Reptiles of different shapes and sizes dominated Earth. Which reptile went back into water to evolve into fish like reptiles 200 mya ?

Options

A. Ichthyosaurs
B. Tyrannosaurus
C. Hemidactylus
D. Pelycosaurs

Answer

To solve the question of which reptile went back into the water to evolve into fish-like reptiles around 200 million years ago, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Context**: The question mentions reptiles that dominated the Earth and specifically asks about a reptile that evolved into fish-like reptiles. This indicates a transition from land to aquatic life.

**Hint**: Think about the evolutionary history of reptiles and their adaptations to different environments.

2. **Identifying Key Terms**: The term "Ichthyosaur" is crucial here. The prefix "Ichthy-" refers to fish, while "-saur" refers to lizards or reptiles. This suggests that Ichthyosaurs are reptiles that adapted to an aquatic lifestyle.

**Hint**: Look for the meanings of prefixes and suffixes in scientific names to understand their characteristics.

3. **Reviewing Geological History**: Ichthyosaurs existed during the Mesozoic era, particularly in the Triassic and Jurassic periods. They were among the first reptiles to return to the sea, adapting to an aquatic environment.

**Hint**: Consider the timeline of reptile evolution and the major periods in which different reptiles thrived.

4. **Eliminating Incorrect Options**:
- **Tyrannosaurus**: A well-known dinosaur, not aquatic.
- **Hemidactylus**: A common wall lizard, not related to aquatic evolution.
- **Pelicosaur**: An early reptile, but not specifically related to fish-like adaptations.

**Hint**: Cross-reference the characteristics of each option with the requirements of the question.

5. **Concluding the Answer**: Based on the information gathered, the correct answer is **Ichthyosaur**, as it is the reptile that evolved back into the water and became fish-like.

**Hint**: Summarize the key points that led to the conclusion to reinforce understanding.

### Final Answer:
**Ichthyosaur** is the reptile that went back into water to evolve into fish-like reptiles around 200 million years ago.