A dinosaur skull on display in Montana still has a Tyrannosaurus rex tooth jammed into its face, frozen in place for 66 million years. The fossil, an Edmontosaurus skull with a broken tyrannosaur tooth lodged in its nose, offers scientists one of the clearest windows yet into how the iconic predator attacked its prey. The specimen is now the subject of a new study published in the journal PeerJ.
A tooth that names both victim and attacker
The nearly complete Edmontosaurus skull was unearthed in 2005 from the Hell Creek Formation in eastern Montana, on land managed by the Bureau of Land Management. It now resides in the Museum of the Rockies at Montana State University, where it sits in the Hall of Horns and Teeth. Researchers from Montana State University and the University of Alberta in Canada teamed up to study the fossil. University of Alberta doctoral student Taia Wyenberg-Henzler and Museum of the Rockies Curator of Paleontology John Scannella led the investigation. They compared the embedded tooth with every known meat-eating dinosaur from the same rock formation. The match pointed squarely to Tyrannosaurus. Wyenberg-Henzler said that while bite marks on bones are common, finding an actual tooth still stuck in a skull is extremely rare. It lets researchers identify both the bitten animal and the biter.
CT scans reveal a face-to-face encounter
To understand how the tooth got stuck, the team used CT scans at Advanced Medical Imaging at Bozeman Health Deaconess Hospital. The scans showed the tooth's position in the Edmontosaurus nose, suggesting the two animals met head-on. Wyenberg-Henzler said the tooth placement indicates the Edmontosaurus faced its attacker directly, something that typically happens to an animal killed by a predator. The skull shows no signs of healing around the tooth, meaning the Edmontosaurus may have already been dead when bitten, or it died because of the bite. Scannella said the fossil captures a behavior: a tyrannosaur biting into a duckbill's face.
What this fossil means for understanding T. rex
Around 66 million years ago, near the end of the Age of Dinosaurs, Tyrannosaurus ruled what is now Montana alongside horned Triceratops and duck-billed Edmontosaurus. The embedded tooth gives researchers a rare direct record of a predator-prey interaction. Wyenberg-Henzler described the work as acting like Cretaceous crime scene investigators, piecing together what happened to this particular Edmontosaurus. The fossil is now displayed publicly at the Museum of the Rockies, where visitors can see the tooth still wedged in the ancient skull.
