Hamburg, Aug 25 (DPA) Forget the movie image of Tyrannosaurus rex engaged in battle with other brutes his own size. In fact, T-rex was a cowardly bully who preferred to pick on runts who were no match for him, according to a team of German scientists.

Fossil evidence collected by researchers led by Oliver Rauhut, palaeontologist at Ludwig Maximilians University in Munich, indicates that Tyrannosaurus tended to go after juvenile plant-eating weaklings who were far smaller and no match.

'Unlike their adult and well-armed relatives these young animals hardly posed any risk to the predators,' says Rauhut. 'And their tender bones would have added important minerals to a theropod's diet.'

In a news release announcing the surprise findings, he adds: 'Animals such as T-rex are often seen as the perfect 'killing machines' with extremely powerful bites, which were able to bring down even the largest possible prey. But the very few fossils that reflect the hunt of predatory dinosaurs on large herbivores tell a tale of failure -- the prey either got away, or both prey and predator were killed.