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Biology Chapter 12
| Term | Definition |
|---|---|
| relative dating | estimate of the age of a fossil based on the location of fossils in strata |
| radiometric dating | technique that uses the natural decay rate of isotopes to calculate the age of material |
| isotope | form of an element that has the same number of protons but a different number of neutrons as another element |
| half-life | amount of time it takes for one of the isotope in a sample to decay into its product isotope |
| index fossil | fossil of an organism that existed during only specific spans of geologic time across large geographic areas |
| era | second largest unit of geologic time; lasting tens to hundreds of millions of years and consisting of two or more periods |
| period | unit of geologic time that lasts tens of millions of years and is associated with a particular type of rock system |
| nebula | rotating cloud of gas and dust |
| cyanobacteria | bacteria that can carry out photosynthesis |
| endosymbiosis | ecological relationship in which one organism lives within the body of another |
| primate | mammal with flexible hands and feet, forward-looking eyes, and enlarged brains relative to body size |
| prosimian | oldest primate group that includes mostly small, nocturnal primates such as lemurs |
| anthropoid | humanlike primate |
| hominid | primate group that includes orangutans, chimpanzees, gorillas, and humans, as well as their intermediate ancestors |
| bipedal | animal that walks on two legs |