ACROSS
1. It refers to the system of chronological dating that relates geological strata to
time.
2. It refers to the time of hidden life.
3. It is also known as the age of mammals.
4. This is the time where first amphibians made their appearance.
5. The evolution of first reptiles took place.
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6. It refers to a unit of geological time equal to billion years.
7. It is the time where first terrestrial life and vascular plants appeared.
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8. It is an era that began about 544 million years ago and lasted about 300 million
years.
9. It is a period of time in history that is a subdivision of an eon.
10. It refers to the subdivision of an era.