Brenna Robinson's Geologic Timeline

Cambrian Period

541 BCE

The continent of Rodinia is broken apart, creating the ozone. The "snowball" earth has ended. Species begin getting more complex during this time (developing eyes, skeleton, teeth,etc.). There was more life on earth during this time than ever recorded.

Ordovician Period

485 BCE

Nearly all life was limited to diverse marine creatures. Most of the Earth's land was found on the southern supercontinent Gondwana.

Silurian Period

444 BCE

During this time, there wasn't much land and sea levels were rising. A class of jawless fish called Agnatha was the most common species found. The climate was warm and stable in this period.

Devonian Period

419 BCE

The Devonian Period is sometimes referred to as the "Age of the Fishes" due to the diverse, abundant marine life. In the end of the period, the first four legged amphibians appeared. The ocean, which covered 85% of the planet, experienced reduced dissolved oxygen levels which potentially caused the extinction of many species.

Carboniferous Period

359 BCE

Large plants occupy the surface for the first time. The period is characterized by it's tropical swamplands. It is called the carboniferous period due to the coal deposits originating from dead plants.

Permian Period

299 BCE

The Permian Period is the last period of the Paleozoic Era. The world consisted of two main continents called Pangaea and Siberia. The Permian ended with the largest mass extinction in the history of Earth: 95% of species died out due to mass volcanic eruptions.

Triassic Period

252 BCE

Earth had just experienced the mass extinctions in the Permian period, and didn't recover it's diversity until well into the Triassic Period. Dinosaurs first appeared during this period. Pangaea was the dominant continent and the climate was mostly hot and dry.

Jurassic Period

201 BCE

Dinosaurs were the dominant species during this time. The supercontinent Pangaea split apart and birds appeared for the first time. An upsurge in volcanic activity in this period caused the movement of plate tectonics, attributing to the development of many new mountains.

Cretaceous Period

145 BCE

Sections of Pangaea were still drifting apart and by the end of the period, they closely resembled the modern continents. Flowering plants developed for the first time and avian species become more diverse.

Tertiary Period

65 BCE

The planet was covered in thick vegetation. Dinosaurs and 70% of other species went extinct during this period due to volcanoes as well as a giant meteor, projected to be six miles in diameter.

Quaternary Period

2 BCE

The first ancestors of modern humans appeared. The Ice Age was triggered by a land bridge connecting North and South America, preventing the flow of warm water. Mammals like mammoths, rhinos, bison, and oxen all develop shaggy coats to combat the freezing temperatures.