Standard and Benchmark Assessed:
Standard: Life Sciences
Benchmark: D. Explain how extinction of a species occurs when the environment changes and its adaptive characteristics are insufficient to allow survival (as seen in evidence of the fossil record).
Multiple Choice Question:
Use the diagram showing a cross section of a hill and the information below to answer question 35.
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.
35. The fossil evidence supports which hypothesis about the extinction of the older reptile species?
A. The older reptile species went extinct because sea levels rose and flooded its habitat.
B. The older reptile species went extinct because a predator was introduced into the environment.
C. The older reptile species went extinct because it could not compete with the younger reptile species.
D. The older reptile species went extinct because a volcanic eruption caused the environment to change.
Source: Ohio Department of Education July 05

Commentary:
This multiple choice question asks students to use the fossil record to identify how a particular species of reptile may have become extinct. Students must recall that organisms interact with their environments in order to survive and that species are adapted to live in particular environments. Students should recognize that species may become extinct when they cannot adapt to changes in their environments. Students need to understand the basic environmental needs of different organisms and recognize how this information could be represented in the rock record. For example, the layer of volcanic ash shown in the cross-section of the diagram suggests the eruption of a volcano that significantly changed the environment. In order for students to correctly answer this question, they also must recall the Law of Superposition and how it is applied to determine the relative age of rock layers in a cross section. Answer choice
D is correct because the older reptile fossil does not appear in the younger rock layers, which implies that this species went extinct before, or shortly after, the volcanic eruption. Answer choice A is incorrect because there is not enough information shown in the fossil record to support the conclusion that the older reptile species went extinct because sea levels rose and flooded its habitat. Answer choice B is incorrect because there is no evidence in the fossil record to suggest that a predator was responsible for the extinction of the older reptile species.
Answer choice C is incorrect because the fossil record does not show that the two reptile species lived at the same time so there is no evidence that they were in direct competition for resources.
This question is classified as Communicating Understanding / Analyzing Science Information because the task requires students to make valid inferences on the basis of scientific evidence
(fossil record). Students must bring together their knowledge of life and Earth sciences to determine the likely cause of extinction of a species.
Performance Data:
The percent of public school students selecting answer choice D for question 35 on the May
2007 Ohio Grade 8 Achievement Test for Science was 66%.
Keywords: fossil, ecosystem, extinction
Source: Ohio Department of Education July 05