OBJECTIVE LIFE SCIENCE
DIVERSITY AMONG LIFE FORMS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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widespread geographically, long lifespan
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widespread geographically, short lifespan
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specific place, long lifespan
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specific place, short lifespan
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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.
Detailed explanation-2: -Ammonites, trilobites, and graptolites are often used as index fossils, as are various microfossils, or fossils of microscopic organisms. Fossils of animals that drifted in the upper layers of the ocean are particularly useful as index fossils, as they may be distributed all over the world.
Detailed explanation-3: -The best index fossils are common, easy-to-identify at species level, and have a broad distribution-otherwise the likelihood of finding and recognising one in the two sediments is low. Ammonites fit these demands well, and are the best-known fossils that have been widely used for this.