Depending on the load (red arrow), stress is distributed differently across the fossil tooth (blue to yellow scale) | Graphic: M. Greif et al. (2025)

Some 370 million years ago, the shark-like Ctenacanthus was an apex predator in the prehistoric seas. It would catch its prey, then tear out huge chunks by shaking its head laterally. We know this thanks to a mechanical analysis of a fossil tooth using simulated pressure (see the arrows): (a) biting and (b) shaking only cause local stress to the tooth. But holding on to the prey (c, d) distributes stress in a manner that’s unfavourable to the owner of the tooth. According to a research team from the University of Zurich, we may therefore assume that the shark didn’t simply grab its prey and chew.

M. Greif et al.: Reconstruction of feeding behaviour and diet in Devonian ctenacanth chondrichthyans using dental microwear texture and finite element analyses. Royal Society Open Science (2025)