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Timescale of Earth
A. Paleozoic Era
- Precambrian Period = 4.6 billion years ago, lasted 4 billion years = algae and bacteria in warm waters
- Cambrian Period = 570 million years ago, lasted 70 million years = all life in seas, invertebrates begin (no backbone)
- Ordovician Period = 500 million years ago, lasted 60 million years = corals, first vertebrates, all life is in seas
- Silurian Period = 440 million years ago, lasted 45 million years = jawed fishes, first land plants, seaweed is abundant
- Devonian Period = 395 million years ago, lasted 50 million years = many fish, ancestors of modern fish evolve, first amphibians
- Carboniferous Period = 345 million years ago, lasted 65 million years = reptiles, insects and ferns appear
- Permian Period = 280 million years ago, lasted 55 million years = modern insects, much sea and freshwater life
B. Mesozoic Era
- Triassic Period = 225 million years ago, lasted 30 million years = many deserts, first mammals, many reptiles, early dinosaurs
- Jurassic Era = 195 million years ago, lasted 60 million years = first birds, many reptiles, many coniferous forests
- Cretaceous Period = 135 million years ago, lasted 70 million years = fishes evolve, many mammals and birds, reptiles dominate, flowering plants appear
C. Cenozoic Era
- Tertiary Period = 65 million years ago, lasted 63 million years = Flowering plants are numerous, whales adjust to marine life, Primates and hoofed mammals appear, teleost fish are dominant
- Quaternary Period = 2 million years ago, lasted to today = Modern man develops, marine life becomes what it is today
Sources:
"SeaLife" A Complete Guide to the Marine Environment, edited by Geoffrey Waller, Principal Contributors - Marc Dando and Michael Burchett "World Book Encyclopedia" by World Book, Inc. 1990
Internet Resources:
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