It is thought that approximately 90% of plant species went extinct during the Carboniferous Period (~320-290 mya). Which of the following graphs represent the changes that likely occurred in carbon dioxide and oxygen levels? (The solid black line depicts CO₂ levels, the dashed line represents O₂ levels) The left side of the x-axis represents the time of the extinction event.

Question

Quizplus · Accepted Answer

During the Carboniferous Period, there was a significant amount of photosynthesis occurring by the abundant plant life. As these plant species went extinct, there would be a decrease in the amount of oxygen being produced and an increase in the amount of carbon dioxide being released into the atmosphere. Graph H shows this pattern, with a decrease in oxygen levels and an increase in carbon dioxide levels around the time of the extinction event. The other graphs do not show this pattern.

It Is Thought That Approximately 90% of Plant Species Went