Final answer:
The mass extinction event at the end of the (B) Permian period was the largest in Earth's history, where intense volcanic activity is believed to have led to a climate warming that caused the extinction of over 96% of marine species and 70% of terrestrial species.
Step-by-step explanation:
At the end of the Permian period, over 96% of marine species and many terrestrial species became extinct, possibly because intense volcanic activity warmed Earth's climate. The end-Permian extinction, also known as the Great Permian Extinction, stands as the largest mass extinction event in Earth's history.
Known for its devastating effect on global biodiversity, it led to the loss of approximately 96 percent of all marine species and 70 percent of terrestrial species, including the trilobites. Factors such as extreme volcanism, resulting in a runaway global-warming event, increased atmospheric CO2, and oceanic anoxia, are believed to have contributed to the massive die-off. Terrestrial tetrapod diversity took an estimated 30 million years to recover after this cataclysmic event.