The vertebra of an elaphrosaurus has recently been identified in Australia. This is a rare finding which suggests that these dinosaurs were more common than previously thought.
Élaphrosaurus belongs to the theropod family, like the T-Rex. Physically, these dinosaurs were about two meters high and about five meters long. They had a long neck and had small arms at the end of which were four fingers. In addition, they appeared to have developed an unusual diet (we will come back to this later).
So far, remains of elaphrosaurs have been discovered in Tanzania, Argentina and China, but it appears that these dinosaurs have actually conquered other territories. Recently, paleontologists from Swinburne University of Technology (Melbourne) have discovered, in Australia this time, a vertebra of one of these theropods, 110 million years old. A first which is the subject of a publication in the journal Gondwana Research.
From pterosaur to theropod
The vertebra in question, which is about five centimeters long, was found in 2015 near Cape Otway, in the south of Australia. Based on the elongated shape of the bone, paleontologists first suggested that it once belonged to a pterosaur (flying reptile), rather than a dinosaur. It was also labeled as such in the collection of the Melbourne Museum, where it has since rested.
But there was obviously a “mistake on the person”. Stephen Poropat, paleontologist at Swinburne University of Technology, realized this a few weeks ago when he started researching Australian pterosaurs.
“I had heard of this beautiful vertebra in the collection. It was written pterosaur on the label and had been identified [as such] by the person who prepared it, he said. But the vertebrae of the pterosaurs’ neck are very distinctive. They all have a ball at the head and a socket at the tail. But this bone had alveoli, or concave surfaces, at both ends, which means it couldn’t belong to a pterosaur. ”
Based on this observation, Stephen Poropat and his team therefore started from scratch to try to identify the real species concerned. After establishing that the bone came from a theropod, they finally stopped on a Jurassic dinosaur: Elaphrosaurus which is known for its cervical vertebrae “about four times longer than tall”, which is unusual for theropods.
What does this discovery teach us?
While this Australian elaphrosaurus is only known by one bone, its Chinese parent Limusaurus, from the Jurassic era, is much more represented in the fossil records. We know, for example, that the youngest specimens had sharp teeth which they then lost once they reached maturity. In other words, it has been suggested that these dinosaurs probably went from a carnivorous diet during childhood, to a herbivorous diet – or at least omnivorous – in adulthood.
“The juveniles had teeth, while the adults had a beak,” says the paleontologist. Presumably, this indicates a change in diet. I guess they were mostly herbivores [as an adult], but they could still sometimes attack small animals, such as opportunistic predators. ”
It is therefore possible that Australian elaphosaurs, whose species has not yet been officially named, had the same nutritional characteristics.
In addition, this vertebra also teaches us that these dinosaurs were probably more widespread than we thought.
Considering that Australia was much further south 110 million years ago, these Victorian dinosaurs were visibly also very comfortable in the polar regions. The world was certainly much warmer during the Cretaceous, but these animals would still have had to endure several months of darkness during the winter and temperatures which periodically fell below freezing.