Question

Several fish species became extinct millions of years ago. The graphs provided below show the distribution of fossils of these fishes as they occur in several undisturbed layers of sedimentary rock observable in a cliff face. Respond to ALL 4 PARTS below: Explain why the distribution of the fossils in figure 1 support the hypothesis that the extinction of these species was a result of a sudden environmental change. Describe an environmental change that could have produced this kind of fossil distribution. Explain why the distribution of the fossils in figure 2 supports the hypothesis that the extinction of these species was a result of a gradual environmental change. Describe an environmental change that could produce this kind of fossil distribution.

Answer 1

1. Explain why the distribution of fossils in Figure 1 supports the hypothesis that the extinction of these species was the result of a sudden environmental change.
This hypothesis can be supported because all the fossils accumulate almost at the same age of the rock layer. That is, all the fossils died almost at the same time.

2. Describe an environmental change that could have produced this type of fossil distribution.
Good examples of sudden environmental changes are volcanoes. When a rash occurs, the whole environment suddenly changes for different reasons such as ash or lava, and all living things can die immediately or in a few years by the change in the ecosystem.

3. Explain why the distribution of fossils in Figure 2 supports the hypothesis that the extinction of these species was the result of a gradual environmental change.
This is because the fossils accumulate at different ages of the rock layer, that means, the species dying over time. The gradual descent of the fossils is observed.

4. Describe an environmental change that could produce this type of fossil distribution.
For example, if a climate change occurs - the temperature increases or decreases - it can cause the trees or plants to die and all the animals in the ecosystem also die when they have no food. But this process is sequential, so the change can take years, centuries or even millions of years.

I hope this can help you.