The dinosaur bones now exposed on the Quarry cliff were buried in an ancient river about 150 million years ago. Over time the sediments turned to rock, protecting the bones in a stone time capsule. This photo shows a "bone jam," made up of the fossilized bones of large sauropods. Huge leg and shoulder bones of sauropods such as Apatosaurus and Diplodocus dominate this section of the quarry face.
Photo and caption courtesy of NPS.gov
