Colonisation of the Land

Why plants and insects colonized land much faster than vertebrates remains unclear. However, an increasing number of fossils are being found that represent transitional forms in this process. A particularly interesting question is how limbs evolved from the fins of fish. Many theories have been proposed to explain the origin of various limb bones, as well as the development of the five fingers and toes. This remains an active area of research.

Recently, the protective ozone layer was in significant danger. Human-produced CFC gases had begun to destroy the ozone layer. If this had not been stopped, life on land would have become nearly impossible within a few decades.