Two predators, two prey, but only three animals (Image: 2012 Frey, Tischlinger)
The swooping pterosaur snatched a fish from the water, only to be caught by a much bigger fish leaping into the air
Discovered: Solnhofen, Germany, 2009
Age: 155 million years
Location: Wyoming Dinosaur Center, US
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The pterosaur flew just above the water of the tropical lagoon. Snap! It snatched a small, herring-like fish from the water and began to swallow it. But the noise attracted a predator. Up popped Aspidorhynchus, a sleek fish about 60 centimetres long. The fish leaped out of the water and grabbed the pterosaur by its left wing as it was flying. All the animals then splashed down into the water.
But the Aspidorhynchus had bitten off more than it could chew. It didn’t have wide jaws and cutting teeth capable of dealing with such large prey. Its narrow jaws, ending in a pointed snout, were lined with lots of small, sharp teeth best suited to catching other fish. These teeth became entangled with the tough fibres, or aktinofibrils, that reinforced the wing membranes of the pterosaur, Rhamphorhynchus muensteri.
The fish tried desperately to shake itself free, damaging the bones of the wing. During this struggle the pterosaur drowned with the small fish it had caught halfway down its throat. The Aspidorhynchus struggled futilely to disentangle itself as it sank into deeper water low in oxygen and died. The bodies of all three animals ended up on the bottom of the lagoon and there they remained, beautifully preserved, until they were dug up 150 million years later.
This is the scenario proposed in 2012 by Eberhard Frey of the Karlsruhe State Museum of Natural History in Germany after he studied the fossil (). We cannot be sure about all the details but there’s no doubt that the pterosaur had just caught a fish, only to be caught by a fish itself. “The attack was a lethal error on the side of Aspidorhynchus,” Frey says.
More than 100 fossils of Rhamphorhynchus have been found, making it one of the best known of the early pterosaurs, with their characteristic long tails. The shape of their brains supports the idea that they were highly skilled flyers. And there is abundant evidence that they lived near sea shores and preyed on small fish, says Mark Witton at the University of Portsmouth, author of the book Pterosaurs.
But how Rhamphorhynchus caught fish isn’t clear, and this fossil does not make it any clearer. “Was it doing this while floating or swimming, by diving from above or dip-feeding? Or all of the above?” asks Witton.
Frey has proposed that the Rhamphorhynchus was skim-feeding – flying along with its lower beak in the water. The noise of skimming is what attracted the Aspidorhynchus, he suggests.
The idea that some pterosaurs skim-feed was first suggested more than a century ago, says Witton, and has persisted ever since. But he thinks recent studies rule it out – no pterosaur had any of the numerous specialisations seen in modern skim-feeding birds, such as a streamlined lower jaw and reinforced skull to withstand the high-speed impact. “I, and a number of other pterosaur workers, are very sceptical about skim-feeding,” says Witton.
What about swimming or diving for prey? Pterosaurs are sometimes depicted floating on the water in a similar position to that of aquatic birds, but computer modelling by David Hone of Queen Mary University of London, suggests and their mouths very close to the water surface – a very awkward posture. They could swim, he suspects, but not very well. So it seems most likely they flew low and briefly dipped their jaws into the water to grab prey.
And yet it also seems Aspidorhynchus made the mistake of trying to eat Rhamphorhynchus surprisingly often. Three other fossils show the same two species close, although not tangled together. In all four cases, it appears the fish caught the pterosaur but couldn’t quite swallow it. The idea that fish could grab fast-flying animals out of the air might sound improbable but last year came confirmation that . Perhaps Aspidorhynchus also routinely caught small fliers, and occasionally bit off more than they could chew.
Read more: “Stunning fossils: The seven most amazing ever found“
