19

Question

The diagram below represents a series of rock layers. Each different type of shape shown in the layers represents a fossil of a different species. For example, the yellow triangles represent one species while the green squares represent another. The labels on the right side indicate the geologic period during which each layer was formed.

At which point did a catastrophe that drastically changed the nonliving factors of this region most likely occur?
A.
at the end of the Triassic period
B.
at the beginning of the Cretaceous period
C.
at the end of the Jurassic period
D.
at the beginning of the Triassic period

Answer 1

To determine when a catastrophe that drastically changed the nonliving factors of the region most likely occurred, we typically look for significant changes in the fossil record between rock layers, as these would indicate mass extinctions or other major geological events.

1. At the end of the Triassic period (A) - This period saw one of the largest mass extinctions which may have profoundly affected life.
2. At the beginning of the Cretaceous period (B) - The start of this period did not coincide with a major extinction event.
3. At the end of the Jurassic period (C) - This period did witness significant evolutionary developments but not a major extinction event.
4. At the beginning of the Triassic period (D) - This marked the recovery from a mass extinction event but is not likely when a new catastrophe occurred.

Considering these points, the best choice would be A. at the end of the Triassic period, as it represents a significant geological and ecological reset due to mass extinction, which would have drastically changed nonliving factors in the region.