Disproportionate extinction of South American mammals when Americas collided evident today

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.

Their results, recently published in the journal Proceedings of the National Academy of Sciences (PNAS), show that the main reason there are more mammals of North American ancestry in South America than vice-versa was the disproportionate extinction of South American mammals during the Great American Biotic Interchange that followed the formation of the isthmus. This reduced the diversity of native mammals available to disperse northwards.

“This faunal exchange can be seen as a natural experiment: two continents, each with its own kind of animals were connected by a narrow land bridge, allowing massive migrations in both directions,” said Juan Carrillo, STRI fellow and lead author on the study at the National Museum of Natural History in Paris. “Our study shows how these migrations happened and that South American mammals had more extinctions. The effect of this exchange can be still seen today.”

Almost

Related posts:

This is a summary of what we’ve achieved and what there is still to do, through our Stories of Extraction project, enabled by the Activist Museum Award. The call is out for the second year of this…

We root for them because we can resonate with their pain. We watch, on the edge of our seats, because we see them use this pain to achieve a goal. We cheer for them.

Let me first clarify as people use the word ghost and spirit interchangeably but there really is a strong difference between them. Spirits are what we understand to be the souls of the deceased, with…