biology

What era marked the first appearance of humans

last several millions of years and are the smallest units of time

last tens of millions of years; two or more epochs

hundreds of millions of years; two or more periods

longest unit of geological time; can include billions of years

What is the importance of uranium

90% of Earths history was spent during which era

What period is marked by the first flowering plants

The movement of several large plates that make up the surface of the Earth, also played a role in the Mass Extinction of dinosaurs

How old are the oldest fossils on Earth