Which geological event allowed large placental carnivores to cross from North to South America?

Answer

The geological formation of the Isthmus of Panama

The terror birds' reign ended when the geological formation of the Isthmus of Panama connected North and South America, allowing for the Great American Interchange.

Which geological event allowed large placental carnivores to cross from North to South America?
birdPredatorextinctfossilterror bird