Origin and Development of Life of Earth

Hadean Era (4.6-3.9 bya)

This era begins with the formation of the Earth.

• volcanic eruptions

• cosmic bombardments

• raging storms

• high temperatures

first organisms indicate life

Archean Era (3.9-2.5 bya)

first signs of life

• stromatolites: sedimentary formations that represent the early formation of life.

• there was mostly carbon dioxide in the atmosphere - cyanobacteria

Proterozoic Era (2.5 bya - 541 mya)

This represented an earlier life

• oxygen was released into the atmosphere

• photosynthetic bacteria

• multicellular life forms

New organisms, eukaryotes

Eukaryotic cells

contain a nucleus and organelles bound by plasma membranes

prokaryotic cells

do not have a membrane-bound nucleus or organelles

Phanerozoic Eon (541mya-present)

visible life forms

• life became obvious with trees, newts, dinosaurs, humans

• life as we know it

Paleozoic Era

diversification of visible life forms ( started with The Big Bang)

• complex animals mineralized remains

• land populated by plants and arthropods

The Great Dying

most severe extinction

• meteorite on coast of South America

• volcanic eruptions on Pangea

Mesozoic Era (age of reptiles)

dinosaurs and pterosaurs

mammals, frogs, bees, flowers

Cretaceous - Paleogene Extinction Event (66 mya)

• asteroid

• ash in the atmosphere

• sunlight blocked

• extreme cold

no sun meant plants and herbivores died leaving birds to survive.

Cenozoic Era (66 mya)

marks the rise of mammals

• temperature rose, forests spread, mammals recovered

• The climate warmed, mass extinction occurred, and humans began to thrive