Which vertebrates evolved into the first amphibians?

Options

A. Jawless fishes
B. Lobefins
C. Salamanders
D. Ichthyosaurus

Answer

**Step-by-Step Text Solution:**

1. **Identify the Time Period**: The first amphibians are believed to have evolved during the Devonian period, approximately 370 million years ago.

2. **Understand the Characteristics of Early Amphibians**: The first amphibians had specific adaptations that allowed them to transition from water to land. These adaptations included the development of lungs and bony limb fins.

3. **Determine the Ancestral Group**: The vertebrates that evolved into the first amphibians are known as lobe-finned fishes. These fishes possessed the necessary features, such as lungs and bony fins, which made them suitable for life on land.

4. **Eliminate Incorrect Options**:
- Jawless fishes are primarily aquatic and do not have the adaptations required for terrestrial life.
- Salamanders are modern amphibians and not the ancestors of the first amphibians.
- Ichthyosaurus is a marine reptile and not directly related to the evolution of amphibians.

5. **Conclusion**: Based on the evidence, the vertebrates that evolved into the first amphibians are the lobe-finned fishes.

**Final Answer**: Lobe-finned fishes.

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