Term | Definition |
Fossil | preserved from a past geologic age |
Relative dating | the arrangement of artifacts or events in a sequence relative to one another but without ties calendrically measured time; the arrangement of artifacts in a typological sequence or seriation |
Radiometric dating | any method of determining the age of earth materials or objects of organic origin based on measurement of either short-lived radioactive elements or the amount of a long-lived radioactive element plus its decay product. |
Isotope | any of two or more forms of a chemical element, having the same number of protons in the nucleus, or the same atomic number, but having different numbers of neutrons in the nucleus, or different atomic weights. |
Half-life | the time required for one half the atoms of a given amount of a radioactive substance to disintegrate. |
Index fossil | a widely distributed fossil, of narrow range in time, regarded as characteristic of a given geological formation, used especially in determining the age of related formations. |
Era | is a time of time marked by character, events, changes on earth, etc. Usually a mass extinction occurs. (Ex: The Ice Age, Dinosaurs, etc.) |
Period | a rather large interval of time that is meaningful in the life of a person, in history, etc., because of its particular characteristics |
Epoch | a particular period of time marked by distinctive features, events, etc. |
Ribozymes | are RNA molecules that are capable of catalyzing specific biochemical reactions, similar to the action of protein enzymes. |
Cyanobacteria | is a phylum of bacteria that obtain their energy through photosynthesis |
Endosymbiosis | symbiosis in which one symbiont lives within the body of the other. |
Cambrian explosion | The rapid diversification of multicellular animal life that took place around the beginning of the Cambrian Period. It resulted in the appearance of almost all modern animal phyla. |