Phanerozoic Eon is the current geologic eon in the geologic
time scale, and the one during which abundant animal and plant life
has existed. It covers 541 million years to the present, and began
Cambrian Period when diverse hard-shelled animals first
appeared. Its name was derived from the
Ancient Greek words
φανερός (phanerós) and ζωή (zōḗ), meaning visible life,
since it was once believed that life began in the Cambrian, the first
period of this eon. The time before the Phanerozoic, called the
Precambrian supereon, is now divided into the Hadean, Archaean and
The time span of the
Phanerozoic starts with what appears to be the
rapid emergence of a number of animal phyla; the evolution of those
phyla into diverse forms; the emergence and development of complex
plants; the evolution of fish; the emergence of insects and tetrapods;
and the development of modern fauna.
Plant life on land appeared in
Phanerozoic eon. During this time span, tectonic forces
caused the continents to move and eventually collect into a single
landmass known as
Pangaea (the most recent supercontinent), which then
separated into the current continental landmasses.
2 Eras of the Phanerozoic
4 See also
7 External links
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Earliest Earth (−4540)
Earliest sexual reproduction
Axis scale: million years
Orange labels: ice ages.
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Phanerozoic boundary is at 541 million years
ago. In the 19th century, the boundary was set at time of
appearance of the first abundant animal (metazoan) fossils but several
hundred groups (taxa) of metazoa of the earlier
Proterozoic era have
been identified since the systematic study of those forms started in
the 1950s. Most geologists and paleontologists would probably set the
Phanerozoic boundary either at the classic point where the
first trilobites and reef-building animals (archaeocyatha) such as
corals and others appear; at the first appearance of a complex feeding
burrow called Treptichnus pedum; or at the first appearance of a group
of small, generally disarticulated, armored forms termed 'the small
shelly fauna'. The three different dividing points are within a few
million years of each other.
In the older literature, the term
Phanerozoic is generally used as a
label for the time period of interest to paleontologists, but that use
of the term seems to be falling into disuse in more modern literature.
Eras of the Phanerozoic
Phanerozoic is divided into three eras: the Paleozoic, Mesozoic,
and Cenozoic, which are further subdivided into 12 periods. The
Paleozoic features the rise of fish, amphibians and reptiles. The
Mesozoic is ruled by the reptiles, and features the evolution of
mammals, birds and more famously, dinosaurs. The
Cenozoic is the time
of the mammals, and more recently, humans.
Main article: Paleozoic
Paleozoic is a time in Earth's history when complex life forms
evolved, took their first breath of oxygen on dry land, and when the
forerunners of all life on Earth began to diversify. There are six
periods in the
Paleozoic era: Cambrian, Ordovician, Silurian,
Carboniferous and Permian.
Main article: Cambrian
Cambrian is the first period of the
Paleozoic Era and starts from
541 to 485 million years ago. The
Cambrian sparked a rapid
expansion in evolution in an event known as the
during which the greatest number of creatures evolved in a single
period in the history of Earth. Plants like algae evolved, and the
fauna was dominated by armored arthropods, such as trilobites. Almost
all marine phyla evolved in this period. During this time, the
Pannotia began to break up, most of which later
recombined into the super-continent Gondwana.
Main article: Ordovician
Cephalaspis, a jawless fish
Ordovician spans from 485 million years to 440 million years ago.
Ordovician was a time in Earth's history in which many species
still prevalent today evolved, such as primitive fish, cephalopods,
and coral. The most common forms of life, however, were trilobites,
snails and shellfish. More importantly, the first arthropods crept
ashore to colonize Gondwana, a continent empty of animal life. By the
end of the Ordovican,
Gondwana had moved from the equator to the South
Laurentia had collided with Baltica, closing the Iapetus
Ocean. The glaciation of
Gondwana resulted in a major drop in sea
level, killing off all life that had established along its coast.
Glaciation caused a snowball Earth, leading to the Ordovician-Silurian
extinction, during which 60% of marine invertebrates and 25% of
families became extinct. This is considered the first mass extinction
and the second deadliest in the history of Earth.
Main article: Silurian
Silurian spans from 440 million years to 415 million years ago,
which saw a warming from Snowball Earth. This period saw the mass
evolution of fish, as jaw-less fish became more numerous, jawed fish
evolved, and the first freshwater fish evolved, though arthropods,
such as sea scorpions, remained the apex predators. Fully terrestrial
life evolved, which included early arachnids, fungi, and centipedes.
The evolution of vascular plants (Cooksonia) allowed plants to gain a
foothold on land. These early terrestrial plants are the forerunners
of all plant life on land. During this time, there were four
Gondwana (Africa, South America, Australia, Antarctica,
Laurentia (North America with parts of Europe),
rest of Europe), and
Siberia (Northern Asia). The recent rise in sea
levels provided new habitats for many new species.
Main article: Devonian
Eogyrinus (an amphibian) of the Carboniferous
Devonian spans from 415 million years to 360 million years ago.
Also known as the "Age of the Fish", the
Devonian features a huge
diversification in fish, including armored fish like
lobe-finned fish which eventually evolved into the first tetrapods. On
land, plant groups diversified incredibly in an event known as the
Devonian Explosion during which the first trees evolved, as well as
seeds. This event also allowed the diversification of arthropod life
as they took advantage of the new habitat. The first amphibians also
evolved, and the fish were now at the top of the food chain. Near the
end of the Devonian, 70% of all species became extinct in an event
known as the Late
Devonian extinction, which is the second mass
extinction known to have happened.
Main article: Carboniferous
Carboniferous spans from 360 million to 300 million years ago.
During this period, average global temperatures were exceedingly high:
Carboniferous averaged at about 20 degrees Celsius (but
cooled to 10 degrees during the Middle Carboniferous). Tropical
swamps dominated the Earth, and the large amounts of trees created
much of the carbon that became coal deposits (hence the name
Carboniferous). The high oxygen levels caused by these swamps allowed
massive arthropods, normally limited in size by their respiratory
systems, to proliferate. Perhaps the most important evolutionary
development of the time was the evolution of amniotic eggs, which
allowed amphibians to move farther inland and remain the dominant
vertebrates throughout the period. Also, the first reptiles and
synapsids evolved in the swamps. Throughout the Carboniferous, there
was a cooling pattern, which eventually led to the glaciation of
Gondwana as much of it was situated around the south pole, in an event
known as the Permo-
Carboniferous glaciation or the Carboniferous
Main article: Permian
Permian spans from 300 million to 250 million years ago and was
the last period of the
Paleozoic Era. At its beginning, all continents
came together to form the super-continent Pangaea, surrounded by one
ocean called Panthalassa. The Earth was very dry during this time,
with harsh seasons, as the climate of the interior of
regulated by large bodies of water. Reptiles and synapsids flourished
in the new dry climate. Creatures such as
Dimetrodon and Edaphosaurus
ruled the new continent. The first conifers evolved, then dominated
the terrestrial landscape. Nearing the end of the period, Scutosaurus
and gorgonopsids filled the empty desert. Eventually, they
disappeared, along with 95% of all life on Earth in an event simply
known as "the Great Dying", the world's third mass extinction event
and the largest in its history.
Main article: Mesozoic
Mesozoic ranges from 252 million to 66 million years ago. Also
known as "the Age of the dinosaurs", the
Mesozoic features the rise of
reptiles on their 150 million year conquest of the Earth on the land,
in the seas, and in the air. There are three periods in the Mesozoic:
Triassic, Jurassic, and Cretaceous.
Main article: Triassic
Triassic ranges from 250 million to 200 million years ago. The
Triassic is a desolate transitional time in Earth's history between
Extinction and the lush
Jurassic Period. It has three
major epochs: Early Triassic, Middle
Triassic and Late Triassic.
Triassic lasted between 250 million to 247 million years
ago, and was dominated by deserts as
Pangaea had not yet broken up,
thus the interior was arid. The Earth had just witnessed a massive
die-off in which 95% of all life became extinct. The most common life
on Earth were Lystrosaurus, labyrinthodonts, and
Euparkeria along with
many other creatures that managed to survive the Great Dying.
Temnospondyli evolved during this time and would be the dominant
predator for much of the Triassic.
Plateosaurus (a prosauropod)
Triassic spans from 247 million to 237 million years ago.
Triassic featured the beginnings of the breakup of Pangaea,
and the beginning of the Tethys Sea. The ecosystem had recovered from
the devastation of the Great Dying. Phytoplankton, coral, and
crustaceans all had recovered, and the reptiles began increasing in
size. New aquatic reptiles, such as ichthyosaurs and nothosaurs,
evolved. Meanwhile, on land, pine forests flourished, as well as
mosquitoes and fruit flies. The first ancient crocodilians evolved,
which sparked competition with the large amphibians that had long
ruled the freshwater world.
Triassic spans from 237 million to 200 million years ago.
Following the bloom of the Middle Triassic, the Late
frequent rises of temperature, as well as moderate precipitation
(10-20 inches per year). The recent warming led to a boom of reptilian
evolution on land as the first true dinosaurs evolved, as well as
pterosaurs. The climactic change, however, resulted in a large die-out
known as the Triassic-
Jurassic extinction event, in which all
archosaurs (excluding ancient crocodiles), synapsids, and almost all
large amphibians became extinct, as well as 34% of marine life in the
fourth mass extinction event. The extinction's cause is
Main article: Jurassic
Jurassic ranges from 200 million to 145 million years ago, and
features three major epochs: Early Jurassic, Middle Jurassic, and Late
Jurassic Epoch spans from 200 million to
175 million years ago. The climate was much more humid than
the Triassic, and as a result, the world was very tropical. In the
oceans, plesiosaurs, ichthyosaurs and ammonites dominanted the seas.
On land, dinosaurs and other reptiles dominated the land, with species
Dilophosaurus at the apex. The first true crocodiles evolved,
pushing the large amphibians to near extinction. The reptiles rose to
rule the world. Meanwhile, the first true mammals evolved, but never
exceeded the height of a shrew.
Jurassic Epoch spans from 175 million to
163 million years ago. During this epoch, reptiles flourished
as huge herds of sauropods, such as
Brachiosaurus and Diplodicus,
filled the fern prairies of the Middle Jurassic. Many other predators
rose as well, such as Allosaurus. Conifer forests made up a large
portion of the world's forests. In the oceans, plesiosaurs were quite
common, and ichthyosaurs were flourishing. This epoch was the peak of
Artist’s 1901 depiction of a
Stegosaurus (inaccurately portrayed
with a dragging tail).
Jurassic Epoch spans from 163 million to
145 million years ago. The Late
Jurassic featured a massive
extinction of sauropods and ichthyosaurs due to the separation of
Gondwana in an extinction known as the
Cretaceous extinction. Sea levels rose, destroying fern
prairies and creating shallows. Ichthyosaurs became extinct whereas
sauropods, as a whole, did not; in fact, some species, like
Titanosaurus, lived until the K-T extinction. The increase in
sea-levels opened up the Atlantic sea way which would continue to get
larger over time. The divided world would give opportunity for the
diversification of new dinosaurs.
Main article: Cretaceous
Cretaceous is the longest period in the Mesozoic, spans from 145
million to 66 million years ago, and is divided into two epochs: Early
Cretaceous, and Late Cretaceous.
Tylosaurus (a mosasaur) hunting Xiphactinus
Cretaceous Epoch spans from 145 million to 100 million years
ago. The Early
Cretaceous saw the expansion of seaways, and as a
result, the decline and extinction of sauropods (except in South
America). Many coastal shallows were created, and that caused
ichthyosaurs to die out.
Mosasaurs evolved to replace them as apex
species of the seas. Some island-hopping dinosaurs, like
Eustreptospondylus, evolved to cope with the coastal shallows and
small islands of ancient Europe. Other dinosaurs, such as
Carcharodontosaurus and Spinosaurus, rose to fill the empty space that
Cretaceous extinction had created. Of the most successful
would be the
Iguanodon which spread to every continent. Seasons came
back into effect and the poles grew seasonally colder.
Leaellynasaura inhabited the polar forests year-round, while
many dinosaurs, such as the Muttaburrasaurus, migrated there during
summer . Since it was too cold for crocodiles, it was the last
stronghold for large amphibians, such as the Koolasuchus. Pterosaurs
grew larger as species like Tapejara and
Ornithocheirus evolved. More
importantly, the first true birds evolved sparking competition between
them and the pterosaurs.
Cretaceous Epoch spans from 100 million to 65 million years
ago. The Late
Cretaceous featured a cooling trend that would
continue into the
Cenozoic Era. Eventually, tropical ecology was
restricted to the equator and areas beyond the tropic lines featured
extreme seasonal changes of weather.
Dinosaurs still thrived as new
species such as Tyrannosaurus, Ankylosaurus,
Hadrosaurs dominated the food web. Pterosaurs, however, were going
into a decline as birds took to the skies. The last pterosaur to die
off was Quetzalcoatlus. Marsupials evolved within the large conifer
forests as scavengers. In the oceans,
Mosasaurs ruled the seas to fill
the role of the ichthyosaurs, and huge plesiosaurs, such as
Elasmosaurus, evolved. Also, the first flowering plants evolved. At
the end of the Cretaceous, the
Deccan Traps and other volcanic
eruptions were poisoning the atmosphere. As this was continued, it is
thought that a large meteor smashed into Earth, creating the Chicxulub
Crater creating the event known as the K-T Extinction, the fifth and
most recent mass extinction event, during which 75% of life on Earth
became extinct, including all non-avian dinosaurs. Every living thing
with a body mass over 10 kilograms became extinct, and the age of the
dinosaurs came to an end.
Main article: Cenozoic
Cenozoic featured the rise of mammals as the dominant class of
animals, as the end of the age of the dinosaurs left significant
evolutionary vacuums. There are three divisions of the Cenozoic:
Neogene and Quaternary.
Main article: Paleogene
Paleogene spans from the extinction of the dinosaurs, some 66
million years ago, to the dawn of the
Neogene 23 million years ago. It
features three epochs: Paleocene,
Eocene and Oligocene.
Basilosaurus (a whale, despite the name)
Paleocene Epoch began with the
K-T extinction event caused by the
impact of a metorite in the area of present-day
Yucatan Peninsula and
caused the destruction of 75% of all species on Earth. The Early
Paleocene saw the recovery of the Earth from that event. The
continents began to take their modern shape, but all continents (and
India) were separated from each other.
Afro-Eurasia was separated by
the Tethys Sea, and the Americas were separated by the strait of
Panama, as the Isthmus of Panama had not yet formed. This epoch
featured a general warming trend, and jungles eventually reached the
poles. The oceans were dominated by sharks as the large reptiles that
had once ruled became extinct. Archaic mammals, such as creodonts and
early primates that evolved during the
Mesozoic filled the world.
During this time there were no land creatures over 10 kilograms.
Mammals were still quite small.
Eocene Epoch ranged from 56 million to 34 million years ago. In
the early Eocene, land animals were small and living in cramped
jungles, much like the Paleocene. None had a mass over 10
kilograms. Among them were early primates, whales and horses along
with many other early forms of mammals. At the top of the food chains
were huge birds, such as Gastornis. It is the only time in recorded
history that birds ruled the world (excluding their ancestors, the
dinosaurs). The temperature was 30 degrees Celsius with little
temperature gradient from pole to pole. In the Middle
the circum-Antarctic current between Australia and Antarctica formed
which disrupted ocean currents worldwide, resulting in global cooling,
and caused the jungles to shrink. This allowed mammals to grow; some
such as whales to mammoth proportions, which were, by now, almost
fully aquatic. Mammals like
Andrewsarchus were now at the top of the
food-chain and sharks were replaced by Basilosaurus, whales, as rulers
of the seas. The late
Eocene Epoch saw the rebirth of seasons, which
caused the expansion of savanna-like areas, along with the evolution
Oligocene Epoch spans from 33 million to 23 million years ago. The
Oligocene featured the expansion of grass which had led to many new
species to take advantage, including the first elephants, cats, dogs,
marsupials and many other species still prevalent today. Many other
species of plants evolved during this epoch also, such as the
evergreen trees. The long term cooling continued and seasonal rains
patterns established. Mammals continued to grow larger.
Paraceratherium, the largest land mammal to ever live evolved during
this epoch, along with many other perissodactyls in an event known as
Oligocene extinction event (Grand Coupure).
Main article: Neogene
Animals of the
Miocene (Chalicotherium, Hyenadon, entelodont)
Neogene spans from 23.03 million to 2.58 million years ago. It
features 2 epochs: the Miocene, and the Pliocene.
Miocene spans from 23.03 to 5.333 million years ago and is a
period in which grass spread further across, effectively dominating a
large portion of the world, diminishing forests in the process. Kelp
forests evolved, leading to the evolution of new species, such as sea
otters. During this time, perissodactyla thrived, and evolved into
many different varieties. Alongside them were the apes, which evolved
into a 30 species. Overall, arid and mountainous land dominated most
of the world, as did grazers. The
Tethys Sea finally closed with the
creation of the Arabian Peninsula and in its wake left the Black, Red,
Mediterranean and Caspian Seas. This only increased aridity. Many new
plants evolved, and 95% of modern seed plants evolved in the
Pliocene lasted from 5.333 to 2.58 million years ago. The Pliocene
featured dramatic climactic changes, which ultimately led to modern
species and plants. The Mediterranean Sea dried up for several million
years. Along with these major geological events, Australopithecus
evolved in Africa, beginning the human branch. The isthmus of Panama
formed, and animals migrated between North and South America, wreaking
havoc on the local ecology. Climatic changes brought savannas that are
still continuing to spread across the world, Indian monsoons, deserts
in East Asia, and the beginnings of the Sahara desert. The Earth's
continents and seas moved into their present shapes. The world map has
not changed much since, save for changes brought about by the
glaciations of the Quaternary, such as the Great Lakes.
Main article: Quaternary
Quaternary spans from 2.58 million years ago to present day, and
is the shortest geological period in the
Phanerozoic Eon. It features
modern animals, and dramatic changes in the climate. It is divided
into two epochs: the
Pleistocene and the Holocene.
Megafauna of the
Pleistocene (mammoths, cave lions, woolly rhino,
Pleistocene lasted from 2.58 million to 11,700 years ago. This
epoch was marked by ice ages as a result of the cooling trend that
started in the Mid-Eocene. There were at least four separate
glaciation periods marked by the advance of ice caps as far south as
40 degrees N latitude in mountainous areas. Meanwhile, Africa
experienced a trend of desiccation which resulted in the creation of
the Sahara, Namib, and Kalahari deserts. Many animals evolved
including mammoths, giant ground sloths, dire wolves, saber-toothed
cats, and most famously Homo sapiens. 100,000 years ago marked the end
of one of the worst droughts of Africa, and led to the expansion of
primitive man. As the
Pleistocene drew to a close, a major extinction
wiped out much of the world's megafauna, including some of the hominid
species, such as Neanderthals. All the continents were affected, but
Africa to a lesser extent. That continent retains many large animals,
such as hippos.
Holocene began 11,700 years ago and lasts until to present day.
All recorded history and "the history of the world" lies within the
boundaries of the
Human activity is blamed for a
mass extinction that began roughly 10,000 years ago, though the
species becoming extinct have only been recorded since the Industrial
Revolution. This is sometimes referred to as the "Sixth Extinction".
More than 322 species have become extinct due to human activity since
the Industrial Revolution.
During the Phanerozoic, biodiversity shows a steady but not monotonic
increase from near zero to several thousands of genera.
It has been demonstrated that changes in biodiversity through the
Phanerozoic correlate much better with the hyperbolic model (widely
used in demography and macrosociology) than with exponential and
logistic models (traditionally used in population biology and
extensively applied to fossil biodiversity as well). The latter models
imply that changes in diversity are guided by a first-order positive
feedback (more ancestors, more descendants) or a negative feedback
that arises from resource limitation, or both. The hyperbolic model
implies a second-order positive feedback. The hyperbolic pattern of
the human population growth arises from a second-order positive
feedback, caused by the interaction of the population size and the
rate of technological growth. The character of biodiversity growth
Phanerozoic Eon can be similarly accounted for by a feedback
between the diversity and community structure complexity. It is
suggested that the similarity between the curves of biodiversity and
human population probably comes from the fact that both are derived
from the superposition on the hyperbolic trend of cyclical and random
^ "Phanerozoic". Oxford Dictionaries. Oxford University Press.
^ There are several ways of pronouncing Phanerozoic, including
/ˌfænərəˈzoʊɪk, ˌfænrə-, -roʊ-/.
^ Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X. (2013).
"International Chronostratigraphic Chart v 2015/01" (PDF). Episodes
36: 199-204. International Commission on Stratigraphy. Retrieved
Phanerozoic Eon geochronology". Encyclopedia Britannica.
^ University of California. "Paleozoic". University of
^ University of California. "Cambrian". University of
^ University of California. "Ordovician". University of
^ University of California. "Silurian". University of
^ University of California. "Devonian". University of
^ Monte Hieb. "
Carboniferous Era". unknown.
^ University of California. "Carboniferous". University of
^ Natural History Museum. "The Great Dying". Natural History
^ University of California. "
Permian Era". University of
^ Alan Logan. "Triassic". University of New Brunswick.
^ Alan Kazlev. "Early Triassic". unknown. Archived from the original
^ Rubidge. "Middle Triassic". unknown.
^ Graham Ryder; David Fastovsky & Stefan Gartner. "Late Triassic
Extinction". Geological Society of America.
^ Enchanted Learning. "Late
Triassic life". Enchanted Learning.
^ a b c d Carol Marie Tang. "
Jurassic Era". California Academy of
^ Alan Kazlev. "Early Jurassic". unknown.
^ Enchanted Learning. "Middle Jurassic". Enchanted Learning.
^ Bob Strauss. "
Cretaceous sauropods". author.
^ a b c Carl Fred Koch. "Cretaceous". Old Dominion University.
^ University of California. "Cretaceous". University of
^ Elizabeth Howell. "
K-T Extinction event". Universe Today.
^ Encyclopædia Britannica. "Paleocene". Encyclopædia
^ University of California. "
Eocene Epoch". University of
^ University of California. "
Eocene Climate". University of
^ National Geographic Society. "Eocene". National Geographic.
^ University of California. "Oligocene". University of
^ Encyclopædia Britannica. "Neogene". Encyclopædia Britannica.
^ University of California. "Miocene". University of California.
^ University of California. "Pliocene". University of
^ Jonathan Adams. "
Pliocene climate". Oak Ridge National Library.
Archived from the original on 2015-02-25.
^ University of California. "Pleistocene". University of
^ University of California. "Holocene". University of
^ Scientific American. "
Sixth Extinction extinctions". Scientific
^ IUCN. "Sixth Extinction". IUCN.
^ a b See, e. g., Markov, A.; Korotayev, A. (2008). "Hyperbolic growth
of marine and continental biodiversity through the
community evolution". Zhurnal Obshchei Biologii (Journal of General
Biology). 69 (3): 175–194.
Markov, Alexander V.; Korotayev, Andrey V. (2007). "
biodiversity follows a hyperbolic trend". Palaeoworld. 16 (4):
Miller, K. G.; Kominz, M. A.; Browning, J. V.; Wright, J. D.;
Mountain, G. S.; Katz, M. E.; Sugarman, P. J.; Cramer, B. S.;
Christie-Blick, N; Pekar, S. F.; et al. (2005). "The Phanerozoic
record of global sea-level change". Science. 310 (5752): 1293–1298.
Media related to
Phanerozoic at Wikimedia Commons
Geologic history of Earth
Quaternary (present–2.588 Mya)
Holocene (present–11.784 kya)
Pleistocene (11.784 kya–2.588 Mya)
Neogene (2.588–23.03 Mya)
Pliocene (2.588–5.333 Mya)
Miocene (5.333–23.03 Mya)
Paleogene (23.03–66.0 Mya)
Oligocene (23.03–33.9 Mya)
Eocene (33.9–56.0 Mya)
Paleocene (56.0–66.0 Mya)
Cretaceous (66.0–145.0 Mya)
Late (66.0–100.5 Mya)
Early (100.5–145.0 Mya)
Jurassic (145.0–201.3 Mya)
Late (145.0–163.5 Mya)
Middle (163.5–174.1 Mya)
Early (174.1–201.3 Mya)
Triassic (201.3–251.902 Mya)
Late (201.3–237 Mya)
Middle (237–247.2 Mya)
Early (247.2–251.902 Mya)
Permian (251.902–298.9 Mya)
Lopingian (251.902–259.8 Mya)
Guadalupian (259.8–272.3 Mya)
Cisuralian (272.3–298.9 Mya)
Carboniferous (298.9–358.9 Mya)
Pennsylvanian (298.9–323.2 Mya)
Mississippian (323.2–358.9 Mya)
Devonian (358.9–419.2 Mya)
Late (358.9–382.7 Mya)
Middle (382.7–393.3 Mya)
Early (393.3–419.2 Mya)
Silurian (419.2–443.8 Mya)
Pridoli (419.2–423.0 Mya)
Ludlow (423.0–427.4 Mya)
Wenlock (427.4–433.4 Mya)
Llandovery (433.4–443.8 Mya)
Ordovician (443.8–485.4 Mya)
Late (443.8–458.4 Mya)
Middle (458.4–470.0 Mya)
Early (470.0–485.4 Mya)
Cambrian (485.4–541.0 Mya)
Furongian (485.4–497 Mya)
Series 3 (497–509 Mya)
Series 2 (509–521 Mya)
Terreneuvian (521–541.0 Mya)
(541.0 Mya–2.5 Gya)
Neoproterozoic era (541.0 Mya–1 Gya)
Ediacaran (541.0-~635 Mya)
Cryogenian (~635-~720 Mya)
Tonian (~720 Mya-1 Gya)
Mesoproterozoic era (1–1.6 Gya)
Stenian (1-1.2 Gya)
Ectasian (1.2-1.4 Gya)
Calymmian (1.4-1.6 Gya)
Paleoproterozoic era (1.6–2.5 Gya)
Statherian (1.6-1.8 Gya)
Orosirian (1.8-2.05 Gya)
Rhyacian (2.05-2.3 Gya)
Siderian (2.3-2.5 Gya)
Archean eon² (2.5–4 Gya)
Neoarchean (2.5–2.8 Gya)
Mesoarchean (2.8–3.2 Gya)
Paleoarchean (3.2–3.6 Gya)
Eoarchean (3.6–4 Gya)
Hadean eon² (4–4.6 Gya)
kya = thousands years ago. Mya = millions years ago.
Gya = billions
years ago.¹ =
Phanerozoic eon. ² =
Source: (2017/02). International Commission on Stratigraphy. Retrieved
13 July 2015. Divisions of Geologic Time—Major Chronostratigraphic
and Geochronologic Units USGS Retrieved 10 March 2013.
Evolutionary history of life
Index of evolutionary biology articles
Outline of evolution
Timeline of evolution
Earliest known life forms
Evidence of common descent
Last universal common ancestor
Origin of life
Evolutionary developmental biology
dolphins and whales
Programmed cell death
Life cycles/nuclear phases
Tempo and modes
Renaissance and Enlightenment
Transmutation of species
On the Origin of Species
History of paleontology
The eclipse of Darwinism
History of molecular evolution
Extended evolutionary synthesis
Teleology in biology