which of the following is the smallest taxonomic grounp of animals having a cranium , vertabral column , ventral heart , pulmonary respiration and two pairs of limbs

Options

A. Chordata
B. Gnathostomata
C. Vertebrata
D. Tetrapoda

Answer

To solve the question of which is the smallest taxonomic group of animals having a cranium, vertebral column, ventral heart, pulmonary respiration, and two pairs of limbs, we can analyze the options provided step by step.

### Step-by-Step Solution:

1. **Identify the Characteristics:**
- The group must have:
- A cranium (skull)
- A vertebral column (backbone)
- A ventral heart (heart located on the underside)
- Pulmonary respiration (breathing using lungs)
- Two pairs of limbs (four limbs in total)

2. **Evaluate the Options:**
- **Option 1: Caudata (or Prochordates)**
- These animals do not possess a well-developed cranium, limbs, vertebral column, or a ventral heart.
- **Conclusion:** This option is incorrect.

- **Option 2: Nathostomata**
- This group primarily includes fishes, which do not have limbs (they have fins instead).
- **Conclusion:** This option is also incorrect.

- **Option 3: Vertebrata**
- This group includes various sub-groups, such as Agnatha (jawless fishes), which do not have a well-developed cranium or limbs.
- **Conclusion:** This option is incorrect.

- **Option 4: Tetrapoda**
- Tetrapoda includes animals that have a well-developed cranium, a vertebral column, a ventral heart, pulmonary respiration, and two pairs of limbs (four limbs).
- **Conclusion:** This option meets all the criteria.

3. **Final Answer:**
- The smallest taxonomic group of animals having a cranium, vertebral column, ventral heart, pulmonary respiration, and two pairs of limbs is **Tetrapoda**.