History of life on earth

Single-celled organisms with a nucleus and internal structure. They are the ancestors of all plants and animals.

A mutualistic partnership between plants and fungi. Plants provide food, fungi provide nutrients from organic matter.

The first animals to leave the water and live on land. Their fossils are found in rock layers dating back millions of years.

An early arthropod that was the first to successfully adapt to life on land.

The study of Earth's history by analyzing its rocks and the fossils they contain.

The earliest known life forms on Earth, appearing approximately 3.5 billion years ago.

The process by which bacteria produce energy using sunlight, releasing oxygen as a byproduct.

The process that describes how all life on Earth evolved from simple, single-celled organisms over millions of years.

Organisms made of multiple cells, including animals, plants, and fungi.

The sudden extinction of a large number of organisms, including the dinosaurs, during the Cretaceous period 65 million years ago.

The hypothesis that life on Earth originated on another planet and was brought to Earth through space.

The theory that life originated from non-living matter. It suggests that simple organic molecules in early Earth's environment combined and eventually formed the first living organisms.

The oldest fossils are bacteria, found in 3.6 billion-year-old rocks. This indicates that bacteria were among the first life forms on Earth.

A type of bacteria that is found in harsh environments, resembling the conditions of early Earth.

The most common type of bacteria, including those that cause disease and decomposition.

A specific type of bacteria capable of photosynthesis. They played a crucial role in adding oxygen to the early Earth's atmosphere.

The process by which cyanobacteria use sunlight to produce energy, releasing oxygen as a byproduct.

The key gas that allowed life to transition to land. Cyanobacteria's release of oxygen into the atmosphere led to the formation of the ozone layer, protecting life from harmful UV radiation.

A period of rapid diversification of life forms, including the evolution of animals, plants, and fungi.

The first animals to evolve, characterized by a simple body structure and no internal skeleton.

Organisms that have a backbone, including fish, amphibians, reptiles, birds, and mammals.

Jawless fishes were the only vertebrates for millions of years before the evolution of jawed fishes, which include sharks and bony fishes.

The evolution of more complex animals after the Cambrian Explosion, including scorpions and jawless fishes.

The first single-celled organisms with a nucleus, evolving from simpler prokaryotic cells.

The first organisms with a backbone, evolving from bony fishes.

Prehistoric reptiles that dominated the Earth for millions of years.

A period of rapid diversification of life forms, including animals, plants, and fungi.

These are single-celled organisms that are neither animals, plants, nor fungi. They are incredibly diverse.

The Geologic Time Scale is a hierarchical system of divisions used to organize Earth's history. It provides a framework for understanding the vast expanse of time and the events that shaped our planet.

An eon is the largest division of geologic time, encompassing hundreds to thousands of millions of years. It represents a major chapter in Earth's history.

An era is a subdivision of an eon, lasting hundreds of millions of years. It is characterized by distinct geological and biological events.

A period is a subdivision of an era, spanning tens of millions of years. It is defined by the types of life that existed during that time.

An epoch is the smallest division of the geologic time scale, lasting several million years. It is characterized by specific events within a period, such as extinction events or the appearance of a new species.

The division of geologic time is based on globally recognizable events, such as extinctions, magnetic pole reversals, or the appearance of new species. These events are recorded in rocks and fossils and are used to establish boundaries between different time intervals.

The International Commission on Stratigraphy sets the standards and guidelines for defining and dividing geologic time intervals. This commission ensures consistency and consensus among scientists worldwide.

The Geologic Time Scale provides us with a framework to understand Earth's history and the evolution of life over billions of years. Studying past events helps us understand the present and predict future changes.