British scientists have discovered the world's oldest fossilized vomit, believed to have come from a large marine reptile 160 million years ago.
The vomit contains the remains of dozens of belemnitessquid-like shellfish that lived in abundance in the seas around what is now Britain. The belemnites were eaten in great numbers by ichthyosaurs, large marine reptiles (related to land-dwelling dinosaurs) common in the warm seas of the Jurassic era, similar in size and shape to dolphins but with pointed snouts full of sharp teeth.
The technicolor yawn was discovered in a clay quarry in Peterborough by the University of Greenwich's Peter Doyle and Jason Wood of the Open University.
Having eaten dozens of belemnites, an ichthyosaur would regurgitate their indigestible bullet-shaped shells in much the same way that an owl does after eating a mouse whole, the scientists announced Tuesday. It is these shells that have been discovered in the fossil vomit.
"We believe that this is the first time the existence of fossil vomit on a grand scale has been proven beyond reasonable doubt," said geologist Professor Doyle. "The Peterborough belemnite shells, viewed under a powerful scanning electron microscope, have revealed 'acid etching' marks caused by digestive fluids from the gut of a marine reptile, proving that the belemnites had been eaten by a predator. The fact that most of these belemnites were juveniles reinforces our view that they did not die of old age."
It was highly unlikely that the shells passed through the ichthyosaurs intestines and were excreted as droppings, as they would have damaged the soft tissue of the reptile's internal organs," Doyle said. "The only alternative is that the shells were vomited out, in much the same way that modern-day sperm whales regurgitate the indigestible beaks of squid they have eaten."
The research was prompted by the discovery of a mass of 180 million-year-old belemnite fossils discovered in the 1990s on what is known as Britain's 'Dinosaur Coast,' near Whitby in Yorkshire.
"Although the Yorkshire fossil belemnites did not show signs of acid etching, we still believed that they were regurgitated," said Doyle. "We just didn't have enough hard evidence to prove it. Now we believe that the acid etching on the Peterborough fossils is the evidence we were looking for."
The large concentration of belemnite fossils in the Peterborough clay quarry suggests that 160 million years ago the area was a shallow-water, coastal feeding ground for belemnites. The abundant shellfish attracted the ichthyosaurs that ate them, which were in turn preyed upon by massive pliosaurs, some of the largest predators ever to have lived, according to University of Portsmouth expert Dave Martill.
The findings of Doyle, Wood and University of Greenwich research student Emma Shakides were presented at a conference at the University of Copenhagen, Denmark in December 2001.
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