Which is not aerial adaptation of Birds

Options

A. Single ovary
B. Pneumatic bone
C. Gizzard
D. Keeled sternum

Answer

To determine which option is not an aerial adaptation of birds, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Aerial Adaptations**: Aerial adaptations are features that help birds to fly efficiently. These adaptations generally focus on reducing body weight and enhancing flight capability.

2. **Analyzing the Options**:
- **Single Ovary**: Birds typically have a single ovary (monodelphic condition) which reduces body weight, aiding in flight. Thus, this is an aerial adaptation.
- **Pneumatic Bones**: These are hollow bones that reduce weight without sacrificing strength, making them beneficial for flight. Therefore, this is also an aerial adaptation.
- **Gizzard**: The gizzard is a muscular part of the digestive system that grinds food. Birds do have a gizzard, but it is not related to flight or aerial adaptation. Thus, this is not an aerial adaptation.
- **Keeled Sternum**: The keeled sternum provides an attachment point for flight muscles, which is crucial for the mechanics of flying. Hence, this is an aerial adaptation.

3. **Conclusion**: Among the options, the gizzard is the only feature that does not contribute to the aerial adaptations of birds.

### Final Answer:
The option that is not an aerial adaptation of birds is **Gizzard**.

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