Sauropod dinosaur teeth from the lower Upper Cretaceous Winton Formation of Queensland, Australia and the global record of early titanosauriforms

Stephen F Poropat; Timothy G Frauenfelder; Philip D Mannion; Samantha L Rigby; Adele H Pentland; Trish Sloan; David A Elliott

doi:10.1098/rsos.220381

Sauropod dinosaur teeth from the lower Upper Cretaceous Winton Formation of Queensland, Australia and the global record of early titanosauriforms

R Soc Open Sci. 2022 Jul 13;9(7):220381. doi: 10.1098/rsos.220381. eCollection 2022 Jul.

Authors

Stephen F Poropat^{1

2}, Timothy G Frauenfelder³, Philip D Mannion⁴, Samantha L Rigby^{1

2}, Adele H Pentland^{1

2}, Trish Sloan¹, David A Elliott¹

Affiliations

¹ Australian Age of Dinosaurs Natural History Museum, The Jump-Up, Winton, Queensland 4735, Australia.
² School of Science, Computing and Engineering Technologies, Swinburne University of Technology, John Street, Hawthorn, Victoria 3122, Australia.
³ School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia.
⁴ Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK.

Abstract

The Upper Cretaceous Winton Formation of Queensland, Australia, has produced several partial sauropod skeletons, but cranial remains-including teeth-remain rare. Herein, we present the first description of sauropod teeth from this formation, based on specimens from three separate sites. An isolated tooth and a dentary fragment from the Diamantinasaurus matildae type locality are considered to be referable to that titanosaurian taxon. A single tooth from the D. matildae referred specimen site is similarly regarded as being part of that individual. Seventeen teeth from a new site that are morphologically uniform, and similar to the teeth from the two Diamantinasaurus sites, are assigned to Diamantinasauria. All sauropod teeth recovered from the Winton Formation to date are compressed-cone-chisel-shaped, have low slenderness index values (2.00-2.88), are lingually curved at their apices, mesiodistally convex on their lingual surfaces, and lack prominent carinae and denticles. They are markedly different from the chisel-like teeth of derived titanosaurs, more closely resembling the teeth of early branching members of the titanosauriform radiation. This provides further support for a 'basal' titanosaurian position for Diamantinasauria. Scanning electron microscope microwear analysis of the wear facets of several teeth reveals more scratches than pits, implying that diamantinasaurians were mid-height (1-10 m) feeders. With a view to assessing the spatio-temporal distribution of sauropod tooth morphotypes before and after deposition of the Winton Formation, we provide a comprehensive continent-by-continent review of the early titanosauriform global record (Early to early Late Cretaceous). This indicates that throughout the Early-early Late Cretaceous, sauropod faunas transitioned from being quite diverse at higher phylogenetic levels and encompassing a range of tooth morphologies at the start of the Berriasian, to faunas comprising solely titanosaurs with limited dental variability by the end-Turonian. Furthermore, this review highlights the different ways in which this transition unfolded on each continent, including the earliest records of titanosaurs with narrow-crowned teeth on each continent.

Keywords: Diamantinasauria; Sauropoda; Titanosauriformes; Winton Formation; microwear; palaeobiogeography.