ORIGIN AND HISTORY OF LIFE ON EARTH

Cyanobacteria

played a crucial role in the Oxygen Revolution through photosynthesis, which led to the Great Oxygenation Event.

The Geologic Time Scale of Earth's History

the “calendar” for events in Earth’s history.

PRE-CAMBRIAN EONS

the longest eon and encompasses most of the Earth's history.

PHANEROZOIC

the most recent eon in Earth's history.

PALEOZOIC ERA

“ancient life”

It witnessed the emergence of fish, plants, insects, and the first terrestrial vertebrates. 

CAMBRIAN PERIOD

• known for the "Cambrian” Explosion.

• Trilobites

• Brachiopods

• Mollusks,

• Other complex organisms with hard shells.

ORDOVICIAN PERIOD

• evolution of diverse marine invertebrates.

• The first vertebrates, jawless fish appeared.

Ended with the Ordovician-Silurian Extinction

SILURIAN PERIOD

• colonization of land by early vascular plants

• First arachnids and centipedes appeared.

• Expansion and diversification of coral reefs.

DEVONIAN PERIOD

• Called the "Age of Fish" due to the diversification of jawed fish.

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• The first amphibians evolved.

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• The first trees emerged.

Ended with the Late Devonian Extinction

CARBONIFEROUS PERIOD

• Diversification of amphibians and the first appearance of reptiles.

• Insects became more abundant and diverse

PERMIAN PERIOD

• evolution of reptiles, including early synapsids.

• Diversification of seed plants (gymnosperms)

• ended with the Permian-Triassic extinction event

MESOZOIC ERA

often known as the era of middle life and is famous for the dominance of reptiles, including dinosaurs.

TRIASSIC PERIOD

• First mammals

• Archosaurs

• Ichthyosaurs

• Plesiosaurs

Ended with the Triassic-Jurassic Extinction

JURASSIC PERIOD

• Known for the dominance of dinosaurs. 

• The first birds evolved.

• Pangaea began to break apart, leading to the formation of separate landmasses.

CRETACEOUS PERIOD

• continued diversification of dinosaurs

• Flowering plants became widespread

• First true snakes appeared.

• ended with Cretaceous-Paleogene mass extinction event.

CENOZOIC ERA

the era of recent life and spans from the aftermath of the Cretaceous-Paleogene extinction event to the present day.

PALEOGENE PERIOD

• Adaptive radiation and diversification of Mammals

• Early primates appeared setting the stage for the evolution of monkeys and apes.

NEOGENE PERIOD

• Evolution of hominids (ancestors of humans).

• Evolution of grazing mammals like horses and elephants.

QUATERNARY PERIOD

• Homo sapiens, modern humans, evolved and became the dominant species on Earth.

• Continents continued to move and drift, affecting global climate and influencing the distribution of species

LUCA

• The most recent ancestral population from which all modern life descended

• It explains the unity of life by showing that all organisms share common molecular features, providing strong evidence for common descent and early evolution on Earth.

ABIOGENESIS

also known as "chemical evolution" proposes that life emerged from non-living matter through a series of chemical reactions.

RNA WORLD HYPOTHESIS

suggests that self-replicating RNA molecules played a crucial role in the early stages of life.

PANSPERMIA

proposes that life, or at least the building blocks of life, may have originated outside of Earth.