Which of the following are poikilothermal animals with single occipital condyle and 12 pair of cranial nerves ?

Options

A. Aves
B. Reptiles
C. Mammals
D. Amphibia

Answer

To solve the question regarding poikilothermal animals with a single occipital condyle and 12 pairs of cranial nerves, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Poikilotherm**:
- Poikilothermic animals, also known as cold-blooded animals, cannot regulate their body temperature internally and depend on external environmental conditions to maintain their body temperature.

2. **Identify Occipital Condyle**:
- The occipital condyle is a protuberance on the undersurface of the occipital bone in the skull. Animals can have one or two occipital condyles.

3. **Cranial Nerves**:
- Cranial nerves are nerves that originate from the brain. The question specifies that we are looking for animals with 12 pairs of cranial nerves.

4. **Classify the Groups**:
- Among the animal groups, Aves (birds) and Mammals are homeothermic (warm-blooded) and can regulate their body temperature, so they do not fit the criteria of poikilotherms.
- Amphibians and reptiles are poikilothermic.

5. **Examine Amphibians and Reptiles**:
- Amphibians have two occipital condyles and 10 pairs of cranial nerves.
- Reptiles have a single occipital condyle and 12 pairs of cranial nerves.

6. **Conclusion**:
- Based on the characteristics outlined, reptiles are the only group that fits all three criteria: they are poikilothermic, have a single occipital condyle, and possess 12 pairs of cranial nerves.

### Final Answer:
The animals that are poikilothermal with a single occipital condyle and 12 pairs of cranial nerves are **Reptiles**.

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