Which of the following is not an aerial adaptation in birds

Options

A. Pneumatic bone
B. Atrophied right ovary and oviduct
C. Sternum with keel
D. Crop and gizzard in the alimentary canal

Answer

To solve the question "Which of the following is not an aerial adaptation in birds?", we will analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Aerial Adaptations**:
- Aerial adaptations in birds are physical features that help them fly efficiently. These adaptations include lightweight bones, specialized reproductive systems, and modifications in the skeletal structure.

2. **Analyzing the Options**:
- **Option 1: Nomadic Bone**:
- Nomadic bones are lightweight and hollow, which reduce the overall weight of the bird, aiding in flight. Therefore, this is an aerial adaptation.

- **Option 2: Atrophied Right Ovary and Oviduct**:
- Birds typically have an atrophied right ovary and oviduct, which helps minimize body weight for flight. This is also an aerial adaptation.

- **Option 3: Sternum with Keel**:
- The sternum with a keel provides an attachment point for flight muscles, enhancing a bird's ability to fly. This is an aerial adaptation as well.

- **Option 4: Crop and Gizzard in the Alimentary Canal**:
- The crop and gizzard are parts of the digestive system. They are not related to flight but rather to the processing of food. Therefore, this option does not represent an aerial adaptation.

3. **Conclusion**:
- The correct answer is **Option 4: Crop and gizzard in the alimentary canal**, as it is not an aerial adaptation in birds.

### Final Answer:
**Option 4: Crop and gizzard in the alimentary canal** is not an aerial adaptation in birds.

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