November 4, 2009
Humans youngsters often use their hands and arms to push and shove, but young Tyrannosaurus were obviously a bit different than us. It would take a lot of effort for two of the fighting dinosaurs to get close enough to scrabble at each other with their small arms, and so they employed a different tactic instead: they bit each other on the face. As reported in the journal Palaios, the controversial tyrannosaur skeleton known as “Jane” shows signs of just such an encounter.
For years scientists have debated whether Jane is a juvenile Tyrannosaurus or representative of a hypothetical smaller tyrannosaur genus, Nanotyrannus, but it is not the purpose of the present paper to resolve this issue. Instead paleontologists Joseph Peterson, Michael Henderson, Reed Scherer and Christopher Vittore document the presence of several puncture wounds in the bone around Jane’s snout that could only have been made by another young tyrannosaur. Like living crocodiles and alligators, tyrannosaurs may have bitten each other on the face during confrontations to establish social dominance, and the pattern of damage on Jane’s snout is more consistent with this kind of social interaction than with an attack with an intent to kill her or feed upon her. It was pretty harsh, but face-biting was a way for theropod dinosaurs to keep individuals in line.
Based upon the details of the punctures the two tyrannosaurs appear to have been facing each other when Jane was bitten. Unlike the fragment of Gorgosaurus jaw discussed here last month, Jane’s wounds show signs of healing, and unlike the Tyrannosaurus study suggesting that dinosaurs suffered from a bird disease, there is no indication of infection. She survived the attack and healed.
This does not mean that Jane was totally unaffected by the bite. Bone is a living tissue that is constantly being remodeled as an organism grows, and damage to bones at a young age can affect the way bones grow. As such the punctures in Jane’s skull caused her snout to bend a little to the left during growth. This would not have affected her ability to hunt or bite, but it would have given her a slightly asymmetrical appearance.
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