As Nature reports, UK researchers are proposing that changes in temperature after a meteor slammed into Earth caused the birth of females to become increasingly rare, until the dinosaur population dwindled to extinction. The theory is based on the fact that the sex of crocodiles, to which dinosaurs are related, depends on the temperature at which their eggs are incubated. Male crocodiles hatch in moderate temperatures, while females emerge if the heat rises or falls by a few degrees.

To illustrate how it could happen, the team built a mathematical model to show how fast a species might become extinct if it deviated from a 50:50 sex ratio. With a ratio of 80:20, the model predicts that a population of 1000 animals would die out within 50 rounds of reproduction, or 500-1000 years.

However, most dinosaur experts believe that dinos are most closely related to birds, which do not use temperature to determine sex. And regardless, the crododiles lived through the same climate shift as the dinosaurs, and they somehow survived.