4. Certain fossils can also be useful for dating rocks. Index fossils represent organisms that lived a short amount of time (in a geological sense) and covered a wide geographic area. For example,...

Extracted text: 4. Certain fossils can also be useful for dating rocks. Index fossils represent organisms that lived a short amount of time (in a geological sense) and covered a wide geographic area. For example, suppose a sedimentary rock contains two different index fossils: A and B. Suppose that, based on paleontological studies, Species A lived from 4-7 million years ago, and Species B lived from 3-5 million years ago. Therefore, both species lived in the overlapping, 4-5 million year old time frame, and we assign that age to the rock. The following diagram shows age ranges, in millions of years ago (Ma), for different types of clams found in a rock. Use the method outlined above to determine an age range for the rock. Hint: In what time interval did all five clams live? What would be the estimated age range if M. subhercynius was not present in the rock? Ma 92.0 92.2 92.4 92.6 92.8 93.0 93.2 Inoceramid clams in the genus Mytiloides 93.4 M. hattiru M. kossmati M. columbiarus M. subhercynius M. labiatus