Colin Richard McHenry

PhD Thesis

University of Newcastle, Australia

PhD

637

The large pliosaur Kronosaurus queenslandicus is known from numerous specimens from the Early Cretaceous marine sediments of the Australian Great Artesian Basin. The preservation of these specimens in nodular limestone generally lacks pronounced taphonomic distortion, allowing the three-dimensional shape of the osteology, in particular the skull, to be inferred with confidence. Three-dimensional geometry is critical data for the functional analyses that can form the basis for reconstruction of palaeoecology, in particular, approaches based in computational biomechanics that make use of high resolution Finite Element Modelling. These techniques have been used successfully to infer diet and feeding behaviour in various species of extinct carnivore, and are here applied to a species of large pliosaur for the first time. The cranial anatomy of Kronosaurus queenslandicus is here summarised for the first time, and outstanding questions concerning the taxonomy of the relevant material are addressed as fully as possible given available data. Overall body proportions and size are estimated in the context of other known material from specimens of large pliosaurs. The material examined supports the hypothesis that there is one species of large pliosaur in the Late Albian the Great Artesian Basin, and this material is referred to Kronosaurus queenslandicus Longman 1924. Material from the Late Aptian of the Great Artesian Basin is also Kronosaurus, and is presently referred to Kronosaurus queenslandicus Longman 1924: however questions about the anatomy of Kronosaurus boyacensis Hampe 1992 mean that further examination of material to hand, or recovery of new specimens from the Late Aptian, may require the taxonomic status of the Late Aptian material to be reviewed. Kronosaurus is a member of the Brachaucheniidae Williston 1925. Maximum size is 10.5 metres total length and approximately ~11,000 kg body mass. Biomechanical analysis of the skull of Kronosaurus shows that it had a high bite force, comparable to that predicted for a hypothetical similar sized saltwater crocodile Crocodylus porosus. The magnitude of its maximum bite force, around 30,000 Newtons, was likely exceeded by Tyrannosaurus rex and Carcharocles megalodon. Finite element modelling of the skull, compared with the skull of a 3.1 metre Crocodylus porosus, suggests that the skull of Kronosaurus carri

English