In birds, the vertebrae are

Options

A. Amphicoelous
B. Acoelous
C. Heterocoelous
D. Ophisthocoelous

Answer

**Step-by-Step Solution:**

1. **Understanding Vertebrae Types**: Begin by identifying the different types of vertebrae mentioned in the question. The types include Amphicelous, Acoelous, Heterocelous, and Opisthocelous.

2. **Analyzing Amphicelous Vertebrae**: Amphicelous vertebrae are biconcave, meaning they have a concave shape on both sides. These vertebrae are typically found in reptiles.

3. **Analyzing Acoelous Vertebrae**: Acoelous vertebrae are flat on both sides of their centrum. These are found in mammals and are characterized by their flat structure.

4. **Analyzing Heterocelous Vertebrae**: Heterocelous vertebrae have one side that is concave and the other side that is either convex or flat. This type of vertebrae is specifically found in the neck region of birds.

5. **Analyzing Opisthocelous Vertebrae**: Opisthocelous vertebrae are flat on the anterior side and concave on the posterior side. These are typically found in salamanders, which belong to the reptile group.

6. **Conclusion**: Based on the analysis, the vertebrae found in birds are identified as Heterocelous vertebrae. Therefore, the correct answer to the question is Heterocelous.

**Final Answer**: In birds, the vertebrae are Heterocelous.

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