Titanosaurian sauropod dinosaurs were diverse and abundant throughout the Cretaceous period, with a global distribution. However, few titanosaurian species are represented by multiple skeletons, let alone skulls. Diamantinasaurus matildae, from the Late Cretaceous Winton Formation of Queensland, Australia, was represented by three specimens, including one that preserves a braincase and several other skull elements. In their new paper, paleontologists from Curtin University and elsewhere described a fourth specimen of Diamantinasaurus matildae that preserves a more complete skull — including numerous skull elements not previously known for this species — as well as a partial skeleton.
Life reconstruction of the head of Diamantinasaurus matildae. Image credit: Elena Marian.
Diamantinasaurus matildae lived during the early Late Cretaceous epoch, about 94 million years ago.
This dinosaur was first described and named in 2009 based on fossil finds in the Winton Formation of Australia.
Diamantinasaurus matildae was a medium-sized titanosaurian, measuring 16 m (52 feet) long and weighing up to 25 tons.
Only three specimens, including one that preserves a braincase and several other skull elements, were previously known.
Nicknamed ‘Ann,’ the new specimen preserves a more complete skull, including numerous skull elements not previously known for Diamantinasaurus matildae.
“‘Ann’ is the first sauropod dinosaur found in Australia to include most of the skull, and also the first Diamantinasaurus matildae specimen to preserve a back foot,” said Curtin University paleontologist Stephen Poropat.
“I was lucky enough to be involved in this Australian-first discovery. Being able to lead the research on these fossils was a huge privilege.”
“This skull gives us a rare glimpse into the anatomy of this enormous sauropod that lived in northeast Australia almost 100 million years ago.”
“In analyzing the remains, we found similarities between the ‘Ann’ skull and the skull of a titanosaur called Sarmientosaurus musacchioi, which lived in South America at about the same time as Diamantinasaurus matildae lived in Queensland.”
“These include details of the braincase, the bones forming the back end of the skull near the jaw joint, and in the shape of the teeth (which are conical and curved).”
The reconstructed skull of Diamantinasaurus matildae. Scale bars – 10 cm. Image credit: Poropat et al., doi: 10.1098/rsos.221618.
“Our research suggests that Diamantinasaurus matildae was one of the most ‘primitive’ titanosaurs,” he said.
“Gaining a better understanding of this species might explain why titanosaurs were so successful, across so much of the world, right until the end of the Age of Dinosaurs.”
The findings support previous theories suggesting that sauropods were using Antarctica as a pathway between South America and Australia between 100 and 95 million years ago.
“We suggest that sauropods were traveling between Australia and South America, via Antarctica, during the mid-Cretaceous,” Dr. Poropat said.
“Warmer conditions that far south might have been favorable for them.”
“The window between 100 and 95 million years ago was one of the warmest in Earth’s geologically recent history, meaning that Antarctica, which was more or less where it is now, had no ice.”
“Similarly, Australia, which was much further south than today, was warmer with less seasonality.”
“In that climate, Antarctica was forested, and might have been an attractive habitat or pathway for wandering sauropods.”
A paper on the findings was published in the journal Royal Society Open Science.
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Stephen F. Poropat et al. 2023. A nearly complete skull of the sauropod dinosaur Diamantinasaurus matildae from the Upper Cretaceous Winton Formation of Australia and implications for the early evolution of titanosaurs. R. Soc. open sci 10 (4): 221618; doi: 10.1098/rsos.221618
