Prehistoric Predator’s Last Meal Revealed through X-Ray Analysis

We now know more about the diet of a prehistoric creature that grew two and a half meters long and lived in Australian waters during the time of the dinosaurs, thanks to the power of X-rays and a team of scientists at The Australian National University (ANU) and the Australian Museum Research Institute (AMRI).

Researchers used microcomputed tomography to look inside the fossilized stomach remains of a tiny marine reptile — a plesiosaurus nicknamed in a song from the Monty Python comedy set — to determine what the creature ate in the lead-up to its death.

The researchers were able to find 17 previously undescribed fish vertebrae inside Eric’s gut, confirming that the plesiosaurus’ diet consisted mostly of fish – reinforcing findings from previous studies conducted in 2006.

The findings could help scientists learn more about the evolutionary history of extinct creatures like Eric, as well as help predict what the future might look like for our marine life. According to the researchers, the study demonstrates the possibility of using X-rays to reconstruct the diets of other extinct organisms that inhabited Earth hundreds of millions of years ago.

“Previous studies examined the opaque exterior of Eric’s skeleton for clues,” Ph.D. said researcher Joshua White, of the ANU Research School of Physics and AMRI.

“But this approach can be difficult and limited because fossilized stomach contents are rare to find and there could be more hidden beneath the surface that would be near impossible for paleontologists to see without destroying the fossil.”

“We believe our study is the first in Australia to use X-rays to study the contents of the gut of a prehistoric marine reptile.”

“Our research used very powerful X-rays to help us see the contents of the animal’s stomach in unprecedented detail, including finding fish bones in its gut.”

“The benefit of using X-rays to study these prehistoric animals is that they don’t damage the fossil, which is very important when dealing with valuable and delicate specimens like Eric’s.”

White sifted through mountains of data and CT images to distinguish between what he believed to be evidence of fish bones, stomach stones, also known as gastric stones, and other substances the reptile consumed. The data was used to create a 3D model of the contents of Eric’s gut.

“Eric was a mid-level predator, sort of the equivalent of a sea lion, eating small fish and likely a much larger predator,” White said.

“We are also fortunate in the sense that Eric is one of the most complete vertebral skeletons in Australia. The fossil is about 93 percent complete which is pretty much unprecedented in any fossil record.”

“No place other than Australia can actually get sterile vertebral fossils.”

ANU scientists say that knowing more about the diet of extinct creatures is an important step in understanding their evolutionary past, but it can also help us understand how animals living today may have been affected by things like climate change.

“As environments change, so does the diet of marine reptiles, and understanding these changes can be used to help predict how today’s animals will respond to current and emerging climate challenges,” White said.

“If there’s been any change in the animals’ diet, we want to look at why that change happened, and by doing some metrics we can compare that to modern animals like dolphins or whales and try to predict how their diet might change because of climate change and why.”

Eric was first discovered in the opal mines of Coober Pedy in South Australia in 1987. This prehistoric predator is on display at the Australian Museum in Sydney.

Research published in Alcheringa: An Australian Journal of Paleontology.