Low down on the famous quarry wall of Dinosaur National Monument, there’s an unusual bone.
It’s not the shape of the bone, or even that species, that makes it odd. It’s the postmortem fate of the Jurassic antique that makes it stand out. You can even see the clues from the gallery floor. The femur, just one of many in the immense osteological logjam and cataloged as DINO 5119, is marked by multiple grooves running almost perpendicular to the bone’s orientation, as well as smaller scratches running in a different direction – bite marks. In over 1,500 vertebrate remains found at the quarry, this slightly-masticated bone is the only one of its kind.
But who bit the bone? Given the size of the grooves running across the thigh bone, there are at least three contenders. The bones of Allosaurus have been found in the same quarry, and this large predator was the most common carnivore of its time. The odds are with Allosaurus. But paleontologists have also turned up the bones of the tri-horned Ceratosaurus and the monstrous Torvosaurus from the same deposit. Allosaurus, Ceratosaurus, and Torvosaurus were the big three of their time, the apex predators of the fern-covered floodplains now preserved as the Morrison Formation across the west, and any of them could have made those grooves.