What opal fossils tell us about giant Australian dinosaurs

ARC Discovery Early Career Researcher Award (DECRA) recipients, Dr Nicolás Campione and Dr Phil Bell, and PhD candidate Timothy Frauenfelder, from the University of New England, have been studying opalised dinosaur teeth to help paint a picture of the eating habits and lifestyles of the largest land animals to ever roam the planet: sauropods.

The teeth were found near the town of Lightning Ridge and are ~100 million years old. Confident in the knowledge that sauropod tooth fossils with different shapes came from different species, this research identified 5 ‘morphotypes’ or tooth-shape categories from the 25 teeth that were studied. By comparing these teeth with the teeth of better-known sauropods, the researchers identified at least three distinct species that would have cohabited the area.

The researchers also studied microscopic scratches and pits, known as ‘microwear’, on the surfaces of each tooth that formed when the animal was biting into its food. By analysing these marks, the researchers could identify the grittiness or smoothness of the dinosaur’s diet, which indicated that they coexisted by eating different things; one species likely fed on soft vegetation between 1 to 10 m above the ground, whereas another ate coarser vegetation less than 1 m above the ground.

‘While we couldn’t assign the 25 tooth fossils to specific species (as we’d need more than just teeth to identify a dinosaur species), we do know all the teeth belonged to a large group of sauropods known as Titanosauriformes,’ Mr Frauenfelder says.

This discovery contributes significantly to the very limited understanding of the sauropods that once inhabited New South Wales.

	‘Our research may have been limited to teeth, but it demonstrates even incomplete fossils can provide key insights into the lives of long-extinct creatures’. Mr Timothy Frauenfelder.