Which of these is the correct evolutionary line of mammals ?

Options

A. Sauropsids `rarr` Synapsids `rarr` Therapsids `rarr` Mammals
B. Sauropsids `rarr` Suropsids `rarr` Therapsids `rarr` Mammals
C. Sauropsids `rarr` Therapsids `rarr` Mammals
D. Suropsids `rarr` Therapsids `rarr` Mammals

Answer

To determine the correct evolutionary line of mammals, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Ancestors of Mammals**:
- Mammals are derived from a group of reptiles known as synapsids.

2. **Understand the Classification**:
- The evolutionary line begins with tetrapods, which are four-limbed vertebrates.
- From tetrapods, we have amphibians and amniotes.

3. **Differentiate Between Sauropsids and Synapsids**:
- Sauropsids are the lineage that leads to reptiles and birds, while synapsids lead to mammals.

4. **Trace the Evolutionary Line**:
- The evolutionary sequence is as follows:
- **Tetrapods** → **Amphibians** → **Amniotes** → **Sauropsids** and **Synapsids**.
- From synapsids, we further classify into:
- **Pelycosaurs** (early synapsids)
- **Therapsids** (more advanced synapsids)
- **Cynodonts** (the group that directly leads to mammals)
- Finally, we arrive at **Mammals**.

5. **Summarize the Correct Line**:
- The correct evolutionary line of mammals is:
- **Sauropsids** → **Synapsids** → **Therapsids** → **Mammals**.

6. **Select the Correct Option**:
- Based on the options provided, the correct evolutionary line of mammals is the one that follows the order: **Sauropsids → Synapsids → Therapsids → Mammals**.