Scientists Uncover the Mechanics Behind a Shell-Crushing Jurassic Fish

Scientists have taken a closer look at the unusual feeding habits of a 200-million-year-old fish. Using a mechanical model, researchers now better understand how this Jurassic fish functioned in the ancient world.

The fish in question is called Dapedium, and is just one of many new groups of fishes that are from the Lower Lias rocks of the Dorset coast around Lyme Regis. This creature was a deep-bodied fish, shaped a bit like a dinner plate in side view, and could grow up to half a meter in length. It had a tiny mouth with jutting front teeth and masses of pebble-shaped teeth further back in its mouth.

In order to better understand the eating behavior of this fish, the researchers applied a level-based mechanical model designed to understand the jaw mechanics of modern fishes. This allowed them to reconstruct the feeding behavior of this ancient fish.

"My work indicates that Dapedium was well adapted to crush shells, feeding on bivalves and other hard-shelled creatures that it could scrape from the sea floor," said Fiann Smithwick, one of the researchers, in a news release.

The researchers calculated the positions and orientations of jaw muscles and varied these to include all possible models. Time and time again, the researchers found the same result; the ancient fish was a shell crusher with slow-moving jaws.

The scientists also compared this ancient fish to modern fishes. Dapedium actually matches closely with the modern sea breams. These fishes are also flat-sided and deep-bodied, and they crush shells in their small mouths.

The findings reveal a bit more about this ancient creature, which tells scientists a bit more about the ancient environment of the Jurassic.

The findings are published in the journal Palaeontology.

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