Bones found in the U.S. indicate a large population of leaf-eating, egg-laying ceratopsians and sauropods may have lived on for another 500,000 years after all dinosaurs are meant to have gone extinct.
It’s not uncommon for bones from one period to be found in geological strata from another. That usually happens when water exhumes and redistributes the bones.
But Fassett said he doesn’t believe that happened in the San Juan Basin. As proof, he points to his discovery of 34 bones from a single hadrosaur: If they had been washed away from their original location, they would almost certainly have been separated, not found together.The San Juan Basin is a well-known repository for dinosaur bones. Paleontologists have been investigating the region at least since the beginning of the 20th century. But if Fassett is correct, the mystery is why this would be the place dinosaurs made their last stand.