3D computer models reveal feeding habits of ‘big-mouthed’ fish

An artist's impression of the Titanichthys, which fed by swimming through the water slowly with its mouth open wide. Mark Witton

Scientists have discovered that one of the largest animals of the Devonian period was a suspension feeder. The findings offer clues into how to protect modern-day species such as baleen whales.

Some 380 million years ago, placoderms – extinct armoured fish that were bigger than a great white shark – roamed the seas and oceans. There were two distinct forms of placoderms during the Devonian period – the giant menacing Dunkleosteus and the ‘big-mouthed’ Titanichthys.

The latter has long been known as one of the largest animals of the Devonian period, with a length likely exceeding five metres and a lower jaw of one metre. However, very little has been known about the feeding habits of Titanichthys.

Last week, scientists from the University of Zurich and the University of Bristol published a studyExternal link on the jaw mechanics of the Titanichthys that could improve the understanding of how to conserve modern-day suspension feeders such as sharks and whales.

In contrast to the Dunkleosteus, which used its strong fangs to bite its prey, the Titanichthys’ jaw is narrow, toothless and without sharp edges suitable for cutting. It also could not to close its mouth fully, which is why paleontologists presumed it was a suspension feeder.

To test the theory, the researchers used a biomechanical analysis to compare the lower jaw of various placoderm and living species with similar features. The team tested the resistance of the jaws by virtually applying forces to the jaws of 3D computer models, using a technique called Finite Element Analysis to assess how likely each jaw was to break or bend.

 “The jaw features of Titanichthys resemble those of other suspension feeders, such as the baleen whale, whale shark or the basking shark,” explains Christian Klug, from the Paleontological Institute of the University of Zurich.

Based on these models, the researchers found that the Titanichthys jaw was more likely to break if it fed on large, hard-shelled prey. As a result, it likely fed by swimming through water slowly with its mouth open wide to capture high concentrations of plankton

The scientists believe that the same methods could be applied to other species to help improve the understanding of the driving factors for the evolution and extinction of species.