The Lost Worlds of Planet Earth Ortelius hypothesized the idea that land masses may have been connected in the past, Alfred Wegener who hypothesized the idea of a super-continent Pangaea and continental drift despite the prevailing idea of flooded land-bridges at the time, and Bruce C. Heezen and Marie Tharp who discovered the Mid-Atlantic Ridge that supported the theory of plate tectonics. Tyson describes how the landmasses of the earth lay atop the mantle, which moves due to the motion and heat of the earth's outer and inner core. Tyson moves on to explain the asteroid impact that initiated the Cretaceous–Paleogene extinction event, leaving small mammals
Growing Up in the Universe happen in the real world - natural factors come into play which control the population numbers, meaning that only an elite group of organisms will actually become distant ancestors. To be in this elite group, the organism must "have what it takes" to survive and pass on their genes to offspring. The long chain of successful ancestors means that the probability of our existence is very small, and we are lucky to be alive. By turning down the lights and shining a small spotlight on a large ruler in front of him, Dawkins illustrates the darkness of the distant past