Timeline: History of the Earth

99,999 BCE

Earth is formed

The Earth is thought to have been formed 4.6 billion years ago by collisions of gas and dust.

99,998 BCE

Oxygen begins to form in the atmosphere

Cynobacteria. These microbes conduct photosynthesis: using sunshine, water and carbon dioxide to produce carbohydrates and oxygen. 2.7 billion years ago.

99,997 BCE

First forms of Life are on Earth

Earth's initial life forms were bacteria, which could survive in the highly toxic atmosphere that existed during this time. This occurred 2.5 billion years ago.

99,996 BCE

Pangea form

The giant ocean that surrounded the continent is known as Panthalassa. The movement of Earth's tectonic plates formed Pangaea and ultimately broke it apart. About 270 million years ago.

99,995 BCE

Pangea begins to break

At this time most of the dry land on Earth was joined into one huge landmass that covered nearly a third of the planet's surface. The giant ocean that surrounded the continent is known as Panthalassa. The movement of Earth's tectonic plates formed Pangaea and ultimately broke it apart. Broke apart about 200 million years ago.

99,994 BCE

1st multicellular organisms appear on earth

More complex forms of life took longer to evolve, with the first multicellular animals not appearing until about 600 million years ago.

99,993 BCE

1st eukaryotes appear

Eukaryotes are organisms with a nucleus. The oldest evidence of eukaryotes is from 2.7 billion years ago. Scientists believe that a nucleus and other organelles inside a eukaryotic cell formed when one prokaryotic organism engulfed another, which then lived inside and contributed to the functioning of its host.

99,992 BCE

Late Devonian extinction

416 million years ago

99,991 BCE

Permian–Triassic extinction event

The Permian–Triassic extinction event, colloquially known as the Great Dying, the End-Permian Extinction or the Great Permian Extinction, occurred about 252 Ma ago.

99,990 BCE

Triassic–Jurassic extinction event

The Triassic–Jurassic extinction event marks the boundary between the Triassic and Jurassic periods, 201.3 million years ago, and is one of the major extinction events of the Phanerozoic eon, profoundly affecting life on land and in the oceans