Dry scaly skin, 3-chambered heart with partial septum.

Explanation

**Step-by-Step Solution:**

1. **Identify the Characteristics**: The question mentions two specific characteristics: dry scaly skin and a three-chambered heart with a partial septum.

2. **Relate Characteristics to Animal Groups**:
- Dry scaly skin is a key feature of reptiles. Reptiles have scales that protect their bodies and prevent water loss, which is essential for their survival in terrestrial environments.
- The three-chambered heart with a partial septum is also characteristic of reptiles. This type of heart structure allows for some separation of oxygenated and deoxygenated blood, improving the efficiency of blood circulation.

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