During cretaceous-palaeocene mass extinction the organisms that became extinct were

Options

A. Mammoths
B. Dinosaurs
C. Trilobites
D. Marine amphibians.

Answer

### Step-by-Step Solution:

1. **Understanding the Cretaceous-Paleocene Mass Extinction**:
- This mass extinction event occurred approximately 66 million years ago and is one of the five major extinction events in Earth's history.

2. **Identifying the Affected Organisms**:
- During this event, it is estimated that about one-third of all species on Earth became extinct, including many plants and animals.

3. **Dominant Species Extinct**:
- The most notable group that went extinct during this period was the dinosaurs. They were the dominant terrestrial vertebrates of that time.

4. **Other Extinct Groups**:
- In addition to dinosaurs, other groups that became extinct included:
- **Mammoths**: Large mammals that roamed the Earth.
- **Trilobites**: Marine arthropods that had existed for hundreds of millions of years.
- **Marine Amphibians**: Such as ichthyosaurs and mosasaurs, which were significant marine predators.

5. **Conclusion**:
- The primary group of organisms that became extinct during the Cretaceous-Paleocene mass extinction was the dinosaurs.

### Final Answer:
The organisms that became extinct during the Cretaceous-Paleocene mass extinction were primarily dinosaurs.

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