Paleontologists Uncover Weewarrasaurus pobeni: Fossilized Remains of Baby Ornithopod Dinosaurs in Australia
Paleontologists have unearthed the 100-million-year-old (Cretaceous period) fossilized bones of perinatal non-iguanodontian ornithopods in the Griman Creek Formation in central-northern New South Wales, Australia. The fossils provide the first evidence of perinatal dinosaurs from Australia and, more broadly, the first insights into the high-latitude breeding preferences of non-iguanodontian ornithopods in Gondwana.
The newly studied fossils belong to a species of small-bodied ornithopod dinosaur very similar to Weewarrasaurus pobeni.
To estimate the individuals’ age, the researchers used growth rings in the dinosaur bones, similar to the rings in a tree trunk.
“Age is usually estimated by counting growth rings, but we couldn’t do this with our two smallest specimens, which had lost their internal detail,” said Justin Kitchener, a PhD student in the School of Environmental and Rural Science at the University of New England.
“To get around this, we compared the size of these bones with the size of growth rings from the Victorian dinosaurs. This comparison confidently places them at an early growth stage, probably prior to, or around the point of hatching.”
Approximately 100 million years ago, when these dinosaurs were being born, Australia was much closer to the South Pole.
“Southeastern Australia would have been between 60°S and 70°S, equivalent to modern day Greenland,” the scientists explained.
“Although the climate at these latitudes was relatively warmer than they are today, like some Antarctic penguins, these dinosaurs would have endured long dark winters and possibly burrowed or hibernated to survive.”
“Because they are so delicate, egg shell and tiny bones rarely survive to become fossils.”
“We have examples of hatchling-sized dinosaurs from close to the North Pole, but this is the first time we’ve seen this kind of thing anywhere in the Southern Hemisphere,” said Dr. Phil Bell, a paleontologist in the School of Environmental and Rural Science at the University of New England.
“It’s the first clue we’ve had about where these animals were breeding and raising their young.”
The findings appear in the journal Scientific Reports.
J.L. Kitchener et al. 2019. High-latitude neonate and perinate ornithopods from the mid-Cretaceous of southeastern Australia. Sci Rep 9, 19600; doi: 10.1038/s41598-019-56069-8