Sixty-six million years ago, a giant asteroid collided with the Earth. The impact caused the extinction of over 75 percent of all life on Earth at the time, including the mighty dinosaurs.

Only a few species that were able to find shelter underground from the immense heat and volcanic ash were able to survive. For instance, all modern snakes evolved from just a few species that survived that impact.

Tree-dwelling animals were especially vulnerable to the impact due to wildfires and global deforestation. Marsupials and Primates were the only arboreal (tree-dwelling) species that survived the Cretaceous-Paleogene extinction event caused by the impact.

New research University of Cambridge, Yale University, and Brooklyn College has revealed why only these two species were able to survive the extinction event.

In a paper published in the journal Ecology and Evolution, researchers suggest that the primates may have left trees for underground shelters to survive the impact.

Using computer models based on fossil records and information from living mammals, the researchers discovered that most surviving mammals did not rely on trees. The arboreal mammals that previously lived on trees, including our primate ancestors, were versatile enough to adapt to living away from trees.

“One possible explanation for how primates survived across the K-Pg boundary, despite being arboreal, might be due to some behavioural flexibility, which may have been a critical factor that let them survive,” said Jonathan Hughes, lead author of the paper, and a doctoral student at Cornell’s College of Agriculture and Life Sciences.

Fossil records show the earliest mammals appearing around 300 million years ago, and researchers think they may have diversified along with flowering plants some 20 million years before the asteroid struck. The event killed off most of the mammal species while allowing the ones that survived to diversify into new ecological niches left open from the disappearance of the dinosaurs.

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