Final answer:
The mass extinction at the end of the Permian was likely caused by extended and widespread volcanic activity, resulting in a runaway global warming event. This extinction event dramatically altered Earth's biodiversity makeup and the course of evolution.
Step-by-step explanation:
The mass extinction at the end of the Permian was likely caused by extended and widespread volcanic activity, resulting in a runaway global warming event. The volcanic activity led to changes in ocean chemistry, making the oceans largely anoxic and suffocating marine life. This extinction event dramatically altered Earth's biodiversity makeup and the course of evolution.