Food Access a Possible Key to Survival Amid Die-Off 65 Million Years Ago

At the end of the Cretaceous period 65 million years ago, about 70% of all species on Earth were destroyed, perhaps by the impact of an asteroid. Researchers have long wondered why some survived while others did not. A new study in Nature today suggests that for at least some species, access to food was the key.

Researchers at the Natural History Museum in London studied fossils of sea urchins and found that those that fed on plankton at the ocean surface were most likely to have been destroyed, because the impact is believed to have killed the plankton there. Those that fed on the bottom mostly survived, the researchers said. The findings also suggest that the die-off began before the catastrophic event, indicating that the climate was already deteriorating.

Compiled by Times medical writer Thomas H. Maugh II