The Volcanic Ring that Changed the World

PART 1: How evolution and plate tectonics have operated in concert to produce the major biotic patterns of the Earth / Adapted from "Here Be Dragons"

If I had to point to a single geological feature of the Earth that had the greatest biogeographical consequences on the post-dinosaur world, that is, on our entire global ecosystem as encountered today, I would choose the chain of seafloor spreading ridges that presently encircles Antarctica.  This little-known ring of cracks in the ocean bottom has dra…