A fossil at Montana State University's Museum of the Rockies has given scientists a front-row seat to a Cretaceous-era murder scene, complete with the murder weapon still embedded in the victim. Researchers from Montana State University and the University of Alberta have published a study in PeerJ examining a nearly complete Edmontosaurus skull that still contains a broken Tyrannosaurus tooth lodged in its face.

The skull was unearthed in 2005 from the Hell Creek Formation in eastern Montana, on land managed by the Bureau of Land Management, and now resides in the museum's Hall of Horns and Teeth. University of Alberta doctoral student Taia Wyenberg-Henzler and Museum of the Rockies Curator of Paleontology John Scannella led the investigation, comparing the tooth to every known meat-eating dinosaur from the area. The match: Tyrannosaurus. CT scans at Bozeman Health Deaconess Hospital confirmed the tooth's trajectory.

"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," Scannella said, offering two equally grim possibilities. Wyenberg-Henzler added that the tooth's position suggests a face-to-face encounter, and the force needed to break the tooth off in bone points to "deadly force." Paleontologists have debated T. rex's hunting habits for decades, and this fossil provides a particularly pointed piece of evidence.