The big bite of the adolescent T. rex

UC Berkeley associate professor Jack Tseng explains his research on juvenile T. rex and what the findings tell us about the adolescent tyrannosaur's lifestyle.

Tseng loves bone-crushing animals - hyenas are his favourite - so when palaeontologist Joseph Peterson discovered fossilised dinosaur bones bearing the teeth marks of a young Tyrannosaurus rex, Tseng decided to try to replicate the bite marks and measure how much these kids could actually gnaw.

Last year, he and Peterson made a metal replica of a scimitar-shaped tooth from a 13-year-old T. rex juvie, mounted it on a mechanical test frame commonly used in engineering and materials science, and tried to break a cow leg bone with it.

Based on 17 successful attempts to match the depth and shape of the bite marks on the fossils - he had to do some testing because the fresh bone slipped too much - he determined that a juvenile could have exerted up to 5,641 newtons of force, somewhere between the jaw forces exerted by a hyena and a crocodile.

Compare that to the bite force of an adult T. rex - about 35,000 newtons - or the puny bite power of humans: 300 newtons.

Previous estimates of bite force for juvenile T. rexes - based on reconstruction of jaw muscles or a mathematical reduction of the bite force of adult T. rexes - were considerably lower, about 4,000 newtons. CONTINUE...