Austrosaurus

Abstract: New observations on various sauropod postcranial elements from Queensland provide insights into the taxonomic composition of northern Australia's sauropod fauna and the structure of sauropod vertebrae. An incomplete sauropod humerus from a site near Blackall, Queensland, represents the southernmost occurrence of sauropod fossils in the Eromanga Basin, and indicates a possibly new taxon. The internal architecture of at least one of the vertebral centra of Austrosaurus mckillopi comprises bony disks parallel to the posterior articular face and bony lamellae perpendicular to the anterior articular face reinforcing the structure against axial forces. The lack of pneumaticity proximally in dorsal ribs indicates that A. mckillopi may not be a titanosauriform. Material (QM F6737) from the Winton Formation includes probable osteoderms, the first known from Australian sauropods, and some of the oldest known. Comparison of this specimen with named Winton Formation sauropods suggests that it represents a distinct taxon.

Abstract: Cretaceous (Albian–Cenomanian) sauropod body fossils are known from the Eromanga Basin of central Queensland and Surat Basin of northern New South Wales/southeastern Queensland. Most bones are uncrushed and undistorted. Associated components of the caudal and forelimb skeleton are dominant in current collections and probably derived from more complete skeletons now lost to erosion, or yet to be exposed. Dorsal and cervical vertebrae have rarely been reported and no cranial material has yet been found. None of the Australian sauropod remains shows evidence of predation or scavenging, but at least two specimens of Wintonotitan wattsi were intimately associated with plant macrofossils allowing limited inference of their postmortem environments.

Abstract: The Cretaceous sauropod material from Queensland, Australia, has been regarded as pertaining to a persistently primitive sauropod lineage ( e.g. , Coombs and Molnar). The specimens derive from the Toolebuc and Allaru (Albian marine) and Winton (Cenomanian continental) Formations. Recent phylogenetic analyses carried out by workers in Argentina, the USA and England permit a reassessment of this fragmentary material. As far as can be ascertained from the material, there is no indication from the character states that more than a single taxon is represented. Character states diagnostic of the Titanosauriforrnes, the Titanosauria, the Somphospondyli and the Titanosauridae are present. Thus the Queensland material does not pertain to cetiosaurids but belongs to titanosaurs, extending their range into Australia. KEY WORDS. Sauropods. Austrosaurus. Titanosaurs. Cretaceous. Paleozoogeography.

Abstract: Sauropods are the best represented dinosaurs in the Cretaceous formations of the Great Artesian Basin of northeastern Australia. Three species have been named: Austrosaurus mckillopi from the Allaru Mudstone; and Diamantinasaurus matildae and Wintonotitan wattsi from the Winton Formation. The total number of sauropod specimens known, however, greatly exceeds this number and previous studies have not been in a position to portray the true diversity of the fauna. As such, a full reassessment of the Cretaceous sauropods of Queensland is underway. A sauropod fore limb excavated from the Toolebuc Formation in the mid-1990s has been determined to represent a new genus and species of titanosauriform, characterized by having a dorsoventrally elongate coracoid and a distal posterior expansion on its radius. The slightly younger Austrosaurus is currently being reassessed. More material from the holotype site was discovered in the 1930s after its original publication by Longman, and this will be fully described for the first time. Wintonotitan and Diamantinasaurus are both under reassessment, and new remains pertaining to the holotype individual of Diamantinasaurus are in the process of being described. Wintonotitan is resolved as a basal somphospondylan and Diamantinasaurus as a primitive lithostrotian, similar to the previous interpretations made by Hocknull et al. (2009). Recent excavations in the Winton Formation have resulted in numerous discoveries, among them a 50% complete, semi-articulated postcranial skeleton pertaining to a new species of titanosauriform with extremely wide-hips and several unique features of the manus. The vertebrae of this species are somewhat similar to those of Diamantinasaurus suggesting a close relationship and possibly representing a local lithostrotian radiation. It is hoped that this research will greatly increase our knowledge of Australia’s sauropod fauna and allow us to make hypotheses about sauropod dispersal and response to palaeoclimatic change following on from the revision of their phylogenetic positions.