Rare 95-Million-Year-Old Dinosaur Skull Uncovered in Australia

The first-of-its-kind find reveals how sauropods may have moved between Australia and South America during the mid-Cretaceous

head of a long-necked dinosaur
An illustration of Diamantinasaurus matildae Elena Marian / Australian Age of Dinosaurs Museum of Natural History

Scientists have excavated the first near-complete skull of a sauropod to ever be found in Australia. Nicknamed “Ann,” the long-necked specimen is just the fourth of the species Diamantinasaurus matildae ever uncovered. 

Such a find is “quite rare,” lead researcher Stephen Poropat of Australia’s Curtin University tells the Guardian’s Donna Lu. It was “really amazing to be able to find a skull at all… and even more so to get so much of one that had been preserved.”

Now, the 95-million-year-old fossil is revealing insights into how dinosaurs may have traveled between continents. In a paper published last week in Royal Society Open Science, Poropat and his colleagues detail the similarities between Ann and another sauropod discovered in Argentina and described in 2016. The authors suggest these dinosaurs may have traveled between South America and Australia by crossing Antarctica during the mid-Cretaceous.

“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,” Poropat says in a statement. At that time, Australia, Antarctica, New Zealand and South America were all connected in a southern landmass known as Gondwana. “In that climate, Antarctica was forested and might have been an attractive habitat or pathway for wandering sauropods.”

The new skull of D. matildae is nearly indistinguishable from that of the Argentinian dinosaur, Sarmientosaurus musacchioi. Based on similarities in the part of the skull surrounding the brain, the bones at the back end of the jaw joint and the curved and conical teeth, the new fossil supports the idea that these two dinosaurs were close relatives, per the statement.

“This is a remarkably detailed and information-packed paper,” Matthew Lamanna, a paleontologist at the Carnegie Museum of Natural History who was not involved with the new study but helped describe S. musacchioi in 2016, tells Live Science’s Sascha Pare. “The resemblances between the skulls of Diamantinasaurus and the similarly aged Sarmientosaurus from southern South America are pretty striking.”

Both of these reptiles were titanosaurs, or massive sauropods that lived around 66 million to 145 million years ago. Titanosaurs include some of the largest land animals to ever exist—some could measure up to 123 feet long. D. matildae, however, was medium-sized, growing to about 65 feet and weighing up to roughly 27 tons (54,000 pounds). Researchers estimate Ann was likely about 50 feet from head to tail. 

The discovery of Ann is helping uncover more details about D. matildae. For one, scientists can now create a loose reconstruction of how the dinosaur’s face might have looked. Because the creature had a rounded snout, paleontologists conclude it browsed for foliage at varying heights rather than always feeding low to the ground, per the Guardian.

Not only is Ann the first Diamantinasaurus uncovered with a mostly preserved skull, but it’s also the first fossil of the species with a preserved back foot, per the statement. While fossils of large titanosaur limb bones can largely resist decomposition, their relatively smaller skulls are much more rare. Sauropod skulls consist of delicate bones held together by soft tissue and may have been prime targets for predators, Poropat writes in the Conversation

During the excavation of Ann, which took place in 2018, the skull’s pieces were found scattered over a roughly 100-square-foot area with the animal’s back leg bones. But after a volunteer found a bone that turned out to be part of the brain case, Poropat tells the Guardian, “that then made all the other bits fall into place.”

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