In 2005, paleontologists found a nearly complete Edmontosaurus skull in the fossil-rich Hell Creek Formation in eastern Montana. Now on display at the museum, a reexamination of the skull revealed one striking detail: a Tyrannosaurus tooth stuck inside its face. “The great thing about an embedded tooth, particularly in a skull, is it gives you the identity of not only who was bitten but also who did the biting. “The skull shows no signs of healing around the tyrannosaur tooth, so it may have already been dead when it was bitten, or it may be dead because it was bitten.”The Tyrannosaurus tooth. The tooth found inside this Edmontosaurus skull gives another look into Tyrannosaurus behavior.