Land reptiles that went back into water evolve into fish-like reptiles probably 200 mya. Example of such reptile is:
(a) Tyrannosaurus rex
(b) Ichthyosaurs
(c) Archaeopteryx
(d) Stegosaurus

Options

A. Tyrannosaurus rex
B. Ichthyosaurs
C. Archaeopteyx
D. Stegosaurus

Answer

To solve the question, we need to identify which of the given options represents a land reptile that evolved back into the water and became fish-like around 200 million years ago. Let's analyze each option step by step:

1. **Understanding the Question**:
- The question asks for an example of a land reptile that evolved into a fish-like reptile around 200 million years ago.

2. **Analyzing the Options**:
- **(a) Tyrannosaurus rex**:
- Tyrannosaurus rex, commonly known as T-Rex, is a large theropod dinosaur that lived on land. It is not an aquatic organism, so it cannot be the correct answer.

- **(b) Ichthyosaurs**:
- The term "Ichthyosaurus" comes from "ichthyo," meaning fish-like. Ichthyosaurs are indeed fish-like reptiles that evolved from land reptiles and adapted to life in the water around 200 million years ago. This makes it a strong candidate for the correct answer.

- **(c) Archaeopteryx**:
- Archaeopteryx is considered a transitional fossil between reptiles and birds. While it is an important evolutionary link, it does not represent a return to an aquatic lifestyle from land, so it is not the correct answer.

- **(d) Stegosaurus**:
- Stegosaurus is a genus of herbivorous dinosaurs that lived on land. Like T-Rex, it is not associated with an aquatic lifestyle, making it an incorrect option.

3. **Conclusion**:
- Based on the analysis, the only option that fits the description of a land reptile that evolved into a fish-like reptile is **(b) Ichthyosaurs**.

Final Answer: **(b) Ichthyosaurs**