How many mya, the jawless fish probably evolved?

Options

A. 320
B. 350
C. 400
D. 500

Explanation

To determine how many million years ago (mya) jawless fish (Agnatha) probably evolved, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Period of Evolution**:
- Jawless fish are classified under the group Agnatha. To find out when they first appeared, we need to look at the geological time scale.

2. **Locate the Ordovician Period**:
- The Ordovician period is a significant geological time frame that occurred after the Cambrian period. It is known for the diversification of marine life.

3. **Determine the Time Frame**:
- According to paleontological evidence, jawless fish first appeared in the Ordovician period, which is estimated to be around 400 million years ago.

4. **Conclusion**:
- Therefore, jawless fish probably evolved approximately **400 million years ago**.

### Final Answer:
Jawless fish (Agnatha) probably evolved around **400 million years ago**.

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