ANIMAL BEHAVIOR
SOCIAL BEHAVIOR
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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long period over a wide geographic range
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long period over a small geographic range
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short period over a wide geographic range
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short period over a small geographic range
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Detailed explanation-1: -A useful index fossil must be distinctive or easily recognizable, abundant, and have a wide geographic distribution and a short range through time. Index fossils are the basis for defining boundaries in the geologic time scale and for the correlation of strata .
Detailed explanation-2: -Why are the best index fossils from species that only existed for a short period of time? Because once they were very common they disappeared after the mass extinction event.
Detailed explanation-3: -Index fossils are used to define geological periods. These fossils can be defined as “commonly found, widely distributed fossils that are limited in time span.” If one finds an index fossil in a given layer, then one has bounds on the age of the layer. Using index fossils, the geological periods are defined.
Detailed explanation-4: -Index fossils of organisms have two important characteristics. First, they must have been widely distributed around the world. Second, they must have only existed for relatively short periods of geologic time before becoming extinct.
Detailed explanation-5: -Where is an index fossil found? An index fossil is typically preserved in sedimentary rock layers.