First mammals appeared around

Options

A. 459 million years back
B. 220 million years back
C. 1600 million years back
D. 3800 million years back

Answer

**Step-by-Step Solution:**

1. **Identify the Timeframe**: The question asks about the appearance of the first mammals. We need to establish the timeframe in which mammals first appeared on Earth.

2. **Understand the Extinction of Dinosaurs**: The extinction of dinosaurs occurred at the end of the Cretaceous period, approximately 65 million years ago. This event marks a significant transition in Earth's biological history.

3. **Determine the Era of Mammals**: After the extinction of dinosaurs, the Cenozoic Era began, which is often referred to as the "Age of Mammals." This era is characterized by the rise and diversification of mammals.

4. **Establish the Appearance of First Mammals**: The first mammals are believed to have appeared during the late Triassic period, which is around 220 million years ago, before the dinosaurs went extinct.

5. **Conclusion**: Therefore, the first mammals appeared around 220 million years ago.

**Final Answer**: The first mammals appeared around 220 million years ago.

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