Pneumatic bones, four chambered heart and feathers occur in
(a) Cyclostomata
(b) Aves
(c) Mammalia
(d) Reptilia

Options

A. Cyclotomata
B. Aves
C. mammalia
D. Reptilia

Answer

To solve the question regarding which group of animals possesses pneumatic bones, a four-chambered heart, and feathers, we will analyze each option step by step.

### Step 1: Understand the Terms
- **Pneumatic Bones**: These are bones that are hollow and contain air spaces, which help reduce body weight and are adaptations for flight.
- **Four-Chambered Heart**: This type of heart has two atria and two ventricles, allowing for efficient separation of oxygenated and deoxygenated blood.
- **Feathers**: These are unique to birds and are essential for flight, insulation, and display.

### Step 2: Analyze Each Option
- **Option (a) Cyclostomata**:
- Cyclostomata refers to jawless fishes like lampreys and hagfish.
- They do not have pneumatic bones, a four-chambered heart, or feathers.
- **Conclusion**: This option is incorrect.

- **Option (b) Aves**:
- Aves refers to birds.
- Birds have pneumatic bones, a four-chambered heart, and feathers.
- These features are adaptations that facilitate flight.
- **Conclusion**: This option is correct.

- **Option (c) Mammalia**:
- Mammals have solid bones (not pneumatic), a four-chambered heart, but do not possess feathers.
- **Conclusion**: This option is incorrect.

- **Option (d) Reptilia**:
- Reptiles generally have solid bones and a three-chambered heart (with some exceptions like crocodiles which have a four-chambered heart).
- They do not have feathers.
- **Conclusion**: This option is incorrect.

### Final Answer
Based on the analysis, the correct answer is **(b) Aves**.

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