Input (grade 12): The Ordovician came to a close in a series of extinction events that, taken together, comprise the second largest of the five major extinction events in Earth's history in terms of percentage of genera that went extinct. The only larger one was the Permian-Triassic extinction event.
Output (grade 12): The Ordovician ended with a series of extinction events that, together amount to the second greatest extinction of the Phanerozoic.