Scientists have experimentally measured the bite force of adult T. rexes but not of younger tyrannosaurs. Fossils with juvenile bite marks, discovered by Joseph Peterson, have now allowed him and Jack Tseng to experimentally test how hard juveniles could chomp. Though their bite force is one-sixth that of an adult, it is still stronger than that of living hyenas. The measurement is higher than previous estimates, suggesting a different ecological niche for these youngsters.