Final answer:
The Late Permian mass extinction, the largest in Earth's history, was primarily caused by massive volcanic eruptions in Siberia. These eruptions led to severe environmental changes, such as climate warming and altered ocean chemistry, resulting in a significant loss of biodiversity.
Step-by-step explanation:
The primary cause for the largest mass extinction, which is the Late Permian mass extinction, is believed to be related to massive volcanic eruptions in Siberia. These eruptions led to the outpouring of basaltic lava, contributing to the warming of Earth's climate and changes in ocean chemistry.
The Late Permian mass extinction event had such a significant impact on the history of life on Earth that it defines the boundary between the Paleozoic and Mesozoic eras. Other causes of mass extinctions throughout Earth's history have included meteorite impacts, such as the one that ended the reign of the dinosaurs approximately 65 million years ago, as well as periods of glaciation, warming, and possibly gamma-ray bursts from supernovae.