Trilobites were animals that lived in the ocean between 520 million and 540 million years ago. A trilobite fossil can be used as
an index fossil. What can a scientist learn from a trilobite fossil found in a layer of rock? A. That no other types of fossils will be found in the area
B. The temperature of the trilobite when it became a fossil
C. The age of the layer of rock the trilobite fossil was found in
D. That the area near the fossil was always dry land
