Warm hiding places near the equator may explain how crocodiles outlived the asteroid that ended the dinosaurs

Crocodiles have a reputation as living fossils that never changed — but a team led by University College London researchers has found their ancestors changed a great deal, with one steady habit: they followed the warmth. Combining more than 7,000 fossil records, an evolutionary tree of over 400 living and extinct species, and 52 reconstructions of ancient climates spanning 245 million years, the team showed crocodile relatives spread toward the poles in hot eras and retreated to the tropics as the planet cooled. Then they tested the worst day in that long history: the asteroid strike 66 million years ago that wiped out the non-bird dinosaurs. In simulations where sunlight fell by 5% or 10%, warm refuges near the equator stayed suitable for crocodile relatives; only an extreme, sustained 15% dimming — beyond most estimates — left them nowhere to go. Warmth alone was not the whole story: small bodies, flexible diets and life half in the water likely helped too. The lesson reaches into the present, the researchers say: species survive change when they can move to places that still suit them — which is why roads, farms and cities blocking that movement matter.