Science Daily: Chicken-hearted Tyrants: Predatory Dinosaurs As Baby Killers.
Dr. Oliver Rauhut, paleontologist at Ludwig-Maximilians-Universität (LMU) in Munich, and his collegue Dr. David Hone surmise that giant carnivores like Tyrannosaurus preyed mainly on juvenile dinosaurs. "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. Now we hope for more fossils to be found that add new evidence to our hypothesis."
King of tyrants, Tyrannosaurus rex is by far the most famous dinosaur. Not even recent finds of slightly bigger – and maybe even more terrifying – species like Giganotosaurus could dent the aura of "T-Rex". But what would happen if the king turned out a baby killer instead of fearless hunter of much bigger prey? "Animals such as Tyrannosaurus are often seen as the perfect 'killing machines' with extremely powerful bites, which were able to bring down even the largest possible prey," says Rauhut of the Bayerische Staatssammlung für Paläontologie und Geologie and LMU Munich. "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, who is now at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China, therefore propose as a hypothesis 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 unexperienced young individuals," states 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."