Thecodont teeth are present in
a. Sphenodon
b. Crocodiles
c. Mammals
d. Scoliodon

Options

A. c only
B. b & c only
C. a, b & c only
D. a, b, c & d

Answer

To determine which organisms possess thecodont teeth, we need to analyze the options given:

1. **Understanding Thecodont Teeth**: Thecodont teeth are characterized by being embedded in sockets within the jawbone. This type of dentition provides a firm attachment and is a distinguishing feature in certain groups of animals.

2. **Analyzing the Options**:
- **a. Sphenodon**: This is a reptile known as the tuatara. It does not possess thecodont teeth; instead, it has acrodont teeth, which are not set in sockets.
- **b. Crocodiles**: Crocodiles are indeed known to have thecodont teeth. They have a strong jaw structure with teeth that are firmly embedded in sockets.
- **c. Mammals**: Mammals also possess thecodont teeth. Their teeth are similarly embedded in sockets, which is a common feature among them.
- **d. Scoliodon**: This is a type of shark. Scoliodon has a different type of dentition and does not have thecodont teeth.

3. **Conclusion**: Based on the analysis, the organisms that possess thecodont teeth are crocodiles and mammals. Therefore, the correct answer is **b. Crocodiles** and **c. Mammals**.

### Final Answer:
Thecodont teeth are present in:
- b. Crocodiles
- c. Mammals