The dinosaur-killing asteroid impact radically altered Earth’s tropical forests

Sun-laden, open-canopied forests were transformed into the dark, dense ones seen today

tropical rainforest in Colombia

The origins of modern tropical rainforests, such as this stretch of forest near Medellín, Colombia, trace back to the extinction event at the end of the Cretaceous Period, 66 million years ago.

Christian David Garcia/EyeEm/Getty Images

The day before a giant asteroid hit Earth 66 million years ago, a very different kind of rainforest thrived in what is now Colombia.