Any notable animals or plants that could be found in both America and the rest of the world before the discovery of The Americas? Or were the two so separate that no common species could be found?
Say for example, grass is found nearly everywhere in the world (not everywhere, looking at you Greenland), but even grass is divided into different types, and the common types were diffused thanks to, you guessed it, the Columbian Exchange.
Another example I can think of are coconuts, which, thanks to their buoyancy, managed to float their way to the New World some time ago, but I'm guessing that that is more of an anomaly than a good proof of shared species.
Aside from this, I have a hard time thinking of a species native to both sides of the pond, at least ones not brought back and forth after the 15th Century.
EDIT: As I see a couple of answers, I wonder, how did these species manage to live in/arrive to both continents?
Source: reddit post