Which of the following is not a character of Aves?

Options

A. The forelimbs are modified into wings
B. The hindlimbs generally have scales and the long bones are pneumatic
C. Skin is dry without glands except the oil gland at the base of the tail
D. They are oviparous and have external fertilisation

Answer

To determine which of the following is not a character of Aves, we will analyze each option provided:

1. **Forelimbs are modified into wings**:
- In birds (Aves), the forelimbs are indeed modified into wings, which is a characteristic feature that aids in flight.
- **Conclusion**: This statement is correct.

2. **Hind limbs generally have scales and the long bones are pneumatic**:
- Birds have scales on their hind limbs, and their long bones are pneumatic (hollow), which helps reduce body weight for flight.
- **Conclusion**: This statement is also correct.

3. **Skin is dry without glands except the oil gland at the base of the tail**:
- The skin of birds is generally dry and lacks many glands, with the exception of the oil gland located at the base of the tail, which helps in maintaining feather condition.
- **Conclusion**: This statement is correct as well.

4. **They are oviparous, i.e., they lay eggs and have internal fertilization**:
- Birds are indeed oviparous, laying eggs, but they typically have external fertilization (the male fertilizes the eggs outside the female's body).
- **Conclusion**: This statement is incorrect because while birds lay eggs, the fertilization is not internal in the typical sense.

Based on the analysis, the statement that is not a character of Aves is the fourth option: **"They are oviparous, i.e., they lay eggs and have internal fertilization."**