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 can break down the information provided in the video transcript into a step-by-step solution.

### Step-by-Step Solution:

1. **Identify the Oldest Ancestors**:
- The oldest ancestors of mammals are the **synapsids**. These are primitive reptiles that are crucial in the evolutionary history leading to mammals.

2. **Next Group of Ancestors**:
- From the synapsids, the next group that evolved is the **pelicosaurs**. These are also considered primitive reptiles and are characterized by their distinct features.

3. **More Advanced Ancestors**:
- Following the pelicosaurs, the evolution led to more advanced mammal-like reptiles known as **therapsids**. These creatures exhibited traits that are more closely related to modern mammals.

4. **Final Stage - Mammals**:
- The final stage in this evolutionary lineage is the emergence of **mammals** from the therapsids. This marks the transition from reptilian ancestors to true mammals.

5. **Summarize the Sequence**:
- Therefore, the correct sequence of ancestors of mammals starting from the oldest is:
- **Synapsids → Pelicosaurs → Therapsids → Mammals**

### Final Answer:
The correct sequence of ancestors of mammals starting from the oldest is: **Synapsids → Pelicosaurs → Therapsids → Mammals**.