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Evolution Of Life On Earth

Evolution is the process of how living beings evolve to form new species to expand their generation.

The Earth first formed about 4.5 billion years ago from a swirl of dust, cloud and debris from the Big Bang. Life evolved 500 million years after the Earth was formed. Fossils help us chart the story of life which evolved from a single-celled bacteria.

Earth’s geological time can be divided into blocks of eras. Earth is in the Quaternary period of the Cenozoic era.

4.6 BYA - 541 MYA

Precambrian:

This period was the first period of Earth where the first life evolved. This period represents 80 percent of the total geological time of Earth. Volcanic lava produced water where simple lifeforms evolved. Some of the lifeforms produced oxygen.

541 MYA - 252 MYA

Paleozoic era:

541 MYA - 485 MYA

Cambrian:

Many types of marine life evolved in this period. These marine life included mollusks, sponge and arthropods.

485 MYA - 443 MYA

Ordovician:

The first fish evolved in this period. Thai included the jawless Astraspis. Corals also evolved in this period. This period ended with a mass extinction.

443 MYA - 419 MYA

Silurian:

Plants, such as Cooksonia evolved on land. There were more fish in the water and echinoderms too.

419 MYA - 358 MYA

Devonian:

New types of fish and sharks evolved such as the lobe-finned Tiktalik and the Stenacanthus shark which had an antenna.

358 MYA - 298 MYA

Carboniferous:

Swamps grew on land and life flourished. Reptiles such as Spinoaequalis and synapsids, the ancestor of mammals, such as Ophiacodon evolved.

298 MYA - 252 MYA

Permian:

Hot and dry weather in this period caused cold-blooded animals like Eothyris to evolve. A huge catastrophic mass extinction wiped out 90 percent of all living organisms on Earth at the end of this period.

252 MYA - 66 MYA

Mesozoic era:

252 MYA - 201 MYA:

Triassic:

The creatures which survived the permian extinction evolved into different types of animals such as the first mammals like Morgacunodon and first dinosaurs such as Plateosaurus. This period ended just like it had begun.

201 MYA - 145 MYA

Jurassic:

Reptiles began to flourish in this period. Some ruled the land and sea while others took to the skies. Long-necked plant eaters appeared in this period.

145 MYA - 66 MYA

Cretaceous:

This period was the last and the longest period of the Mesozoic era. There were astonishing species of new dinosaurs and monsters of the oceans. This period ended with a mass extinction that wiped out 75 percent of the world’s animals.

66 MYA - Present day

Cenozoic era

66 MYA - 23 MYA

Paleogene:

The surviving mammals filled the Earth and the age of mammals began. The ancestors of humans, the Australopithecus evolved in this era.

23 MYA - 2.58 MYA

Neogene Period:

This period was a time of immense geological and biological transition. Continents shifted to their modern place and the Himalayas and Alps rose and the cooling climate caused dense forests to grow.

2.58 MYA - Present

Quaternary period:

This is the current and the most recent time period in history. It is defined by repeated cycles of global glaciations, the evolution and spreading of human beings and the extinction of the megafauna.