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Second specimen of the Late Cretaceous sauropod dinosaur Diamantinasaurus matildae provides new anatomical information on skull and neck evolution in early titanosaurs and the biogeographic origins of Australian dinosaur faunas

Poropat, S; Kundrát, M; Mannion, P; Upchurch, P; Tischler, T; Elliott, D; (2021) Second specimen of the Late Cretaceous sauropod dinosaur Diamantinasaurus matildae provides new anatomical information on skull and neck evolution in early titanosaurs and the biogeographic origins of Australian dinosaur faunas. Zoological Journal of the Linnean Society , 192 (2) pp. 610-674. 10.1093/zoolinnean/zlaa173. Green open access

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Abstract

The titanosaurian sauropod dinosaur Diamantinasaurus matildae is represented by two individuals from the Cenomanian–lower Turonian ‘upper’ Winton Formation of central Queensland, north-eastern Australia. The type specimen has been described in detail, whereas the referred specimen, which includes several elements not present in the type series (partial skull, atlas, axis and postaxial cervical vertebrae), has only been described briefly. Herein, we provide a comprehensive description of this referred specimen, including a thorough assessment of the external and internal anatomy of the braincase, and identify several new autapomorphies of D. matildae. Via an expanded data matrix consisting of 125 taxa scored for 552 characters, we recover a close, well-supported relationship between Diamantinasaurus and its contemporary, Savannasaurus elliottorum. Unlike previous iterations of this data matrix, under a parsimony framework we consistently recover Diamantinasaurus and Savannasaurus as early-diverging members of Titanosauria using both equal weighting and extended implied weighting, with the overall topology largely consistent between analyses. We erect a new clade, named Diamantinasauria herein, that also includes the contemporaneous Sarmientosaurus musacchioi from southern Argentina, which shares several cranial features with the referred Diamantinasaurus specimen. Thus, Diamantinasauria is represented in the mid-Cretaceous of both South America and Australia, supporting the hypothesis that some titanosaurians, in addition to megaraptoran theropods and possibly some ornithopods, were able to disperse between these two continents via Antarctica. Conversely, there is no evidence for rebbachisaurids in Australia, which might indicate that they were unable to expand into high latitudes before their extinction in the Cenomanian–Turonian. Likewise, there is no evidence for titanosaurs with procoelous caudal vertebrae in the mid-Cretaceous Australian record, despite scarce but compelling evidence for their presence in both Antarctica and New Zealand during the Campanian–Maastrichtian. These later titanosaurs presumably dispersed into these landmasses from South America before the Campanian (~85 Mya), when seafloor spreading between Zealandia and Australia commenced. Although Australian mid-Cretaceous dinosaur faunas appear to be cosmopolitan at higher taxonomic levels, closer affinities with South America at finer scales are becoming better supported for sauropods, theropods and ornithopods.

Type: Article
Title: Second specimen of the Late Cretaceous sauropod dinosaur Diamantinasaurus matildae provides new anatomical information on skull and neck evolution in early titanosaurs and the biogeographic origins of Australian dinosaur faunas
Open access status: An open access version is available from UCL Discovery
DOI: 10.1093/zoolinnean/zlaa173
Publisher version: https://doi.org/10.1093/zoolinnean/zlaa173
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Australia, Cretaceous, Dinosauria, Gondwana, Mesozoic, palaeobiogeography, palaeontology, parsimony analysis, phylogenetic systematics, Sauropodomorpha
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10114672
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