which two characteristics describe a good index fossil?\n□ a. being found in many regions\n■ b. having…

which two characteristics describe a good index fossil?\n□ a. being found in many regions\n■ b. having existed for a very long time\n□ c. being very rare\n■ d. having an unusual shape

which two characteristics describe a good index fossil?\n□ a. being found in many regions\n■ b. having existed for a very long time\n□ c. being very rare\n■ d. having an unusual shape

Answer

Brief Explanations:

A good index fossil is widespread (found in many regions) and has a short - lived existence in geological time. An unusual shape can also make it easily identifiable. Existing for a very long time is not a characteristic of a good index fossil as it makes it less useful for dating specific time periods. Being very rare also limits its use as an index fossil.

Answer:

A. Being found in many regions D. Having an unusual shape