When one hears the name "Beringia", we most often think the land bridge that formed as a result of a drop in sea levels during the Pleistocene, resulting in a connection between Alaska and Russia. But Beringia had been connecting East to West in a continuous cycle, the earliest so far being in the late Cretaceous, opening ceratopsians, troodontids and even tyrannosaurs from Asia to North America.
Nowadays, Beringia is submerged beneath sea level. As a result, North America has a different cast from Eurasia, the splits being listed as follows:
Telemetacarpal deer (whitetails, caribou, moose, deer that are more common in North America than in Eurasia) and plesiometacarpal deer (chitals, fallows, wapitis, reds, deer that are more common in Eurasia than in North America)
Peccaries and pigs
Hyenas and dogs
Old World porcupines (Hystricidae) and New World porcupines (Erethizontidae)
Pronghorns and antelopes (No, this is not a typo, as pronghorn aren't true antelopes)
Leopards and pumas/jaguars
American sparrows (Passerellidae) and Old World sparrows (Passeridae)
Condors and vultures
Pandas and raccoons
Now, in this speculative scenario, Beringia has been open for permanent business for at least five million years. Beringia would obviously homogenize the animals of the northern hemisphere, but from the list above, which side of each split would be more successful at colonizing both North America AND Eurasia at once?