The lower jaw in mammals is made up of
(a) Maxilla
(b) Dentary
(c) Mandible
(d) Ethmoid

Options

A. Mexilla
B. Dentary
C. Mendible
D. Ethmoid

Answer

To determine what the lower jaw in mammals is made up of, we can analyze the options provided:

1. **Understanding the Question**: The question asks specifically about the composition of the lower jaw in mammals.

2. **Analyzing the Options**:
- **(a) Maxilla**: This bone is part of the upper jaw and does not contribute to the lower jaw.
- **(b) Dentary**: This is a term that refers to the bone that forms the lower jaw in mammals.
- **(c) Mandible**: While this term is often used interchangeably with the lower jaw, it is more commonly associated with the entire lower jaw structure in some contexts, but it is not the specific name of the bone.
- **(d) Ethmoid**: This bone is located in the skull and is not related to the jaw structure.

3. **Identifying the Correct Answer**: The lower jaw in mammals is primarily made up of the **dentary** bone. This bone is a single structure that forms the lower jaw and is crucial for functions such as chewing.

4. **Conclusion**: Therefore, the correct answer is **(b) Dentary**.