History of the Earth

Let's look at time...

Scientists like to use abbreviations or shortcuts

Instead of writing out

4,600,000,000 years

to explain the history of the earth

they write

4.6 billion years

Let's look at time...

Or they can write it as4.6 Ga

(because even billion was too much to write)

If scientists want to write million years ago

they would write

540 million years or

540 Ma

Which is older?

something that is 600 Ma or something that is 3.2 Ga

Looking at the Paleozoic

Cambrian Period● Our fossil records show the first

marine invertebrates

Looking at the Paleozoic

Silurian

Period

First land plants show up in the fossil

record

Looking at the Paleozoic

Silurian PeriodFirst Insects appear in the fossil

record

Looking at the Paleozoic

Fish are the dominant species in the fossil record

Devonian Period

Looking at the Paleozoic

Amphibians appear in the fossil record

Devonian Period

Looking at the Paleozoic

Permian Period

Fossils indicate a type of early

reptile

Looking at the Mesozoic

Triassic Period

Fossils indicate the first mammals appear during this period

Looking at the Mesozoic

Jurassic Period

Dinosuars dominated during this period

Looking at the Mesozoic

Cretaceous Period – Tertiary Period (Paleocene epoch)

Dinosuars became extinct in what is called the K-T extinction. About 65 million years ago

Looking at the Cenozoic

Oligocene Epoch

First primitive apes appeared

Looking at the Cenozoic

Pleistocene Epoch

First species to resemble modern humans appear in our fossil record