Nanotyrannus lancensis — long thought by many to be a teenage Tyrannosaurus rex — was in fact a fully mature, distinct species of smaller tyrannosaurid, according to a team of U.S. paleontologists who analyzed the ceratobranchial (hyoid bone) of Nanotyrannus lancensis and revealed a record of development. A Late Cretaceous face-off between an adult Nanotyrannus lancensis (left) and two juvenile Tyrannosaurus rex, with a sub-adult Tyrannosaurus...
