When the Isthmus of Panama rose from the sea to connect North and South America millions of years ago, mammals could cross the bridge in both directions. But the result of this massive migration—a large proportion of mammals with North American origins in South America, but not the other way around—has long puzzled paleontologists. To explore the origins of this drastic asymmetry, researchers from the Smithsonian Tropical Research Institute (STRI), the Gothenburg Global Biodiversity Centre and collaborating institutions analyzed fossil data from the two continents.
Click here for original story, Disproportionate extinction of South American mammals when Americas collided evident today
Source: Phys.org