The CORRECT Sequence of ancestors of mammals starting from the oldest is :

Options

A. Sauropsida `to` Pelycosaurs `to` Therapsida
B. Synapsids `to` Pelycosaurs `to` Therapsida
C. Synapsids `to` Therapsida `to` Pelycosaurs
D. Pelycosaurs `to` Therapsida `to` Synapsids

Answer

To determine the correct sequence of ancestors of mammals starting from the oldest, we need to analyze the evolutionary timeline of these groups. Here’s a step-by-step breakdown:

### Step 1: Identify the Ancestors
The ancestors mentioned in the question are:
1. Synapsids
2. Pelycosaurs
3. Therapsids
4. Sauropsids

### Step 2: Establish the Timeline
Next, we need to establish when each of these groups evolved:
- **Synapsids**: Evolved approximately 312 million years ago.
- **Pelycosaurs**: Evolved approximately 300 million years ago.
- **Therapsids**: Evolved approximately 275 million years ago.
- **Sauropsids**: Evolved approximately 66 million years ago.

### Step 3: Arrange the Ancestors by Age
Now, we will arrange these ancestors in order of their evolution from oldest to most recent:
1. **Synapsids** (312 million years ago)
2. **Pelycosaurs** (300 million years ago)
3. **Therapsids** (275 million years ago)
4. **Sauropsids** (66 million years ago)

### Step 4: Conclusion
The correct sequence of ancestors of mammals starting from the oldest is:
1. Synapsids
2. Pelycosaurs
3. Therapsids
4. Sauropsids

### Final Answer
The correct sequence is: **Synapsids → Pelycosaurs → Therapsids → Sauropsids**

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