A 95-million-year-old dinosaur skull discovered in Winton, Queensland has been identified by paleontologists as the first nearly complete sauropod skull ever found in Australia.
The skull belongs to a Diamantinasaurus matilda dinosaur, nicknamed Ann, lived between 95 and 98 million years ago. It is only the fourth specimen of this species ever discovered.
The study’s lead researcher, Dr Stephen Poropat of Curtin University, said it was ‘truly amazing to be able to find a skull – they’re quite rare, and even more so to get so much of one that had been preserved.’
Sauropods were a group of long-necked dinosaurs that included Brachiosaurus and Brontosaurus. They had skulls that were small in relation to their body size, with delicate skull bones.
“They would have made a good target for a predatory dinosaur or even a scavenger animal,” Poropat said. “They would have looked at a sauropod carcass and [thought]: ‘The easiest thing to take away is their head.’”
He said that with previous sauropod discoveries, “sometimes you’ll go through a series of neck vertebrae and eventually come up with nothing because the head was gone.”
Diamantinasaurus matilda it was a titanosaur, a type of sauropod that included the largest land animals to have existed historically. The discovery of the Diamantinasaurus skull allows scientists to recreate for the first time what the dinosaur’s face might have looked like.
“In some ways, the head looks a lot like that of the Brachiosaurus,” Poropat said, noting that there were some differences in the shape and teeth.
“Why [Diamantinasaurus] it has a rounded snout instead of a squared snout, we can tell it was a generalist browser – it did not habitually feed close to the ground.
“When we see sauropods that eat little, they tend to have much narrower teeth. They tend to have squared off snouts, almost like vacuum cleaners.”
The skull of Diamantinasaurus bore many similarities to another titanosaur, Sarmientosaurus musacchioi, who lived in South America at the same time. “You could almost put Sarmientosaurus’ head on Diamantinasaurus’ body and barely be able to make out,” Poropat said.
The researchers believe the discovery strengthens the hypothesis that during the mid-Cretaceous period – 95 to 100 million years ago – sauropods crossed South America and Australia, using Antarctica as a route.
“Because the world was extremely hot … the poles were covered in vegetation, not covered in ice,” Poropat said. “It would appear that sauropods have taken advantage of this really warm period.”
Ann probably measured 15 to 16 meters long from head to tail. The maximum size for Diamantinasaurus is about 20 meters long, 3 to 3.5 meters high at the shoulders, weighing 23 to 25 tons.
“As far as sauropods go, they’re medium-sized,” Poropat said. “The biggest [sauropods] push 40 meters in length and 80 tons in mass”.
The skull of Diamantinasaurus was found during an excavation in 2018, but has not been reported until now. The process involved removing topsoil after bone fragments were found on the surface.
“We started out by finding mainly limb bones and vertebrae, but around one of the limb bones there were small bones scattered around and… it was difficult to place what they were,” Poropat said.
Mel O’Brien, a volunteer, later found “a really strange looking piece of bone that we finally realized must be a braincase. This then caused all the other pieces to fall into place – we realized we had a skull that had basically exploded and the pieces were scattered around the back leg bones.
The excavation was conducted in collaboration with the Australian Age of Dinosaurs Museum of Natural History, citizen scientists and volunteers.
The study was published in the Royal Society Open Science journal.