Tens of millions of years ago,a force of nature set two giant masses on an unavoidable collision course that would change the face of the Earth and spell life or death for thousands of species.
The force of nature was plate tectonics, and the bodies were North and South America.
And even though they were hurdling towards each other at an underwhelming 2.5 cm per year, their collision actually did have massive biological reprocussions by causing one of the greatest episodes of biological migration in Earth's history: The Great American Biotic Interchange.
