Research Highlight - Ichthyosaur Flipper Fossil Reveals Ancient Stealth Technology

A team of paleontologists has uncovered evidence that a massive Jurassic marine reptile, Temnodontosaurus, evolved a form of “stealth mode” to silently hunt prey in dimly lit seas 183 million years ago. The study, published in Nature, centers on a remarkably preserved one-meter-long front flipper from Germany’s Toarcian Posidonia Shale.

The fossil reveals extraordinary soft-tissue structures: a wing-like flipper outline, fine parallel skin ridges and a flexible tip, all suggesting aerodynamic finesse. Most strikingly, the trailing edge of the flipper features unique cartilage-based structures called chondroderms, unlike anything previously known in fossil marine reptiles. These elements, embedded within the skin, likely reduced hydrodynamic noise during swimming.

Fig. Skeletal reconstruction and hypothetical soft-tissue outline

Using computational fluid dynamics, researchers showed that these adaptations suppressed low-frequency sound, allowing the visually guided Temnodontosaurus with eyes the size of dinner plates to approach prey undetected. The fossil also reveals high aspect ratio flippers, a trait linked to lift-efficient, gliding motion seen in modern whales.

This discovery documents exceptional soft-tissue preservation; introduces a new anatomical structure; combines morphology with biomechanical modeling; and offers a novel ecological hypothesis—stealth predation in marine reptiles. It even has implications for modern bio-inspired design, like quieter underwater vehicles.

By illuminating how extinct predators fine-tuned their bodies for silent hunting, the study reshapes our understanding of Mesozoic marine ecosystems and shows that stealth isn’t just for submarines.

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Reference

Lindgren, J., Lomax, D.R., Szász, RZ. et al. Adaptations for stealth in the wing-like flippers of a large ichthyosaur. Nature (2025). https://doi.org/10.1038/s41586-025-09271-w