premise: The trove of fossils at Zhucheng, China, is probably the largest single deposit of dinosaur bones in the world. While the massive quarry has given rise to nine new species of dinosaurs, the event that killed the species is still a mystery. One researcher thinks a landslide ripped the dinosaurs apart and mixed up their bones; another suspects the animals were dead and decomposing when their skeletons were swept to this spot by a massive flood or mud flow. Discoveries in Liaoning and Xinjiang are also helping scientists unravel the evolution of modern-day birds, a lineage that one Chinese palaeontologist believes begins with dinosaurs. One of his most recent discoveries, the chicken-size Xiaotingia zhengi, is giving scientists cause to rethink the classification of the Archaeopteryx, long considered the oldest-known bird. The Xiaotingia zhengi, they argue, provides evidence that both species were, in fact, feathered dinosaurs, not full-fledged birds.
hypothesis: The two researchers agree that a natural catastrophe was involved in the appearance of dinosaur bones at Zhucheng.