What advantages did North American mammals have over South American mammals?

Question

What advantages did North American mammals have over South American mammals?

Answer 1

All the large mammals in South America became extinct. Because of its long isolation from the other continents, few large mammals migrated to South America. North America was connected to Eurasia for long period of time. Many species of large mammals migrated to North America. Biodiversity has helped the survival of large mammals in North America.

Answer 2

North American mammals grew fur to keep them warm during cold spells and that would enable them to survive longer.

Answer 3

Neither had advantage over the other. The two continents were separate during much of the animals evolution and each evolved as best suited to their particular environment.