Directions: Select the correct diagram. The diagrams below represent the fossils of shellfish in four hypothetical cross sections of a canyon. The top layers are the
youngest layers, and the bottom layers are the oldest
Which cross section could be used as evidence that, over time, a circular shellfish descended from a hexagonal shellfish?
1
2
3

The answer is number 4

Explanation:

Cross section 4 contains evidence that a transition from a hexagonal shellfish to a more a rectangular shellfish and then to a circular shellfish may have occurred. These changes would have been gradual, as shown by the position of the fossils in each layer of the canyon.

Although the evidence provided by cross section 4 is strong, more research would be needed to prove a connection among the shellfish in the canyon, such as morphological or

currents is the correct answer.