Scientists use X-rays to reveal prehistoric predator's last supper

"Understanding these changes can help predict how animals of today will respond to current emerging climate challenges."
Amal Jos Chacko
A collage of the skeleton of Umoonasaurus demoscyllus and its gastric mass
A collage of the skeleton of Umoonasaurus demoscyllus and its gastric mass  

Remember a time when you could not recall your last meal, no matter how hard you racked your brains? Well, you'd be in luck if you were a plesiosaur. 

Researchers in Australia can now tell us more about the diet of the prehistoric creature with the power of X-rays, reports

A team of scientists at The Australian National University (ANU) and the Australian Museum Research Institute (AMRI) studied fossilized stomach remains of Eric – a plesiosaur named after the comedy group Monty Python’s song – and found 17 previously unknown fish vertebrae.

Their research published in Alcheringa: An Australasian Journal of Palaeontology indicates a fish-dominated diet, bolstering previous studies conducted on plesiosaurs in 2006.

“Previous studies examined the exterior surface of Eric’s opalized skeleton to find clues,” Ph.D. researcher Joshua White from the ANU Research School of Physics and the AMRI told

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

White believes their study using X-rays to analyze the gut contents of a prehistoric marine reptile to be the first in Australia. 

The team combed through data and CT images and found fish bones, stomach stones, and other materials the reptile had consumed. A 3D model was then created using this data.

“The benefit of using X-rays to study these prehistoric animals is that it does not damage the fossil, which is incredibly important when dealing with valuable and delicate specimens such as Eric,” he added while talking about using powerful X-rays to see stomach contents in detail never seen before.

Scientists use X-rays to reveal prehistoric predator's last supper
Fish bones observed during the study

White describes Eric as a mid-tier predator that feasted on small fish, like the sea lions of today, and likely preyed upon by larger apex predators.

“There is practically nowhere else other than Australia that can actually get opalized vertebrae fossils. We are also lucky in the sense that Eric is one of the most complete opalized vertebrae skeletons.”

Eric, discovered in the opal mines of Coober Pedy, Australia, in 1987, is approximately 93 complete, a feat pretty much unheard of in any fossil record. 

The team shares how studying the diet of now-extinct organisms can not only help us understand their past but also shine a light on how organisms of today can be influenced by factors including climate change. 

“If there’s any change to an animals’ diet, we want to look at why this change occurred and by some measure we can compare this to modern animals such as dolphins or whales and try to predict how their diets might change due to climate change and why,” White concluded.

The study was published in Alcheringa: An Australasian Journal of Palaeontology.

Study Abstract:

The holotype of Umoonasaurus demoscyllus (AM F.99374) is one of the most complete plesiosaur skeletons ever discovered in Australia. It preserves a gastric mass in the pectoral girdle region that has not yet been documented in detail. Here, we use high resolution micro-computed tomography (micro-CT) to image the gut contents of this specimen. These comprise 17 vertebrae from an unidentified teleost, together with at least 60 rounded gastroliths averaging about 5 mm in maximum length. Our study demonstrates the potential for 3D tomographic imaging to investigate Mesozoic marine reptile diets and ecology.

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