Abstract
Australian dinosaurs have played a rare but controversial role in the debate surrounding the effect of Gondwanan break-up on Cretaceous dinosaur distribution. Major spatiotemporal gaps in the Gondwanan Cretaceous fossil record, coupled with taxon incompleteness, have hindered research on this effect, especially in Australia. Here we report on two new sauropod specimens from the early Late Cretaceous of Queensland, Australia, that have important implications for Cretaceous dinosaur palaeobiogeography. Savannasaurus elliottorum gen. et sp. nov. comprises one of the most complete Cretaceous sauropod skeletons ever found in Australia, whereas a new specimen of Diamantinasaurus matildae includes the first ever cranial remains of an Australian sauropod. The results of a new phylogenetic analysis, in which both Savannasaurus and Diamantinasaurus are recovered within Titanosauria, were used as the basis for a quantitative palaeobiogeographical analysis of macronarian sauropods. Titanosaurs achieved a worldwide distribution by at least 125 million years ago, suggesting that mid-Cretaceous Australian sauropods represent remnants of clades which were widespread during the Early Cretaceous. These lineages would have entered Australasia via dispersal from South America, presumably across Antarctica. High latitude sauropod dispersal might have been facilitated by Albian–Turonian warming that lifted a palaeoclimatic dispersal barrier between Antarctica and South America.
Highlights
The effect of the break-up of the Gondwanan supercontinent on the distribution of terrestrial animals during the Cretaceous remains the subject of heated debate[1], despite marked improvements in the quality of palaeogeographic models[2]
The only ways to improve assessments of Cretaceous Gondwanan dinosaur palaeobiogeography are to amplify the Gondwanan Cretaceous fossil record, and to utilise more rigorous analytical tools to assess the limited data at hand
Briefly describe, two new sauropod dinosaur specimens from the Cenomanian–lower Turonian Winton Formation of Queensland, northeast Australia (Figs 1 and 2). The first of these specimens forms the basis for Savannasaurus elliottorum gen. et sp. nov., and comprises one of the most complete sauropod skeletons ever found in Australia
Summary
The effect of the break-up of the Gondwanan supercontinent on the distribution of terrestrial animals during the Cretaceous remains the subject of heated debate[1], despite marked improvements in the quality of palaeogeographic models[2]. On the basis of palaeogeographic reconstructions alone, dinosaurs from the mid-Cretaceous of Australia would be expected to be most similar to those from South America and Antarctica This is because these three continents (along with Zealandia) formed a single contiguous landmass for the majority of the Cretaceous[2]. Briefly describe, two new sauropod dinosaur specimens from the Cenomanian–lower Turonian (lower Upper Cretaceous) Winton Formation of Queensland, northeast Australia (Figs 1 and 2) The first of these specimens forms the basis for Savannasaurus elliottorum gen. The other specimen is referred to Diamantinasaurus matildae[20,22] and includes the first partial sauropod skull identified from the Australian continent[25] These new data are utilised to provide a revised view of Cretaceous Gondwanan sauropod dinosaur palaeobiogeography
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