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570-500 Milion years. Most life during the Cambrian Period were aquatic, with trilobites as the dominant life form.
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The Ordovician Period started at a major extinction event called the Cambrian–Ordovician extinction events. Trilobites and Brachiopods in particular were rich and diverse.
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Started when 60% of marine species wiped out by mass extinction. An evolutionary milestone during the Silurian was the appearance of jawed and bony fish.
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The first ray-finned and lobe-finned bony fish appeared. Placoderms began dominating almost every known aquatic environment. Primitive sharks became more numerous in the oceans
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Amphibians were the dominant land vertebrates, Arthropods were also very common. A small marine and terrestrial extinction occurred in the middle of the period.
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World at the time had a large supercontinent called Pangaea. Trilobites and a host of other marine groups became extinct. About 90% of insects at the start of the Permian were cockroach-like insects
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Therapsids and archosaurs were the chief terrestrial vertebrates. Seed plants came to dominate the terrestrial flora.
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Supercontinent Pangaea had begun rifting into two landmasses. Numerous turtles could be found in lakes and rivers. Large archosaurian reptiles remained dominant.
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Flowering plants spread during this period. Pterosaurs were common in the early and middle Cretaceous. Tyrannosaurus rex, one of the largest land predators of all time, lived during the late Cretaceous.
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The first hominids appeared in Africa. Tropical plant species gave way to deciduous ones and grasslands replaced many forests.
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Substantial glaciers advanced and retreated over much of North America and Europe. Giant mammals thrived in parts of North America and Eurasia. These mammals became extinct when the last Ice Age ended.
