Which of the following reptiles is the most current ancestor of modern mammals ?

Options

A. Therapsid
B. Plecosaurs
C. Sauropsids
D. Synapsid

Answer

To determine which reptile is the most current ancestor of modern mammals, we can analyze the options provided step by step.

### Step 1: Understand the question
The question asks for the reptile that is the most current ancestor of modern mammals. This requires knowledge of evolutionary biology and the lineage of mammals.

### Step 2: Analyze the options
1. **Therapsid**: This group of reptiles is known to be the ancestors of mammals. They are part of the synapsid lineage, which eventually led to the evolution of mammals.

2. **Plecosaurus**: This is a type of marine reptile, often considered a "mammal-like reptile," but it is not directly related to the lineage that led to modern mammals.

3. **Sauropsid**: This group includes modern reptiles and birds. It does not represent a direct lineage to mammals, as it is more of a broader category that does not include the ancestors of mammals.

4. **Synapsid**: While synapsids include mammals and their ancestors, they are not reptiles themselves. They represent a larger group that includes therapsids.

### Step 3: Identify the correct answer
Based on the analysis, the correct answer is **Therapsid**. Therapsids are the most current ancestors of modern mammals, as they are the lineage from which mammals evolved.

### Conclusion
The most current ancestor of modern mammals among the given options is **Therapsid**.

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