In Queensland, Australia, an ichthyosaur fossil nicknamed BOB (Platypterygius australis) revealed a food chain of three levels in the ancient Eromanga sea. High technology scans showed that its stomach had the remains of a flying pterosaur, but the bite marks in its own skeleton show that it also was also attacked by a much bigger marine reptile, probably a Kronosaurus. The findings show how modern technology and fossil research can reconstruct the ecological interactions of the past.
A three-level food chain frozen in stone
With the first scans, fish and squid-like belemnites, shell fragments, and pieces of a pterosaur appeared all together, which made researchers interpret as the fossilized gut contents.
This was considered great evidence because having the prey inside the body is much more reliable than finding the rest of the bones nearby. So here, the sequence starts with a flying reptile that ends up inside a large marine hunter.
The hunter appears to have become food
BOB’s skeleton tells a second, more violent story. Researchers saw that its vertebratae were broken, with missing ribs and areas completely destroyed. Also, a large crushing bite mark shows how the attack happened.
Dr. Matt White said that he was surprised by how the skeleton was damaged, not just by the animal’s size. The team argues that Kronosaurus queenslandicus, a giant pliosaur from the Eromanga Sea, is the only known local predator capable of producing injuries on that scale.
Still, there is some doubt as to whether the Kronosaurus killed the ichthyosaur or if it actually arrived later to the carcass. So the most accurate conclusion is that the larger predator partially ate the animal. Either way, the food chain is super impressive.
How BOB emerged from an ordinary fossil hunt
Instead of breaking the rock and risking irreplaceable evidence, the team worked with the Australian Nuclear Science and Technology Organisation to examine the material using neutron tomography. This method is really good to see inside the object in 3D. So yes, scientists could view the interior without using a hammer on the fossil.
Let’s say that the discovery was divided in two. In August 2019, Mike and Cathy Freeman,Gary and Barb Flewelling, found large fossilized bones at a public fossil hunting site outside Richmond. Here is when they gave it the nickname BOB.
Three years later, Kronosaurus Korner, curator of the Kevin Petersen museum, went back to that same place and found the rest of the ichthyosaur.
It was after much hard work and preparation that they found the unusual nodules behind its skull that were examined with the tomographies.
Today’s dry Outback once lay beneath a dangerous sea
BOB’s discovery shows that food chains crossed between sky and sea, and actually how fast a predator can then become a prey. The pterosaur remains do not prove that this type of prey was part of the daily diet of the ichthyosaur. Still, researchers say that the Platypterygius australis ate a big part of the flying reptile.
It is important to say that the ecosystem around Richmond is not what it was before, because during the Early Cretaceous, most of Queensland was covered by the Eromanga Sea, where ichthyosaurs, giant pliosaurs, plesiosaurs, fish, turtles, sharks, and other marine animals lived.
Why one bag of bones matters so much
Richmond’s public fossil areas gave us thousands of remains, including marine reptiles, pterosaurs, turtles, birds, fish, and dinosaurs. And in this case, BOB gave scientists direct information about who ate whom in an ancient Australian sea.
This discovery ended up being definitely a matter of international importance that started with 4 people who decided that it was worth picking up those bones and going further. It is amazing how big science can start in a very simple way.
