Timeline of evolution

Timeline of Evolution

	Email		Print
	Bookmark		Link

Timeline of evolution

This timeline of the evolution of life outlines the major events in the development of life

Life

Life is a characteristic of organisms that exhibit certain biological processes such as chemical reactions or other events that results in a transformation....
on the planet Earth

Earth

Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
(See Organism

Organism

In biology, an organism is any life thing . In at least some form, all organisms are capable of response to stimulus , reproduction, growth and developmental biology, and maintenance of homeostasis as a stable whole....
). For a thorough explanatory context, see the history of Earth

History of Earth

The history of the Earth covers approximately Age of the Earth , from Earth?s formation out of the solar nebula to the present. This article presents a broad overview, summarizing the leading, most current scientific theories....
, and geologic time scale

Geologic time scale

File:Geologic clock.jpgThe geologic time scale is a chronology schema relating stratigraphy to time that is used by geologys and other earth sciences scientists to describe the timing and relationships between events that have occurred during the history of the Earth....
. The dates given in this article are estimates based on scientific evidence.

In biology

Biology

Biology is a branch of the natural sciences concerned with the study of living organisms and their interaction with each other and their environment ....
, evolution

Evolution

In biology, evolution is change in the heritability trait of a population of organisms from one generation to the next. These changes are caused by a combination of three main processes: variation, reproduction, and selection....
is the process by which populations of organisms acquire and pass on novel traits from generation to generation. Its occurrence over large stretches of time explains the origin of new species

Speciation

Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages....
and ultimately the vast diversity of the biological world.

Discussion

Ask a question about 'Timeline of evolution'

Start a new discussion about 'Timeline of evolution'

Answer questions from other users

Full Discussion Forum

Encyclopedia

This timeline of the evolution of life outlines the major events in the development of life

Life

Life is a characteristic of organisms that exhibit certain biological processes such as chemical reactions or other events that results in a transformation....
on the planet Earth

Earth

Organism

History of Earth

Geologic time scale

Biology

Biology is a branch of the natural sciences concerned with the study of living organisms and their interaction with each other and their environment ....
, evolution

Evolution

Speciation

Common descent

A group of organisms is said to have common descent if they have a common ancestor. In modern biology, it is generally accepted that all living organisms on Earth are descended from a common ancestor or ancestral gene pool....
, products of evolution and speciation

Speciation

Basic timeline

The basic timeline is a 4.6 billion year old Earth

Age of the Earth

Modern Geology and geophysicists consider the age of the Earth to be around 1 E17 s This age has been determined by Radiometric dating of meteorite material and is consistent with the ages of the oldest-known terrestrial and Earth's moon Moon rock....
, with (very approximate) dates:

3.8 billion years of simple cells
Prokaryote

The prokaryotes are a group of organisms that lack a cell nucleus , or any other cell membrane-bound organelles. They differ from the eukaryotes, which have a cell nucleus....
(prokaryotes),
3 billion years of photosynthesis
Photosynthesis

File:Seawifs global biosphere.jpgPhotosynthesis is a metabolic pathway that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight....
,
2 billion years of complex cells
Eukaryote

Animals, plants, fungus, and protists are eukaryotes , organisms whose Cell are organized into complex structures enclosed within Cell membrane....
(eukaryotes),
1 billion years of multicellular life
Evolution of multicellularity

The first organisms that existed are believed to have been unicellular. How organisms then became multicellular is a huge evolutionary step and is consequently under great debate....
,
600 million years of simple animal
Animal

Animals are a major group of multicellular, eukaryotic organisms of the Kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life....
s,
570 million years of arthropods (ancestors of insects, arachnids and crustaceans)
550 million years of complex animals
500 million years of fish
Fish

A fish is any marine biology vertebrate animal that is typically ectothermic , covered with scale , and equipped with two sets of paired fins and several unpaired fins....
and proto-amphibians,
475 million years of land plants,
400 million years of insect
Insect

Insects are the biggest class of arthropods and the only ones with wings. They are the most diverse group of animals on the planet. They are most diverse at the equator and their diversity declines toward the poles....
s and seed
Seed

A seed is a small Plant embryogenesis plant enclosed in a covering called the seed coat, usually with some Food storage. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant....
s,
360 million years of amphibian
Amphibian

Amphibians , such as frogs, toads, salamanders, newts and caecilians, are cold-blooded animals that metamorphose from a juvenile, water-breathing form to an adult, air-breathing form....
s,

300 million years of reptile
Reptile

Reptiles, or members of the class Reptilia, are air-breathing, cold-blooded vertebrates that have skin covered in scale as opposed to hair or feathers....
s
200 million years of mammal
Mammal

Mammals are a class of vertebrate animals whose name is derived from their distinctive feature, mammary glands, with which they feed their young....
s,
150 million years of bird
Bird

Birds are wing, Bipedalismal, endothermic , vertebrate animals that lay egg . There are around 10,000 living species, making them the most numerous tetrapod vertebrates....
s,
130 million years of flower
Flower

A flower, sometimes known as a bloom or blossom, is the reproduction structure found in flowering plants . The biological function of a flower is to mediate the union of male sperm with female ovum in order to produce seeds....
s,
65 million years since the non-avian dinosaur
Dinosaur

Dinosaurs were the dominant vertebrate animals of Landform ecosystems for over 160 million years, from the late Triassic Period until the end of the Cretaceous Period , when most of them became extinct in the Cretaceous?Tertiary extinction event....
s died out,
2.5 million years since the appearance of the genus Homo
Homo (genus)

Homo is the genus that includes anatomically modern humanss and their close relatives. The genus is estimated to be about 2.5 million years old, evolving from Australopithecine ancestors with the appearance of Homo habilis....
,
200,000 years since humans
Homo (genus)

Homo is the genus that includes anatomically modern humanss and their close relatives. The genus is estimated to be about 2.5 million years old, evolving from Australopithecine ancestors with the appearance of Homo habilis....
started looking like they do today,
25,000 years since Neanderthal
Neanderthal

The Neanderthal , or Neandertal, is an extinct member of the Homo genus that is known from Pleistocene specimens found in Europe and parts of western and central Asia....
s died out.

Detailed timeline

Note that Mya means "million years ago".

Hadean
Hadean

The Hadean is the Eon before the Archean. It started at Earth formation about 4.6 billion years ago , and ended roughly 3.8 billion years ago, though the latter date varies according to different sources....
eon

3800 Mya and earlier.

Date	Event
4567.17 Mya	The planet Earth Earth Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather... forms from the accretion disc Accretion disc An accretion disc is a structure formed by diffuse material in orbital motion around a central body. The central body is typically a young star, a protostar, a white dwarf, a neutron star, or a black hole.... revolving around the young Sun Sun The Sun , a G V star, is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 98.6% of the Solar System's mass.... .
4533 Mya	According to one plausible theory, the planet Earth and the planet Theia Theia (planet) Theia is a hypothetical planet that, according to the giant impact hypothesis gave rise to the Moon. Theia is believed to have collided with Earth over 4.5 billion years ago.... collide, sending countless moonlets into orbit around the young Earth. These moonlets eventually coalesce to form the Moon Moon The Moon is Earth's only natural satellite and the List of natural satellites by diameter satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is km, about thirty times the diameter of the Earth.... . The gravitational pull of the new Moon stabilises the Earth's fluctuating axis of rotation and sets up the conditions for the formation of life.
4100 Mya	The surface of the Earth cools enough for the crust Crust (geology) In geology, a crust is the outermost solid shell of a planet or moon, which is chemically distinct from the underlying mantle . Crusts of Earth , our Moon, Mercury , Venus, and Mars have been generated largely by igneous processes, and these crusts are richer in incompatible elements than their respective mantle s.... to solidify. The atmosphere Earth's atmosphere The Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by the Earth's gravity. Dry air contains roughly 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% Carbon dioxide in the Earth's atmosphere, and trace amounts of other gases.... and the ocean Ocean An ocean is a major body of Seawater, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a World Ocean that is customarily divided into several principal oceans and smaller seas.... s form.PAH PAH world hypothesis The PAH world hypothesis is a Origin of life hypothesis that proposes that the use of polycyclic aromatic hydrocarbons was a means for a pre-RNA World basis for the origin of life.... infall, and Iron-Sulfide synthesis along deep ocean platelet boundaries, may have led to the RNA world of competing metabolising organic compounds.
Between 4500 and 2500 Mya	The earliest life appears, possibly derived from self-reproducing RNA world hypothesis The RNA world hypothesis proposes that a world filled with life based on ribonucleic acid predated current life based on deoxyribonucleic acid .... RNA RNA Ribonucleic acid is a type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nucleobase, a ribose sugar, and a phosphate.... molecules. The replication of these organisms requires resources like energy, space, and smaller building blocks, which soon become limited, resulting in competition. Natural selection Natural selection Natural selection is the process by which favorable heritable trait become more common in successive generations of a population of Reproduction organisms, and unfavorable heritable traits become less common, due to differential reproduction of genotypes.... favours those molecules which are more efficient at replication. DNA DNA Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses.... molecules then take over as the main replicators. They soon develop inside enclosing membranes which provide a stable physical and chemical environment conducive to their replication: proto-cells Cell (biology) The cell is the structural and functional unit of all known Life organisms. It is the smallest unit of an organism that is classified as living, and is often called the building bricks of life.... .
3900 Mya	Late Heavy Bombardment Late Heavy Bombardment The Late Heavy Bombardment is a period of time approximately 3,800 to 4,100 million years ago during which a large number of impact craters are believed to have formed on the Moon, and by inference on Earth, Mercury , Venus, and Mars as well.... : peak rate of impact event Impact event An impact event is the collision of a large meteoroid, asteroid or comet with the Earth. Impact events have been a plot and background element in science fiction since knowledge of real impacts became established in the scientific mainstream.... s upon the inner planets by meteors. This constant disturbance Disturbance In ecology, a disturbance is a temporary change in average environmental conditions that causes a pronounced change in an ecosystem. Outside disturbance forces often act quickly and with great effect, sometimes resulting in the removal of large amounts of biomass.... probably obliterated any life that had already evolved, as the oceans boiled away completely; conversely, life may have been transported to Earth Panspermia Panspermia is the hypothesis that "seeds" of life exist already all over the Universe, that life on Earth may have originated through these "seeds", and that they may deliver or have delivered life to other habitable bodies.... by a meteor.
Somewhere between 3900 - 2500 Mya	Cells Cell (biology) The cell is the structural and functional unit of all known Life organisms. It is the smallest unit of an organism that is classified as living, and is often called the building bricks of life.... resembling prokaryote Prokaryote The prokaryotes are a group of organisms that lack a cell nucleus , or any other cell membrane-bound organelles. They differ from the eukaryotes, which have a cell nucleus.... s appear. These first organisms are chemoautotrophs Chemotroph Chemotrophs are organisms that obtain energy by the oxidation of electron donating molecules in their environments. These molecules can be organic molecule or inorganic .... : they use carbon dioxide Carbon dioxide Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state.... as a carbon Carbon Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds.... source and oxidize Redox Redox describes all chemical reactions in which atoms have their oxidation number changed.This can be either a simple redox process such as the oxidation of carbon to yield carbon dioxide or the reduction of carbon by hydrogen to yield methane , or it can be a complex process such as the oxidation of sugar in the human body through a ser... inorganic materials to extract energy. Later, prokaryotes evolve glycolysis Glycolysis Glycolysis is the metabolic pathway that converts glucose, C6H12O6, into pyruvate, C3H5O3-.... , a set of chemical reactions that free the energy of organic molecules such as glucose Glucose Glucose , a monosaccharide also known as grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology.... . Glycolysis generates ATP Adenosine triphosphate This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer.... molecules as short-term energy currency, and ATP continue to be used in almost all organisms, unchanged, to this day.

Archean
Archean

The Archean is a geology eon before the Proterozoic and Paleoproterozoic, before 2.5 Ga . Instead of being based on stratigraphy, this date is defined chronometrically....
eon

3800 Mya - 2500 Mya

Date	Event
3500 Mya	Lifetime of the last universal ancestor Last universal ancestor The last universal ancestor is the most recent organism from which all organisms now living on Earth Common descent. Thus it is the most recent common ancestor of all current life on Earth.... ; the split between the bacteria Bacteria The Bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals.... and the neomura Neomura Neomura is a speculative clade composed of the two Domain of Archaea and Eukaryote. The group was first proposed by Thomas Cavalier-Smith and its name means "new walls"; so called because it is thought to have evolution from Bacteria, and one of the major changes was the replacement of peptidoglycan cell walls with other glycoproteins.... occurs. Bacteria develop primitive forms of photosynthesis Photosynthesis File:Seawifs global biosphere.jpgPhotosynthesis is a metabolic pathway that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight.... which at first do not produce oxygen Oxygen Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]... . These organisms generate ATP Adenosine triphosphate This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer.... by exploiting a proton gradient Electrochemical gradient An electrochemical gradient is a spatial variation of both electrical potential and chemical concentration across a membrane. Both components are often due to ion gradients, particularly proton gradients, and the result can be a type of potential energy available for work in a cell.... , a mechanism still used in virtually all organisms.
3000 Mya	Photosynthesizing cyanobacteria Cyanobacteria Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of bacteria that obtain their energy through photosynthesis.... evolve; they use water as a reducing agent Reducing agent A reducing agent is the element or compound in a redox reaction that reduces another Chemical species. In doing so, it becomes oxidized, and is therefore the electron donor in the redox.... , thereby producing oxygen Oxygen Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]... as waste product. The oxygen initially oxidizes dissolved iron in the oceans, creating iron ore Iron ore Iron ores are Rock and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in colour from dark grey, bright yellow, deep purple, to rusty red.... . The oxygen concentration in the atmosphere Atmosphere An atmosphere is a layer of gases that may surround a material body of sufficient mass, by the gravity of the body, and are retained for a longer duration if gravity is high and the atmosphere's temperature is low.... subsequently rises, acting as a poison for many bacteria. The moon Moon The Moon is Earth's only natural satellite and the List of natural satellites by diameter satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is km, about thirty times the diameter of the Earth.... is still very close to the earth and causes tide Tide Tides are the rising of Earth's ocean surface caused by the tidal forces of the Moon and the Sun acting on the oceans. Tides cause changes in the depth of the marine and estuary water bodies and produce oscillating currents known as tidal streams, making prediction of tides important for coastal navigation .... s 1000 feet high. The earth is continually wracked by hurricane force winds. These extreme mixing influences are thought to stimulate evolutionary processes. (See Oxygen Catastrophe Oxygen Catastrophe The Oxygen Catastrophe was a massive environmental change believed to have happened during the Siderian geologic period at the beginning of the Paleoproterozoic era of the Precambrian, about 2.4 billion years ago.... )

Proterozoic
Proterozoic

The Proterozoic is a eon representing a period before the first abundant complex life on Earth. The Proterozoic Eon extended from 2500 annum to 542.0 ? 1.0 Ma , and is the most recent part of the old, informally named ?Precambrian? time....
eon

2500 Mya - 542 Mya

Date	Event
By 2100 Mya	Eukaryotic Eukaryote Animals, plants, fungus, and protists are eukaryotes , organisms whose Cell are organized into complex structures enclosed within Cell membrane.... cells appear. Eukaryotes contain membrane-bound organelle Organelle In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid membrane.... s with diverse functions, probably derived from prokaryote Prokaryote The prokaryotes are a group of organisms that lack a cell nucleus , or any other cell membrane-bound organelles. They differ from the eukaryotes, which have a cell nucleus.... s engulfing each other via phagocytosis Phagocytosis File:Phagocytosis in three steps.pngPhagocytosis is the cell process of Phagocytes and Protists of engulfing solid particles by the cell membrane to form an internal phagosome, which is a food vacuole, or pteroid.... .
By 1200 Mya	Sexual reproduction Sexual reproduction Sexual reproduction is characterized by processes that pass a Genetic recombination of Genetics material to offspring, resulting in Genetic diversity.... evolves, increasing the rate of evolution. Goddard and colleagues instead turned to a single-celled organism, yeast, to test the idea that sex allows populations to adapt to new conditions more rapidly than asexual populations." (URL accessed on January 9, 2005)
1200 Mya	Simple multicellular organism Multicellular organism Multicellular organisms are organisms consisting of more than one cell , and having differentiated cells that perform specialized functions in the cell.... s evolve Evolution of multicellularity The first organisms that existed are believed to have been unicellular. How organisms then became multicellular is a huge evolutionary step and is consequently under great debate.... , mostly consisting of cell colonies of limited complexity.
850–630 Mya	A global glaciation Snowball Earth Snowball Earth refers to hypotheses regarding paleoclimate global-scale glaciation, claiming that the Earth's surface was nearly or entirely frozen at some points in its past.... may have reduced the diversity of life. Opinion is divided on whether it increased or decreased the rate of evolution.
580-542 Mya	The Ediacaran biota represent the first large, complex multicellular organisms - although their affinities remain a subject of debate.
580–500 Mya	Most modern phyla Phylum A phylum "Phylum" is adopted from the Greek phylai, the clan-based voting groups in Greek city-states. is a taxonomic rank below Kingdom and above Class .... of animals begin to appear in the fossil record during the Cambrian explosion Cambrian explosion The Cambrian explosion or Cambrian radiation was the seemingly rapid appearance of most major groups of complex animals around , as evidenced by the fossil record.... .
Around 540 Mya	The accumulation of atmospheric oxygen allows the formation of an ozone layer Ozone layer The ozone layer is a layer in Earth's atmosphere which contains relatively high concentrations of ozone . This layer absorbs 93-99% of the sun's high frequency ultraviolet light, which is potentially damaging to life on earth.... . This blocks ultraviolet Ultraviolet Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than x-rays, in the range 400 nanometer to 10 nm, and energies from 3 Electron volt to 124 eV.... radiation, permitting the colonisation of the land.

Phanerozoic eon

542 Mya - present

The Phanerozoic

Phanerozoic

The Phanerozoic Eon is the current eon in the geologic timescale, and the one during which abundant animal life has existed. It covers roughly 545 million years and goes back to the time when diverse hard-shelled animals first appeared....
eon, literally the "period of well-displayed life", marks the appearance in the fossil record of abundant, shell-forming and/or trace-making organisms. It is subdivided into three eras, the Paleozoic, Mesozoic and Cenozoic, which are divided by major mass extinctions.

Paleozoic
Paleozoic

The Paleozoic or Palaeozoic Era is the earliest of three geology Era of the Phanerozoic Eon . The Paleozoic spanned from roughly , and is subdivided into six period ; from oldest to youngest they are: the Cambrian, Ordovician, Silurian, Devonian period, Carboniferous, and Permian...
era

542 Mya - 251.0 Mya

Date	Event
530 Mya	The first known footprints on land date to 530 Mya, indicating that early animal explorations may have predated the development of terrestrial plants.
475 Mya	The first primitive plant Plant Plants are Life organisms belonging to the Kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae.... s move onto land, having evolved from green algae living along the edges of lakes. They are accompanied by fungi Fungus A fungus is a Eukaryote organism that is a member of the Kingdom Fungi . The fungi are a monophyletic group, also called the Eumycota , that is phylogeny distinct from the morphologically similar slime molds and water molds .... , which may have aided the colonisation of land through symbiosis Symbiosis The term symbiosis commonly describes close and often long-term interactions between different biological species. The term was first used in 1879 by the Germany mycology Heinrich Anton de Bary, who defined it as "the living together of unlike organisms".... .
363 Mya	By the start of the Carboniferous Carboniferous The Carboniferous is a geologic period that extends from the end of the Devonian period, about 359.2 ? 2.5 annum , to the beginning of the Permian period, about 299.0 ? 0.8 Ma ... period, the Earth begins to be recognisable. Insect Insect Insects are the biggest class of arthropods and the only ones with wings. They are the most diverse group of animals on the planet. They are most diverse at the equator and their diversity declines toward the poles.... s roamed the land and would soon take to the skies; shark Shark Sharks are a type of fish with a full Cartilage skeleton and a highly Streamlines, streaklines and pathlinesd body. They respire with the use of five to seven gill slits.... s swam the oceans as top predators, and vegetation covered the land, with seed-bearing plants and forests soon to flourish. Four-limbed tetrapod Tetrapod Tetrapods are vertebrate animals having four feet, legs or leglike appendages. Amphibians, reptiles, dinosaurs/birds, and mammals are all tetrapods, and even the limbless snakes are tetrapods by descent.... s gradually gain adaptations which will help them occupy a terrestrial life-habit.
251.4 Mya	The Permian-Triassic extinction event Permian-Triassic extinction event The Permian?Triassic extinction event, informally known as the Great Dying, was an extinction event that occurred , forming the boundary between the Permian and Triassic geologic periods.... eliminates over 95% of species. This "clearing of the slate" may have led to an ensuing diversification.

Mesozoic
Mesozoic

The Mesozoic Era is one of three Geologic time scale of the Phanerozoic eon . The division of time into eras dates back to Giovanni Arduino, in the 18th century, although his original name for the era now called the 'Mesozoic' was 'Secondary' ....
era

Date	Event
From 251.4 Mya	The Mesozoic Marine Revolution Mesozoic Marine Revolution The Mesozoic marine revolution was a fundamental restructuring of marine ecosystems during the Mesozoic period caused by increased predation pressure.... begins: increasingly well-adapted and diverse predators pressurise sessile marine groups; the "balance of power" in the oceans shifts dramatically as some groups of prey adapt more rapidly and effectively than others.
220 Mya	Gymnosperm Gymnosperm Gymnosperm is a group of spermatophyte seed-bearing plants with ovules on scales, which are usually arranged in cone-like structures. The other major group of seed-bearing plants, the angiosperms, [from the Greek, 'angion' - container] have ovules enclosed in a carpel, a sporophyll with fused margins.... forests dominate the land; herbivores grow to huge sizes in order to accommodate the large guts necessary to digest the nutrient-poor plants.
200 Mya	The first accepted evidence for virus Virus A virus is a Optical microscope#Limitations of light microscopes infectious agent that is unable to grow or reproduce outside a host cell . Viruses infect all cellular life.... es (at least, the group Geminiviridae Geminiviridae Geminiviruses are plant viruses which have ambisense single-stranded circular DNA genomes and are members of class II of the Baltimore classification of viruses.... ) exists. Viruses are still poorly understood and may have arisen before "life" itself, or may be a more recent phenomenon.
130 Mya	The rise of the Angiosperms: These flower Flower A flower, sometimes known as a bloom or blossom, is the reproduction structure found in flowering plants . The biological function of a flower is to mediate the union of male sperm with female ovum in order to produce seeds.... ing plants boast structures that attract insects and other animals to spread pollen Pollen Pollen is a fine to coarse powder consisting of *Gametophyte* , which produce the male gametes of spermatophyta. A hard coat covering the pollen grain protects the sperm cells during the process of their movement between the stamens of the flower to the pistil of the next flower.... . This innovation causes a major burst of animal evolution through co-evolution Co-evolution In a broad sense, biological coevolution is "the change of a biological object triggered by the change of a related object". Coevolution can occur at multiple levels of biology: it can be as microscopic as correlated mutations between amino acids in a protein, or as macroscopic as covarying traits between different species in an environment... .

Cenozoic
Cenozoic

The Cenozoic Era...
era

65.5 Mya - present

Date	Event
65.5 Mya	The Cretaceous–Tertiary extinction event eradicates about half of all animal species, including all dinosaurs except the ancestors of modern birds Modern birds Modern birds are the most recent common ancestor of all living birds and all its descendants.Modern birds are body plan by feathers, a beak with no tooth , the laying of hard-shelled eggs, a high metabolism rate, a four-chambered heart, and a lightweight but strong Bird skeleton....
35 Mya	Grasses Poaceae Poaceae or Gramineae is a family in the Class Liliopsida of the Magnoliophyta. Plants of this family are usually called grasses; the shrub- or tree-like plants in this family are called bamboo .... evolve from among the angiosperms; grassland dominates many terrestrial ecosystems.
200 kya (200,000 years ago)	Anatomically modern humans appear in Africa. Around 50,000 years before present they start colonising the other continents, replacing the Neanderthal Neanderthal The Neanderthal , or Neandertal, is an extinct member of the Homo genus that is known from Pleistocene specimens found in Europe and parts of western and central Asia.... s in Europe and other hominins in Asia. The Holocene Holocene The Holocene is a geological Epoch which began approximately 11,700 years ago . According to traditional geological thinking, the Holocene continues to the present.... epoch starts 10,000 years ago after the Last Glacial Maximum Last Glacial Maximum The Last Glacial Maximum refers to the time of maximum extent of the ice sheets during the last glaciation , approximately 20,000 years ago. This extreme persisted for several thousand years.... , with continuing impact from human activity.
Present day	With a human population World population The world population is the total number of living humans on Earth at a given time. As of March 2009, the world's population is estimated to be about 6.76 1,000,000,000 .... approaching 6.76 billion, the impact of humanity is felt in all corners of the globe. Overfishing Overfishing Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans.... , anthropogenic Anthropogenic Anthropogenic effects, processes or materials are those that are derived from human activities, as opposed to those occurring in natural environments without human influence.... climate change, industrialization Industrialization Industrialization is the process of social and economic change whereby a human group is transformed from a pre-industrial society into an industry one.... , intensive agriculture, clearance of rain forests and other activities contribute to a dramatically rising extinction rate. If current rates continue, humanity will have seen the eradication of one-half of Earth's biodiversity over the next hundred years.

External links

- explore complete phylogenetic tree interactively
at the TalkOrigins Archive
TalkOrigins Archive

The TalkOrigins Archive is a website that presents mainstream science perspectives on the antievolution claims of young-earth, old-earth, and "intelligent design" creationists....
from Planck Time to the lifespan of the universe
- from the University of Cambridge Ensemble Project

Timeline of evolution

Basic timeline

Detailed timeline

Hadean
Hadean

The Hadean is the Eon before the Archean. It started at Earth formation about 4.6 billion years ago , and ended roughly 3.8 billion years ago, though the latter date varies according to different sources....
eon

Archean
Archean

The Archean is a geology eon before the Proterozoic and Paleoproterozoic, before 2.5 Ga . Instead of being based on stratigraphy, this date is defined chronometrically....
eon

Proterozoic
Proterozoic

The Proterozoic is a eon representing a period before the first abundant complex life on Earth. The Proterozoic Eon extended from 2500 annum to 542.0 ? 1.0 Ma , and is the most recent part of the old, informally named ?Precambrian? time....
eon

Phanerozoic eon

Mesozoic
Mesozoic

The Mesozoic Era is one of three Geologic time scale of the Phanerozoic eon . The division of time into eras dates back to Giovanni Arduino, in the 18th century, although his original name for the era now called the 'Mesozoic' was 'Secondary' ....
era

Cenozoic
Cenozoic

The Cenozoic Era...
era

See also

Further reading

External links

Timeline of evolution

Basic timeline

Detailed timeline

HadeanHadeanThe Hadean is the Eon before the Archean. It started at Earth formation about 4.6 billion years ago , and ended roughly 3.8 billion years ago, though the latter date varies according to different sources.... eon

ArcheanArcheanThe Archean is a geology eon before the Proterozoic and Paleoproterozoic, before 2.5 Ga . Instead of being based on stratigraphy, this date is defined chronometrically.... eon

ProterozoicProterozoicThe Proterozoic is a eon representing a period before the first abundant complex life on Earth. The Proterozoic Eon extended from 2500 annum to 542.0 ? 1.0 Ma , and is the most recent part of the old, informally named ?Precambrian? time.... eon

Phanerozoic eon

MesozoicMesozoicThe Mesozoic Era is one of three Geologic time scale of the Phanerozoic eon . The division of time into eras dates back to Giovanni Arduino, in the 18th century, although his original name for the era now called the 'Mesozoic' was 'Secondary' .... era

CenozoicCenozoicThe Cenozoic Era... era

See also

Further reading

External links

Hadean
Hadean

The Hadean is the Eon before the Archean. It started at Earth formation about 4.6 billion years ago , and ended roughly 3.8 billion years ago, though the latter date varies according to different sources....
eon

Archean
Archean

The Archean is a geology eon before the Proterozoic and Paleoproterozoic, before 2.5 Ga . Instead of being based on stratigraphy, this date is defined chronometrically....
eon

Proterozoic
Proterozoic

The Proterozoic is a eon representing a period before the first abundant complex life on Earth. The Proterozoic Eon extended from 2500 annum to 542.0 ? 1.0 Ma , and is the most recent part of the old, informally named ?Precambrian? time....
eon

Mesozoic
Mesozoic

The Mesozoic Era is one of three Geologic time scale of the Phanerozoic eon . The division of time into eras dates back to Giovanni Arduino, in the 18th century, although his original name for the era now called the 'Mesozoic' was 'Secondary' ....
era

Cenozoic
Cenozoic

The Cenozoic Era...
era