[adrian_b]

Perhaps other big carnivorous dinosaurs might have eaten small prey when given the opportunity, but for adult tyrannosaurids this seems less likely.

The adult tyrannosaurids had arms that were far too short to be able to catch small prey with them.

The heads of the adult tyrannosaurids were very big, so they must have had a large moment of inertia that would have made difficult to rotate the heads fast enough to be able to catch small prey on the ground below them.

Perhaps the best chance for an adult tyrannosaurid to catch small prey would have been to stomp on it (like many prey birds, e.g. the secretary birds, do today). Only then it could have easily taken the dead body in the mouth.

This stomping behavior would be a more plausible means for tyrannosaurs to catch humans in a movie, instead of their typical depictions when they catch easily the humans only because those are frozen by fear instead of taking evasive actions. (The tyrannosaurs could certainly move their feet many times faster than their heavy heads located at the end of long necks.)