Crocodile Relatives Tracked Warm Climates Across 245 Million Years, Preserving Equatorial Refugia After Chicxulub Impact

The Science Advances study combined fossil occurrences, phylogenetic trees, and 245-million-year climate reconstructions to map thermal niches. Crocodylomorphs expanded poleward during greenhouse intervals and contracted to tropics during cooling, a pattern that positioned survivors near the equator when post-impact temperatures plunged. This tracking behavior explains persistence through two mass extinctions despite extreme morphological experimentation from 12-meter predators to pug-faced herbivores.

Prior dinosaur-focused models from the same UCL group showed non-avian habitat loss exceeded 50 percent in most simulations; pseudosuchian refugia remained viable except under the most extreme cooling scenarios. The finding reframes the extinction as spatially heterogeneous rather than globally uniform, highlighting how long-term climate affinity can outweigh short-term adaptability.

What the original coverage underplays is the relevance to current warming: modern crocodylians may again expand from tropics, potentially altering wetland ecosystems and increasing human-wildlife conflict. Future work needs finer-resolution regional climate layers and direct testing against avian survival data to test whether endothermy or nesting behavior provided additional advantages.

Next steps include integrating these niche models with Chicxulub soot-injection simulations and comparing pseudosuchian resilience metrics against other archosaur clades to isolate the precise climatic threshold that determined survival.