Question

In which one of the given mass extinction events, global cooling that resulted in glaciation and lowering of sea level, is considered as the major cause of extinction for more than 50% of marine fauna?

• A. Cretaceous – Paleogene
• B. Permian – Triassic
• C. Ordovician – Silurian
• D. Holocene

Hint:

Glaciation-driven extinctions are associated with the Ordovician–Silurian boundary. In contrast, volcanic activity is the primary driver for Permian–Triassic and asteroid impact for Cretaceous–Paleogene.

Answer 1

The Correct Option is C

Step 1: Recall major mass extinction events.
- Cretaceous–Paleogene (K–Pg, 66 Ma): Caused by asteroid impact and volcanism (Deccan traps). - Permian–Triassic (252 Ma): Largest extinction, linked to Siberian Traps volcanism, ocean anoxia, methane release. - Ordovician–Silurian (445 Ma): Caused mainly by global cooling, Gondwana glaciation, and associated sea-level fall. This event wiped out more than 50% of marine fauna. - Holocene (ongoing): Linked to human activities, not glaciation.

Step 2: Identify correct extinction.
Only the Ordovician–Silurian event was directly caused by global cooling, glaciation, and sea-level fall.

Final Answer:
\[ \boxed{\text{Ordovician – Silurian}} \]