An innovative jaw bone study has revealed that a Jurassic fish ate like modern sea breams.
By measuring the jaws of 89 examples of the fish Dapedium, including specimens from the Natural History Museum, University of Bristol undergraduate Fiann Smithwick was able to recreate how it ate. He said:
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.
A Dapedium specimen from our collections.
The good preservation of the fossil fish specimens allowed Fiann to use a mechanical model developed to understand modern fishes in his study. By calculating the positions and orientations of the jaw muscles, he was able to determine that Dapedium's jaws moved slowly but strongly, allowing it to work on the hard shells of its prey.
In contrast, other families of fish can have faster but weaker jaws, adapted for feeding on fish prey that are speedier and slipperier.
Ancient fish, historic collections
Dapedium lived 200 million years ago during the Jurassic period, and is one of many ancient sea creatures discovered by Mary Anning in the rocks around Lyme Regis, Dorset.
Museum fossil fish curator Emma Bernard said:
Dapedium is an iconic fossil from Lyme Regis and can be found on many postcards and souvenirs from Lyme Regis. If you are lucky you may even find one when fossil hunting in Lyme Regis.
Viewed from the side, Dapedium was a flat, deep-bodied fish that could grow up to half a metre in length. It had jutting front teeth with a mass of blunt teeth behind. Emma said Fiann was a pleasure to work with as he grasped the importance of our historic collections:
This study would not have been possible without the extensive fossil collections we house, which show a variety of characteristics that Fiann used for his study. His work helps us build up a picture of how Dapedium lived and what it ate.
The study appears in the prestigious journal Palaeontology - a rare achievement for an undergraduate.