A Late Cretaceous “bone spike,” the thick layer of bones found in the fossil record around the time of a catastrophic extinction, has not been found until recently. A large bed of fossil fish bones from this time has been discovered on Seymour Island, Antarctica, covering more than 31 square miles (50 square kilometers). Although there is a possibility that the fish were killed off by volcanic activity, climate change, or some other environmental cause, their bones lie immediately above the iridium rich layer that marks the end of the Cretaceous period. In other words, it’s highly likely that the fish were victims of the catastrophic extinction that also affected the dinosaurs.