A "really unusual" discovery of dinosaur teeth in outback Queensland has changed what researchers know about how a 20-tonne titanosaur would have smiled.
New research on 17 curved teeth that were unearthed at a dig site near Winton in 2019 has shed light on sauropod Diamantinasaurus matildae's role in its prehistoric ecosystem.
Australian Age of Dinosaurs museum research associate Stephen Poropat said previous descriptions of the Diamantinasaurus' skull were modelled in part from a comparable titanosaur from Brazil.
"We've found dozens of sauropod skeletons in Winton over the past two decades, and this was the first one that preserved a lot of teeth which is really unusual," Dr Poropat said.
"They are between 98 and 95 million years old, we haven't got an exact date on them yet, but that's the boundary that we're working with at the moment."
He said the teeth showed the dinosaur was probably feeding at least one metre above the ground, not really ingesting much soil or grit, and probably up to 10m above the ground.
"Imagine a three-storey building," he said.
Dinosaur dental important
The "robust and chunky" Diamantinasaurus teeth were a point of difference with other sauropods, which in general had more plentiful, narrower teeth suited for eating lower to the ground.
It was a valuable distinction to make, according to Dr Poropat, who has dedicated part of his career to understanding as much as possible about the titanosaur.
"The fossils that we're finding are all a part of an ancient ecosystem that occupied central Queensland when it was much wetter and quite a bit warmer than it is today, despite the fact that Australia was much further south at that time," Dr Poropat said.
"To be able to understand how many different species of sauropods were coexisting in this area, we need to be able to constrain what each of their diets was, and we can do that using their teeth."
Digging up more
There is still much to learn about Diamantinasaurus matildae, which is in the running to become Queensland's state fossil emblem.
Australian Age of Dinosaurs executive chairman David Elliott said almost two dozen of the titanosaur's teeth had been found.
"We've got enough there, and enough bones from the site, that we can start to fit those teeth to the animal that owns the bones," Mr Elliott said.
"That's really exciting, because up until now we really haven't had much of an idea what the Diamantinasaurus' skull or shape of the face really looks like."
Dr Poropat said the future was bright for the sauropod.
"The good thing is, we do have more specimens of Diamantinasaurus in the pipeline that are going to make our understanding of this animal even clearer in the future," Dr Poropat said.
"We keep digging more up each year."
