The Cleveland-Lloyd Dinosaur Quarry is the densest collection of Jurassic dinosaur fossils. Since its discovery in the 1920s, numerous hypotheses have been proposed to explain the origin of the quarry. Were the dinosaurs poisoned? Did they die due to drought? Were they trapped in quick sand? A new study suggests that the quarry represents numerous mortality events which brought the dinosaurs to the site over time, rather than a single fatal event.