The Discovery

Throughout evolutionary history, numerous groups of land-dwelling reptiles and mammals reversed course and returned to aquatic environments. To better understand how and when these transitions took place, researchers at Yale University conducted a study published in the journal Current Biology. The research was led by Caleb Gordon alongside senior author Bhart-Anjan Bhullar.

The team analyzed hundreds of modern and fossil specimens stored at the Yale Peabody Museum and institutions across the globe. They compiled over 11,000 measurements, photos, and CT scans. By merging traditional paleontology with machine learning models trained on living animals—and applying a statistical technique originally used by naval forces in World War II—they created a novel method to evaluate skeletal proportions and predict adaptations for swimming in extinct species.

What Scientists Found

The researchers applied their new framework to resolve long-standing debates about prehistoric aquatic life:

  • Spinosaurus: This massive dinosaur lived in northern Africa between 113 million and 94 million years ago. Paleontologists previously disagreed over whether it waded in shallow waters like a heron or submerged itself like a seal or penguin. The new analysis indicated highly aquatic habits, demonstrating that Spinosaurus spent the vast majority of its life underwater.
  • Mesosaurs: These small marine reptiles lived 290 million to 274 million years ago in regions that now make up parts of South Africa and eastern South America. Even though they gave birth to live young, their limb proportions suggest they were not built for a strictly underwater existence. Instead, they regularly moved between land and water, behaving similarly to modern alligators or platypuses.

Why It Matters

Determining how ancient species behaved is difficult when different skeletal features provide conflicting signals about whether an animal lived on land or in water. By using machine learning trained on living organisms, this research provides a rigorous way to evaluate how extinct animals adapted to aquatic habitats. The findings offer clearer insight into convergent evolution, illustrating how separate species evolved similar features, such as flippers, when adapting to underwater life.

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Source: prehistoric animals new study - BingNews · Published October 25, 2026 · Photo by Blond Fox on Unsplash