When a 6-mile-wide asteroid struck Earth at the end of the Cretaceous period some 66 million years ago, it wiped out the majority of living organisms. Many victims were instantly fried by fires or drowned in tsunamis. The rest, meanwhile, succumbed to hostile conditions and the gradual collapse of entire ecosystems. In the end, about three-quarters of all species were swept into oblivion.
Yet many also survived and, eventually, repopulated the planet. Every living thing today is descended from the resourceful (or lucky) few who found ways to eke out an existence in that apocalyptic landscape. But how did those organisms persist long enough to see the world through to better days?
Which Animals Were Able to Survive the Asteroid Impact?
The challenge to life was immediate — within minutes of the impact, a global pulse of thermal radiation raised Earth’s surface to lethal temperatures. Marine species were safely insulated, but the survival of land-dwellers demands explanation.
In 2004, a University of Colorado Boulder researcher named Douglas Robertson and his colleagues introduced the sheltering hypothesis: The animals with the best shot at lasting through those initial hours were the ones who could escape to cooler environments. From crocodiles and lizards to birds and mammals, as Robertson put it in a later paper, “all the surviving species were plausibly able to take shelter from heat and fire underground or in water.”