the prey and/or the season.
Please lets start a debate about this as I understand the question has not yet been solved.

As a very strange reply about the small, useless forelimbs, consider footballers. During the whole game, they never use their arms (except for throwing the ball in from the sidelines), and so the arms aren't needed here.

Couldn't a tyrannosaur come down on its prey and use its incredible teeth as a potential third limb? Once the prey was pinned, the back legs could then be used to tear it to shreds.

What would be useful - although probably impossible to find out - is a tyrannosaur's gait, i.e. how big a step it took when it walked. A scavenger doesn't need to take big steps, since a carcas doesn't run. A hunter does need to take big steps in order to chase its prey.

Thank you, Robbish, for your contribution.
For a hunter not being able to use its forelimbs seems rather strange to me. I do not know if other exemples in nature. And even more unlikely seems to me ripping a prey apart with a hindleg while holding it with its teeth! Seems to me quite a feat for a biped !
For me the most likely explanation is : These big dinosaurs were scavangers and they COULD also hunted, but most probably in packs. What do you think ?

After all I think an animal does not necessarily needs arms to catch a prey. What about birds of prey? Yes, they fly and bounce on their prey, pinning it down with their talons. Next they use their beak. So, after all, a T.rex could very well catch a prey if fast enough, grab it with its huge muzzle filled with teeth and slaughter it.

Based on biomechanical studies, it was decided that a T. rex could run about 25 miles per hour. This is pretty fast, but doesn't really tell us about the T. rex's feeding.

It is interesting that you would bring up the stride of the T. rex because, while hunters should be able to run fast enough to catch their prey, scavengers need to be able to travel long distances.

Scavengers need to traverse large distances because carrion is not easy to come by. Vultures fly great distances to find their next meal.

Other things that point to the T. rex being a scavenger are its weak eye sight and very good sense of smell.

The T. Rex is one of the first animals known to possess binocular vision. Something most scavengers would not require.

Additionally, a couple million years ago, there was a large, flightless bird that was almost certainly carnivorous: http://en.wikipedia.org/wiki/Terror_Bird

That animal basically didn't even HAVE forelimbs, but it still managed to kill its food before it ate it, demonstrating that they aren't necessarily needed.

Personally, I think T. Rex probably did an equal share of both hunting and scavenging.