Kronosaurus queenslandicus, cretaceous period, Queensland, Australia. Kronosaurus was a pliosaur (short-necked plesiosaur) and largest of group. This skeleton, 42 ft long is most complete known, discovered in massive blocks of Cretaceous age limestone (135 million years old) in Queensland, Australia. Portions of skull, backbone, paddles had weathered away, but enough remained that missing pieces could be restored. Harvard Museum of Natural History, Cambridge, Massachusetts, June, 2007.