I just learned this today. the answer is Pangea.245 million years ago.
The Columbian exchange was the arrival of new species in the Old and the New Worlds. Among the many species that arrived in the New World were the bacteria and viruses that were causing many illnesses but to which the Old World people were immune. The Native Americans were not immune so many of them, by some estimates even 90 %, died.
Answer:
usually occurs in adults ,not children
