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'Prehistoric life' are the diverse organisms that have inhabited Earth from the origin of life about 3.8 billion years ago (b.y.a.) to the Historic period (about 3500 BC) when humans began to keep written records.
During the course of evolution, new forms of life developed and many other forms, such as the dinosaurs, became extinct. (See Timeline of evolution).
Prehistoric life evolved over this vast timespan from simple bacteria-like cells in the oceans to algae and protozoa, and ultimately to complex multicellular forms such as fungi, land plants, worms, molluscs, crustaceans, insects, and vertebrates.
In geologic terms, humans evolved very recently, only about 4 million years ago (m.y.a.). (See Geologic time scale).
Very few species of prehistoric life (such as the coelacanth) still exist today unchanged, tens of millions of years later, thereby making them living fossils. Yet other creatures, like sharks, have changed but a little over millions of years.
However, most life forms -- over 99 percent -- have become extinct, and so the only record of them ever existing that remains today are rock imprints, casts or other fossils.

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★ Ammonites -- once-common coiled mollusks ★ Corals -- now common as fossils ★ Dinosaurs ★ Evolution ★ Evolution, science of ★ Evolutionary history of life -- a more technical site ★ Forams (a.k.a. foraminifera) -- very useful tiny fossils ★ Fossils -- the remnants of prehistoric life ★ Fossil collecting ★ Fossil parks -- includes protected sites worldwide ★ History of evolutionary thought ★ History of invertebrate paleozoology ★ History of paleontology ★ Invertebrate paleontology -- covers most animal fossils ★ Lampshells (a.k.a. brachiopods) -- the ''most-common'' fossils ★ List of fossil sites ''(with a link directory)'' ★ List of notable fossils ★ Nautiloids -- mostly long-shelled, extinct cephalopods ★ Macrofossils -- of larger prehistoric animals and plants ★ Microfossils -- of smaller, tiny prehistoric life ★ Micropaleontology -- study of prehistoric microbes, etc.

★ Paleobiology -- study of fossils and biology ★ Paleobotany -- study of prehistoric plants ★ Paleoichnology -- studies traces of prehistoric life ★ Paleontology -- study of fossils and geology ★ Paleozoology -- study of prehistoric animals ★ Palynology -- study of fossil seeds & plant spores ★ Prehistoric amphibians ★ Prehistoric animals ★ Prehistoric birds ★ Prehistoric fish ★ Prehistoric insects ★ Prehistoric mammals ★ Prehistoric plants ★ Prehistoric reptiles ★ Sea scorpions (a.k.a. eurypterids) -- extinct marine carnivores ★ Sea lilies (a.k.a. crinoids) -- stems common as fossils ★ Stromatolites of colonial cyanobacteria -- the oldest "living fossil" ★ Taphonomy -- study of burial and fossilization of life ★ Trace fossils -- indirect traces of prehistoric life ★ Trilobites -- extinct, armored creatures ★ Vertebrate paleontology -- covers fishes and tetrapods

External links

★ PREHISTORICS ILLUSTRATED .com