Ichthyosaurs had a specialised serrated fin for sneaking up on prey in dimly lit parts of the ocean, new fossil evidence suggests.
The giant ancient sea dwellers are reptiles that transitioned back to living under water, much like the mammalian ancestors of dolphins and whales. The researchers say that modern shipping and sonar is disrupting the hearing of today’s ocean-dwellers, but the fin serrations and surface texture of ancient ichthyosaurs could help human engineers reduce our noise pollution in the sea.
John Lindgren and colleagues present fossil evidence of a unique front flipper from an ichthyosaur which lived between 183 and 181 million years ago. The flipper fossil, excavated in southwest Germany, is approximately one meter long and features a wing-like shape with a serrated edge and a flexible tip.
Lindgren and colleagues suggest that the fin was used by the reptile during hunting. More specifically, through computer fluid dynamics simulations, the authors propose that the serrations on the fin likely helped reduce noise from the reptile as it hunted prey in dimly lit marine environments.
The authors note that hearing has long been a crucial sense amongst seafaring creatures, and in the modern day, that sense is disrupted by human activity, such as shipping activity and military sonar. Lindgren and colleagues suggest that the fin serrations and surface texture of the Ichthyosaurs could serve as a blueprint to reduce noise pollution in the open ocean.