It's a Shark Eat Amphibian Eat Fish World!

Permian-period sharks—like the one in the fossil—were only 19 inches (50 centimeters) long and ambushed their prey, swimming up from behind and swallowing it whole.

The fossilized amphibian is also in exactly the right position to suggest it had been eaten—it was lying tail-first along the shark's digestive tract, according to Kriwet.

"Also, the fish remains are fully enclosed within the amphibian's outer covering of scales," he added. That confirms that it was indeed eaten by the amphibian and not the shark.

Before the shark ate it, the amphibian had caught a young fish known as an acanthodian, which was covered in bony spines.

"The fish was swallowed side on, otherwise the spines could have got stuck in the amphibian's mouth or throat," Kriwet said.

"The fish is situated in quite the correct area of digestive tract of the amphibian," said said study co-author Ulriche Heidtke, a paleontologist from the National History Museum of the Palatinate in Bad Dürkheim, Germany.

"It clearly shows the hallmarks of digestion, [such as] disintegration," he added.

That's an interesting contrast with the body fossils found recently: no scales.