'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.'

On the other hand, the also extremely sparse cases of direct evidence for the diet of predatory dinosaurs - stomach contents and coprolites - show that juveniles or much smaller prey species were ingested and the latter were swallowed whole.

Rauhut and Hone, therefore, hypothesized that large predatory dinosaurs only as an exception attacked other large dinosaurs, but mainly fed on juveniles.

'Even modern predators prefer old and sick animals or inexperienced young individuals,' stated Hone. 'These are an easy prey to bring down and the risk of injury for the predator is much lower. This strategy was probably the same in dinosaurs.'