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Chapter 12

The History of Life

TermDefinition
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 half 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
geologic time scale time scale representing the history of Earth
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 last tens of millions of years and it associated with a particular type of rock system
epoch smallest unit of geologic time, lasting several million years
nebula rotating cloud of gas and dust
ribozyme RNA molecule that can catalyze specific chemical reactions
cyanobacteria bacteria that can carry out photosynthesis
endosymbiosis ecological relationship in which one organism lives within the boy of another
Paleozoic era of geologic time (from 544 to 248 million years ago) during which members of every major animal group alive today evolved
Cambrian explosion earliest part of the Paleozoic era, when a huge diversity of animal species evolved
Mesozoic era during which dinosaurs roamed Earth (from 248 million years ago to 65 million years ago)
Cenozoic geologic time period that began 65 million years ago and continues today
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 immediate ancestors
bipedal animal that walks on two legs
Created by: harolds21
 

 



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