In Australia, researchers have unearthed the first nearly complete sauropod skull ever discovered. The long-necked creature, known as "Ann," is just the fourth specimen of the Diamantinasaurus matildae species to be discovered.
An illustration of Diamantinasaurus matildae Elena Marian / Australian Age of Dinosaurs Museum of Natural History
Such a discovery is "quite rare," lead researcher Stephen Poropat of Curtin University in Australia told Donna Lu of the Guardian. Finding a skull at all was "really amazing, but getting so much of one that had been preserved was even more amazing."
The 95-million-year-old fossil is now providing new information about how dinosaurs might have crossed continents. Poropat and his coworkers highlight the similarities between Ann and another sauropod found in Argentina and detailed in 2016 in a paper released last week in Royal Society Open Science. The authors speculate that during the middle Cretaceous, these dinosaurs might have crossed Antarctica to get from South America to Australia.
"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," adds Poropat in a release. At the time, a southern landmass known as Gondwana united Australia, Antarctica, New Zealand, and South America. Antarctica was forested and may have made a desirable home or travel route for roving sauropods in that environment.
The new skull of D. matildae resembles Sarmientosaurus musacchioi, an Argentinian dinosaur, almost exactly. According to the statement, the new fossil supports the theory that these two dinosaurs were close relatives because of similarities in the region of the skull that surrounds the brain, the bones at the back end of the jaw joint, and the curved and conical teeth.
Matthew Lamanna, a paleontologist at the Carnegie Museum of Natural History who was not involved in the current study but contributed to the description of S. musacchioi in 2016, says of the paper, "This is a remarkably detailed and information-packed paper." The skulls of Sarmientosaurus from southern South America and Diamantinasaurus, which are both of similar age, share some startling similarities.
These two reptiles were titanosaurs, which were large sauropods that existed between 66 and 145 million years ago. Some titanosaurs may reach lengths of 123 feet, making them among the biggest land animals to have ever lived. D. matildae, on the other hand, was medium-sized, reaching a height of around 65 feet and a maximum weight of about 27 tons (54,000 pounds). Ann, according to researchers, was about 50 feet long from head to tail.
More information about D. matildae is being uncovered thanks to Ann's finding. One benefit is that researchers may now make a rough reconstruction of the dinosaur's face. According to the Guardian, paleontologists believe the animal browsed for vegetation at various heights because of its rounded nose, as opposed to always grazing close to the ground.
According to the announcement, Ann is not only the first Diamantinasaurus fossil discovered with a well preserved skull, but it is also the first fossil of the species with a preserved rear foot. Large titanosaur limb bone fossils can mostly withstand degradation, but their relatively diminutive skulls are much more difficult to find. According to Poropat in the Conversation, sauropod skulls may have made excellent prey for predators since they are made of delicate bones held together by soft tissue.
The skull's fragments and the animal's back leg bones were discovered during Ann's excavation in 2018, which covered an area of around 100 square feet. However, Poropat told the Guardian that after a volunteer discovered a bone that turned out to be a component of the brain case, "that then made all the other bits fall into place."
