Scientists see three layers of rock exposed on the side of a hill. The bottom layer is sandstone with fossils of

a certain species of reptile found only in this geographic location. The middle layer is volcanic ash. The top
layer is mudstone (shale) with fossils of a different species of reptile.

The fossil evidence supports which hypothesis about the extinction of the older reptile species?

The older reptile species went extinct because sea levels rose and flooded its habitat.
The older reptile species went extinct because a predator was introduced into the environment.
The older reptile species went extinct because it could not compete with the younger reptile species.
The older reptile species went extinct because a volcanic eruption caused the environment to change.

1 answer

Based on the evidence presented — three layers of rock with distinct fossils — the most supportive hypothesis regarding the extinction of the older reptile species is:

The older reptile species went extinct because a volcanic eruption caused the environment to change.

This conclusion can be drawn from the presence of the volcanic ash in the middle layer. A volcanic eruption could have caused significant environmental changes, affecting the habitat of the older reptile species, potentially leading to its extinction. The introduction of ash could have altered the ecosystem’s flora and fauna, impacting the survival of the older species.

The other hypotheses, while plausible in different contexts, do not directly connect to the evidence of volcanic ash in this specific scenario.