Which one of the following characters is not typical of the class Mammalia

Options

A. Seven cervical vertebrae
B. Thecodont dentition
C. Ten pairs of cranial nerves
D. Alveolar lungs

Explanation

To solve the question "Which one of the following characters is not typical of the class Mammalia?", we will analyze each of the given options step by step.

### Step 1: Understand the Characteristics of Mammals
Mammals are a class of animals with specific characteristics that distinguish them from other classes. We need to identify which of the provided options does not fit these characteristics.

### Step 2: Analyze Each Option
1. **7 Cervical Vertebrae**:
- All mammals have 7 cervical vertebrae, regardless of their size. This is a typical characteristic of mammals.

2. **Thecodont Dentition**:
- Thecodont dentition refers to the structure of teeth where the roots are embedded in the jawbone. This is also a characteristic feature of mammals.

3. **10 Pairs of Cranial Nerves**:
- Mammals actually have 12 pairs of cranial nerves, not 10. This is the option that does not fit the typical characteristics of mammals.

4. **Alveolar Lungs**:
- Mammals possess alveolar lungs, which are characterized by small air sacs (alveoli) that facilitate gas exchange. This is a typical feature of mammals.

### Step 3: Conclusion
Based on the analysis, the character that is not typical of the class Mammalia is **10 pairs of cranial nerves**. Therefore, the correct answer is option 3.

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