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A Brief History of Life


Origins homepage

Click on images to view larger versions, and click on highlighted terms to see glossary definitions.

Era Period Epoch Age Life Forms
Archeozoic Precambrian
Precambrian
  4,500-550 mya (millions of years ago) First single-celled organisms, simple plants, and invertebrate animals: algae, bacteria, jellyfish, flagellates, amoebas, worms, sponges
Paleozoic Cambrian
Cambrian
  550-505 mya First trilobites, forams, brachiopods, nautiloids, clams, snails, crustaceans, crinoids, gastropods, corals, protozoans
Ordovician
Ordovician
  505-438 mya First starfish, sea urchins, blastoids, eurypterids, bryozoa, scaphopods, jawless fish, echinoids
Silurian
Silurian
  438-408 mya First land plants, ferns, sharks, boney fish, scorpions
Devonian
Devonian
  408-360 mya First insects, tetrapods, ammonites, placoderms
Carboniferous
Carboniferous
Mississippian 360-325 mya First reptiles, spiders, amphibians
Pennsylvanian 325-286 mya First conifers, synapsids
Permian
Permian
  286-248 mya Heyday of synapsids, including pelycosaurs
Mesozoic Triassic
Triassic
  248-213 mya First turtles, cycads, lizards, dinosaurs, mammals
Jurassic
Jurassic
  213-145 mya First squids, frogs, birds, salamanders
Cretaceous
Cretaceous
  145-65 mya First flowering plants, snakes, modern fish, rise and fall of toothed birds, heyday of dinosaurs
Cenozoic Tertiary
Tertiary
Paleocene 65-55.5 mya Diversification of mammals
Eocene 55.5-33.7 mya First marine and large terrestrial animals, horses, whales, monkeys
Oligocene 33.7-23.8 mya First grasses, apes, anthropoids
Miocene 23.8-5.3 mya First hominids
Pliocene 5.3-1.8 mya First Australopithecines
Quaternary
Tertiary
Pleistocene 1.8 mya-8,000 ya Mammoths, mastodons, Neanderthals
Holocene 8,000 ya-present First modern human beings



Origins

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