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| Charles Darwin-- | scientist who studied nature and developed his theory of evolution based upon natural selection. |
| adaptation | an inherited characteristic that helps an organism survive and reproduce in its environment |
| species | a group of organisms that are closely related and can mate to produce fertile offspring |
| evolution | process in which inherited characteristics within a population change over generations such that new species sometimes arise |
| fossil | trace or remains of an organism that lived long ago |
| fossil record | history of life in the geologic past as indicated by the traces or remains of living things |
| relative dating | determining whether an event or object is older or younger than other events or objects |
| selective breeding | human practice of breeding animals or plants that have certain desired traits |
| natural selection | process by which individuals that are better adapted to their environment survive and reproduce more successfully that less well adapted individuals do |
| absolute dating | any method of measuring the age of an event or object in years |
| speciation | formation of new species as a result of evolution |
| paleontology | scientific study of fossils |
| geologic time scale | standard method used to divide Earth's long history into manageable parts |
| extinction | the death of every member of a species |
| Precambrian time | the time span from the formation of the Earth 4.6 billion years ago to 542 million years ago |
| Paleozoic Era | means “ancient life”, it is the time span from about 542 million years ago to about 251 million years ago, fish first appeared |
| Mesozoic Era | means “middle life”, it is the time from about 251 million years ago to about 65 million years ago, known as the Age of Reptiles |
| Cenozoic Era | means “recent life”, it is the time from about 65 million years ago to the present time, known as the Age of Mammals |
| superposition | principle that states that younger rocks lie above older rocks if the layers have not been disturbed |
| sedimentary rock | forms from compressed or cemented layers of sediment |
| plate tectonics | theory that explains how large pieces of Earth's outermost layer move and change shape |
