During the Jurassic, the quarry was a mudhole where several enormous sauropods got stuck and apparently caused a feeding frenzy that lured and trapped many carnivorous dinosaurs. Most of the allosaurs are from this site, as well as the unique Stokesosaurus and Marshosaurus. Dinosaur National Monument, Utah: First excavated by Earl Douglas working for the Carnegie Museum in 1909 with the purpose of finding sauropods from the Morrison Formation for public display.