The osteology of Diamantinasaurus matildae, the most complete Cretaceous sauropod described from Australia to
date, is comprehensively reassessed. The preparation of additional material from the type locality, pertaining to
the same individual as the holotype, sheds light on the morphology of the axial skeleton and provides additional
information on the appendicular skeleton. The new material comprises two dorsal vertebrae, an incomplete
sacrum (including four partial coalesced vertebrae), the right coracoid, the right radius, an additional manual
phalanx, and a previously missing portion of the right fibula. In this study we identify thirteen autapomorphic
characters of Diamantinasaurus, and an additional five characters that are locally autapomorphic within
Titanosauriformes. This work provided an opportunity to revisit the phylogenetic placement of Diamantinasaurus.
In two independent data matrices, Diamantinasaurus was recovered within Lithostrotia. One analysis resolved
Diamantinasaurus as the sister taxon to the approximately coeval Tapuiasaurus from Brazil, whereas the second
analysis recovered Diamantinasaurus as the sister taxon to Opisthocoelicaudia from the latest Cretaceous of
Mongolia. The characters supporting the recovered relationships are analysed, and the palaeobiogeographical implications
of the lithostrotian status of Diamantinasaurus are explored. A brief review of the body fossil record of
Australian Cretaceous terrestrial vertebrates suggests close ties to South America in particular, and to Gondwana
more generally.