Peter D. Ward, OUT OF THIN AIR
Out of Thin Air: Dinosaurs, Birds, And Earth's Ancient Atmosphere by Peter D. Ward
My rating: 5 of 5 stars
With high levels of atmospheric oxygen, animals can grow very large, and do so because it protects them from predators. When oxygen levels drop, extinctions occur, and numbers of organisms of a given, surviving species drop, but body-plans proliferate as species strive to adapt. More than any other required resources, oxygen is absolutely necessary for the survival of animals, their ability to meet the exigencies of survival, and their ability to reproduce successfully, and it isn't at all surprising that as atmospheric oxygen levels have fluctuated over geological time, evolution has followed suit, mass extinctions and certain evolutionary radiations occurring as oxygen dropped, and more evolutionary radiations occurring once oxygen began to rise. During the Permian-Triassic mass extinction and again at the end of the Triassic Period of the Mesozoic Era, oxygen levels fell so low that animals couldn't manage to climb low hills less than a hundred feet high, running into the same problem that climbers of Mt. Everest did: lethal lack of oxygen in the air they breathed. Animals were locked into relatively small habitats by that the way animals today are coralled their habitats by high mountain ranges, wide lakes or inland seas, and other geographical barriers. As a result, each group of animals barriered from others by low oxygen levels began to evolve away from formerly identical groups of animals in other barriered habitats, thereby giving rise to new species, then whole new genuses, families, orders, and classes of animals in the process.
An elegant and beautifully illustrated presentation of a new theory of the things driving evolution, Out of Thin Air should be in the private library of everyone with a serious interest in the biological sciences, as well as in every public library and bookstore.
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