Tens of millions of years ago, plate tectonics set North and South America on an unavoidable collision course that would change the face of the Earth and spell life or death for thousands of species. Juan D. Carrillo explains the massive biological repercussions of this collision, which caused one of the greatest episodes of biological migration in history: The Great American Biotic Interchange. Lesson by Juan D. Carrillo, animation by TED-Ed.