Tyrannosaurus rex had terrible teenage tantrums that ended in fierce fights between bickering adolescents which left scars that can still be seen in fossils tens of millions of years old.
A study of one fossil, a young female T. rex called Jane, has revealed that she suffered the equivalent of a broken nose as a result of a savage bite from another adolescent T. rex, said Joe Peterson, of Northern Illinois University and the Burpee Museum of Natural History in Rockford.
"Jane has what we call a boxer's nose. Her snout bends slightly to the left. It was probably broken and healed back crooked. Only a few animals could have inflicted the wound," said Dr Peterson.
"When we looked at the jaw and teeth of Jane, we realised her bite would have produced a very close match to the injuries on her own face," he added.
"That leads us to believe she was attacked by a member of the same species that was about the same age. Because the wound had healed, we think this happened when Jane was possibly a few years younger."
The study is published in the journal Palaios.