The recent ancestors of modern man were

Options

A. Therapsida
B. Ornithischia
C. Silusoidea
D. Chelonia.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question is asking about the recent ancestors of modern humans. To answer this, we need to identify the correct group of ancestors from the given options.

2. **Identifying the Correct Group**: The correct answer is **Therapsida**. This group is known to be the ancestors of mammals, including modern humans.

3. **Explaining Why Therapsida is Correct**:
- Therapsida is a group of synapsid reptiles that are considered to be the ancestors of mammals.
- They exhibit several characteristics that are similar to modern mammals, such as:
- Vertical limbs, which are more efficient for locomotion.
- Large jaws and heterodont teeth, which allow for a varied diet.
- Presence of hair or fur, which is a characteristic feature of mammals.
- Ability to regulate body temperature, indicating a more advanced metabolic system.

4. **Evaluating Other Options**:
- **Ornithischia**: This group is incorrect as it refers to a clade of dinosaurs, specifically the ancestors of birds.
- **Psilosoidea**: This option is incorrect because it does not represent a recognized group of ancestors.
- **Chilonia**: This group is also incorrect as it pertains to turtles, which are not related to the ancestry of modern humans.

5. **Conclusion**: Based on the analysis, the correct answer to the question is **Therapsida**.