2. Trilobites are useful as index fossils, because each species existed for a (1 point)
long period of time over a wide geographic range.
long period of time over a small geographic range.
short period of time over a wide geographic range.
short period of time over a small geographic range.
3. How would you date a sample of rock that you suspect as being one of the earliest on Earth? (1 point)
Use a radioactive isotope with a short half-life.
Use a radioactive isotope with a long half-life.
Use an index fossil.
Use a microfossil.

Question

2.   Trilobites are useful as index fossils, because each species existed for a  (1 point)
long period of time over a wide geographic range.
long period of time over a small geographic range.
short period of time over a wide geographic range.
short period of time over a small geographic range.
3.   How would you date a sample of rock that you suspect as being one of the earliest on Earth?  (1 point)
Use a radioactive isotope with a short half-life.
Use a radioactive isotope with a long half-life.
Use an index fossil.
Use a microfossil.

anonymous · Answer

http://answers.yahoo.com/question/index?qid=20110425192528AAfNfpJ http://openstudy.com/study#/updates/51366c09e4b093a1d94a7e24 the second link may not help but its the best i could do :D

anonymous · Answer

haha ok thanks! (: