Suppose that Pangaea were reunited today. What macroevolutionary changes would you expect?. Earth & Marine Sciences

On land, the formation of Pangaea would likely result in increased continentality (greater climatic extremes). In the oceans, the reunion of the continental plates would result in a decrease in shallow waters along the margins of the plates. Ocean circulation would shut down and global climate would change drastically. These changes would likely result initially in large-scale extinctions as species unable to adapt to rapid and extreme changes disappeared. Biodiversity would decrease. Eventually it is possible, and even likely, that species that were able to adapt to the new conditions would radiate and biodiversity would increase.