Question

a student finds a fossil of a tropical aquatic shellfish in a sedimentary rock layer while visiting the desert in the united states. which can the student infer from the fossil discovery? a. the desert was once covered with water and much closer to the equator. b. the desert has always been dry and was once much closer to the equator. c. the desert has always been dry and has always been in the same location on earth. d. the desert has always been dry and much closer to one of the poles.

Explanation:

A tropical aquatic shellfish fossil implies a past aquatic environment. Tropical climates are typically near the equator. So, the area (desert) must have been covered by water (for the shellfish) and closer to the equator (for the tropical aspect) in the past.

Answer:

A. The desert was once covered with water and much closer to the equator.