Did these massive carnivorous dinosaurs hunt beneath the water's surface?

Nature · Published 12 October 2026 Swipe more like this →

In short: For a long time, scientists believed all dinosaurs were strictly land-dwellers. However, new evidence regarding bone density suggests that certain species, like the Spinosaurus, may have been semi-aquatic hunters, submerging themselves to pursue prey in a lifestyle unique among the dinosaurs.

The debate over whether dinosaurs were exclusively terrestrial has been challenged by recent studies into bone density. By comparing hundreds of living and extinct species, researchers found that the bone density of Spinosaurus is similar to that of modern diving animals. This physiological trait suggests that Spinosaurus and its close relative, Baryonyx, may have submerged themselves underwater to hunt aquatic prey, such as the giant freshwater fish Onchopristos. The giant freshwater fish Onchopristis served as a primary target for these predators. This research builds on previous theories suggesting that spinosaurs spent much of their lives in water.

This discovery highlights a significant diversity in spinosaur behavior that was previously underestimated. While Spinosaurus and Baryonyx appear to have been capable of underwater foraging, other spinosaurs like Suchomimus may have simply waded along the shoreline. This specialized niche makes them outliers; while many animal groups have transitioned to aquatic life, dinosaurs generally did not reinvade the water, making the semi-aquatic nature of spinosaurs quite rare. This behaviour was much more diverse than scientists had previously thought. Such a lifestyle distinguishes them from most other dinosaur species.

The research, led by Dr. Matteo Fabbri and published in Nature, utilized the bone density of postcranial skeletons as a proxy for aquatic adaptation. This method relies on the principle that mammals adapted to water possess dense, compact bones. While the exact reasons why dinosaurs as a group did not widely re-enter the water remain a mystery, the evidence for the semi-aquatic lifestyle of these specific spinosaurs is increasingly compelling. The study's findings were made possible by examining the Museum's Baryonyx specimen. This work helps resolve long-standing questions about whether semi-aquatic dinosaurs actually existed.

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