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 Immense, shallow oceans covered much of the planet during the Cambrian and Ordovician periods. After three billion years of evolution, Earth witnessed an explosion of life.
Arthropods, sponges, mollusks, and more populated these shallow seas. The number of animal species eventually tripled—and all the major animal groups we are familiar with first appeared during this time.
To find out more about this world of water, select from the following:
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Basic Overview
Get the full scoop on the ocean life that evolved during this time, and learn about the mass extinction that wiped out nearly 70% of these aquatic species at the end of the Ordovician Period.
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Image Gallery
View fossils of ancient ocean life and check out some of the curious creatures that lived only during the Cambrian Period.
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Evolutionary Essentials
Discover two major steps in evolution—the development of skeletons and the emergence of animals with backbones—that paved the way for animal life as we know it today.
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Continue to Basic Overview. >>
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