Eric ate some fish. Then he died

Eric died after eating a diet that mainly consisted of fish. Except Eric died millions of years ago and is also a type of plesiosaur.

Found by an opal miner in outback South Australia 35 years ago, his is one of the most complete skeletons of a plesiosaur discovered in Australia, around 93 per cent intact.

Plesiosaurs were marine reptiles with flipper-like limbs that allowed them to move from land to sea. There were two families within the Plesiosaur order – short-necked Pliosaurs (like Eric) and longer-necked Elasmosaurs, one of which was recently unearthed in remote Queensland.

Performing a micro-CT scan on the fossilised remains of Eric’s stomach, the researchers from the Australian National University, discovered 17 fish vertebrae, likely from a teleost – or ray-finned fish

This is consistent with previous assumptions about the diet of this order of prehistoric replies.

However the findings are notable, at least because of the novel use of x-rays to investigate fossilised remains.

“We believe our study is the first in Australia to use x-rays to study the gut contents of a prehistoric marine reptile,” says lead researcher Joshua White.

A micro-ct scan of the inside of the fossilised stomach remains of a plesiosaur.
A micro-CT scan of the inside of the fossilised stomach remains of a plesiosaur nicknamed ‘Eric’ after a song from the comedy group Monty Python. Credit: Joshua White/ANU

In a CT scan, x-rays are used to peer inside bodies to see what lies within. It’s a common practice in modern medicine, but is increasingly used by palaeontologists and archaeologists to study ancient remains.

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Researchers previously studied the exterior of Eric’s remains, but internal analysis provides a higher level of detail.

“Fossilised stomach contents are rare to find and there can more hidden beneath the surface that would be near impossible for palaeontologists to see without destroying the fossil,” White says.

“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.”

The analysis of Eric’s insides using CT scanning suggests he was a ‘middle order’ predator during the Early Cretaceous period.

But studying the diets of long-dead species has benefits today.

“If there’s any change to an animal’s 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 says.

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