The Discovery
When an asteroid struck Earth 66 million years ago, it triggered a mass extinction that wiped out non-avian dinosaurs. Yet, ancient relatives of modern crocodiles managed to endure. A study led by researchers at University College London and published in Science Advances offers an explanation for their survival. By analyzing more than 7,000 fossils alongside records from over 400 living and extinct species, scientists mapped out reptile habitats using climate and geographic reconstructions spanning 245 million years.
What Scientists Found
The research demonstrated that crocodile relatives spent much of their 250-million-year history following warm environments instead of adapting to vastly different temperatures. When Earth warmed, they expanded into new areas, living at high latitudes in Europe, North America, and Antarctica during warm periods like the early Eocene 50 million years ago. As global temperatures fell, their geographic range contracted back toward the tropics.
The broader crocodile lineage, known as pseudosuchians, was physically diverse. It included:
- Heavily armored plant eaters.
- Land-dwelling hunters like Postosuchus, which moved on two or four legs.
- Giant predators like the 12-meter-long Sarcosuchus.
Despite this variety in lifestyle and body shape, their relationship with climate stayed remarkably consistent. Computer models simulating the environmental impact of the Chicxulub asteroid showed that even if sunlight was reduced by 5% or 10%, equatorial regions remained warm enough to act as crucial refuges. In contrast, suitable habitats for non-avian dinosaurs shrank far more severely.
Why It Matters
These findings explain how crocodile relatives managed to survive two of Earth's five major mass extinctions. While there were rare evolutionary exceptions—such as a lineage that tolerated extreme heat 94 million years ago and an Australian group that adapted to dry deserts 34 million years ago—most species survived by following warm climates. By persisting in equatorial sanctuaries during planetary catastrophes, these surviving populations were able to endure, recover, and eventually spread across the globe.
Source: dinosaur fossil discovery - BingNews · Published October 30, 2026 · Photo by popn kix on Unsplash
