On a second archeological dig scientists find several examples of the index fossil Pecten gibbous deposited in layers of rocks. One researcher, Researcher A, is excited because she believes that particular index fossil indicates that early human fossils could be found in the area. Another, Researcher B, disagrees, suggesting there may be dinosaur fossils in this particular rock strata. Comment on the suggestions of the two scientists.
A The index fossil, Pecten gibbous, would be found in rock layers from the quaternary period and dinosaurs had been on earth for several periods, so Researcher B is correct.
B The index fossil, Pecten gibbous, would be found in rock layers from the cenozoic era and that is the time of the rise of mammals, so Researcher A would be correct.
C The index fossil, Pecten gibbous, would be found in rock layers from the quaternary period. The researchers should expect to find fossils of both humans and dinosaurs in this same strata.
D The index fossil, Pecten gibbous, would be found in rock layers from the quaternary period, the time man appeared on Earth. Researcher A is correct.
