There Once Was a Shark That Ate an Amphibian That Ate a Fish ...

A fossilized shark that swallowed a crocodile-like amphibian that, in turn, had gobbled up a fish has now been unearthed.

This exceptional find marks the first time scientists have found direct evidence of such a complex, extinct food chain.

In the past, researchers had uncovered evidence of what past species ate based on the fossilized contents of their guts or droppings. For instance, fossilized dung, or "coprolites," have revealed some dinosaurs ate grass.

Prey, especially in the gut or intestines of fossil organisms, are very rarely preserved," said paleobiologist Jurgen Kriwet at Humboldt University of Berlin in Germany. At most, only a single victim or perhaps several of the same species are preserved, he added.

By accident, Kriwet and his colleagues discovered the new shark fossil in a museum collection. These exceptionally preserved remains are roughly 290 million years old, pre-dating the emergence of the dinosaurs.