When it comes to adapting to climate change, diversity is the mammal’s best defense. That is one of the conclusions of the first study of how mammals in North America adapted to climate change in “deep time” – a period of 56 million years beginning with the Eocene and ending 12,000 years ago with the terminal Pleistocene extinction when mammoths, saber-toothed tigers, giant sloths and most of the other “megafauna” on the continent disappeared.

“Before we can predict how mammals will respond to climate change in the future, we need to understand how they responded to climate change in the past,” said Larisa R. G. DeSantis, who directed the study, which was published in the journal Public Library of Science One. “It is particularly important to establish a baseline that shows how they adapted before humans came on the scene to complicate the picture.” Establishing such a baseline is particularly important for mammals because their ability to adapt to environmental changes makes it difficult to predict how they will respond. For example, mammals have demonstrated the ability to dramatically alter their size and completely change their diet when their environment is altered.