🌅 How Crocodiles Outlasted the Dinosaurs

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SOURCE

Chiarenza et al. (2026)

WHAT TO KNOW

• Researchers at University College London in the U.K. analyzed fossils and records of over 400 crocodile species and their ancient relatives, comparing them with 52 reconstructions of the Earth’s climate stretching back 245 million years. Using simulations, the researchers found crocodile relatives spent much of their evolutionary history moving with changing climates rather than adapting to new ones, uncovering a clear pattern of ancient crocodiles spreading polewards during warm periods and migrating back toward the equator when the climate cooled down.

WHY IT MATTERS

• To understand how crocodiles survived the asteroid that killed the dinosaurs 66 million years ago, the team analyzed different climate conditions that may have changed following the impact, including reduced sunlight caused by ash and dust. The team found at both 5% and 10% reduced sunlight scenarios, regions around the equator remained suitable for crocodile relatives to persist. The findings suggest tropical and subtropical regions were warm enough to support crocodile relatives after the impact, indicating crocodiles’ long-standing preference for warmer environments may have placed survivors in regions where suitable climates held up best. Put simply, while temperature alone doesn’t explain why crocodiles survived, their preference for warmth may have given them a crucial advantage during one of Earth’s greatest mass extinctions.

CONNECT THE DOTS

• Across nearly a quarter of a billion years of crocodilian evolution, the team found only two occasions in which the animals adapted to their environment rather than simply moving somewhere else more suitable. First, during the Cretaceous Thermal Maximum around 94 million years ago, when global temperatures climbed as high as 57 degrees Fahrenheit above modern levels, causing a branch of the crocodile family tree to evolve to tolerate much hotter conditions than the broader lineage could withstand. A second adaptation later occurred around 34 million years ago in Australia, when a prolonged cooling period reduced rainfall and dried out the continent, leading an extinct group of crocodiles to adapt to increasingly arid, desert-like environments.