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The Cenozoic ( ; ) is Earth's current geological
era An era is a span of time defined for the purposes of chronology 222px, Joseph Scaliger's ''De emendatione temporum'' (1583) began the modern science of chronology Chronology (from Latin Latin (, or , ) is a classical language belonging t ...
, representing the last 66million years of Earth's history. It is characterized by the dominance of
mammal Mammals (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be i ...
s,
bird Birds are a group of warm-blooded vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With ...

bird
s and
flowering plants The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of land plants The Embryophyta () or land plants are the most familiar group of green plants that form vegetation on earth. Embryophyta is a c ...

flowering plants
, a cooling and drying
climate Climate is the long-term pattern of weather Weather is the state of the atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a la ...

climate
, and the current configuration of continents. It is the latest of three geological eras since complex life evolved, preceded by the
Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles and the Age of Conifers, is the second-to-last era An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy ...
and
Paleozoic The Paleozoic (or Palaeozoic) Era ( ; from the Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its popula ...
. It started with the
Cretaceous–Paleogene extinction event The Cretaceous–Paleogene (K–Pg) extinction event (also known as the Cretaceous–Tertiary extinction) was a sudden of three-quarters of the and on , approximately 66 million years ago. With the exception of some species such as ...
, when many species, including the non-avian
dinosaurs Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 annum, million years ago, although the exact origin and timing of the evolution o ...

dinosaurs
, became extinct in an event attributed by most experts to the impact of a large asteroid or other celestial body, the
Chicxulub impactorChicxulub may refer to: * Chicxulub crater, on the Yucatán Peninsula, in Mexico * Chicxulub impactor, responsible for the K-Pg extinction of the dinosaurs * Chicxulub Pueblo, a town on the Yucatán Peninsula * Chicxulub Pueblo Municipality ...
. The Cenozoic is also known as the Age of Mammals because the terrestrial animals that dominated both hemispheres were
mammal Mammals (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be i ...
sthe eutherians (placentals) in the northern hemisphere and the metatherians (marsupials, now mainly restricted to Australia) in the southern hemisphere. The extinction of many groups allowed mammals and birds to greatly diversify so that large mammals and birds dominated the Earth. The continents also moved into their current positions during this era. The Earth's climate had begun a drying and cooling trend, culminating in the glaciations of the
Pleistocene Epoch The Pleistocene ( , often colloquially referred to as the ''Ice Age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the world's most recent period of repeated glaciations. Before a change finally confir ...
, and partially offset by the Paleocene-Eocene Thermal Maximum.


Nomenclature

''Cenozoic'' derives from the Greek words ( 'new') and ( 'life'). The name was proposed in 1840 by the British geologist
John Phillips
John Phillips
(1800–1874), who originally spelled it ''Kainozoic''. The era is also known as the ''Cænozoic'', ''Caenozoic'', or ''Cainozoic'' (). In name, the Cenozoic () is comparable to the preceding Mesozoic ('middle life') and Paleozoic ('old life') Eras, as well as to the Proterozoic ('earlier life') Eon.


Divisions

The Cenozoic is divided into three periods: the
Paleogene The Paleogene ( ; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous The Cretaceous ( ) is a geological period A geologi ...
,
Neogene The Neogene ( ) (informally Upper Tertiary or Late Tertiary) is a geologic period and system that spans 20.45 million years from the end of the Paleogene The Paleogene ( ; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Ea ...

Neogene
, and
Quaternary The Quaternary ( ) is the current and most recent of the three period (geology), periods of the Cenozoic era (geology), Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans ...
; and seven epochs: the
Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch In chronology 222px, Joseph Scaliger's ''De emendatione temporum'' (1583) began the modern science of chronology Chronology (from Latin Latin (, or , ) is a classical language bel ...
,
Eocene The Eocene ( ) Epoch is a geological epoch In chronology 222px, Joseph Scaliger's ''De emendatione temporum'' (1583) began the modern science of chronology Chronology (from Latin Latin (, or , ) is a classical language belonging to the ...
,
Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define ...
,
Miocene The Miocene ( ) is the first Epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; its name comes from the Greek words (', "less") and (', "new") and mean ...
,
Pliocene The Pliocene ( ; also Pleiocene) epoch (geology), Epoch is the epoch in the geologic timescale that extends from 5.333 million to 2.58Pleistocene The Pleistocene ( , often referred to as the ''Ice Age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the earth’s most recent period of repeated glaciations. Before a change finally ...
, and
Holocene The Holocene ( ) is the current geological epoch In geochronology, an epoch is a subdivision of the geologic timescale that is longer than an age (geology), age but shorter than a period (geology), period. The current epoch is the Holocene E ...
. The Quaternary Period was officially recognized by the
International Commission on Stratigraphy The International Commission on Stratigraphy (ICS), sometimes referred to unofficially as the "International Stratigraphic Commission", is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigr ...
in June 2009. In 2004, the
Tertiary Period Tertiary ( ) is a widely used, but obsolete term for the geologic period A geological period is one of the several subdivisions of geologic time enabling cross-referencing of rocks and geologic events from place to place. These periods form eleme ...
was officially replaced by the Paleogene and Neogene Periods. The common use of epochs during the Cenozoic helps
paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene The Holocene ( ) is the current Geologic time scale, geological epoch. ...
s better organize and group the many significant events that occurred during this comparatively short interval of time. Knowledge of this era is more detailed than any other era because of the relatively young, well-preserved rocks associated with it.


Paleogene

The Paleogene spans from the extinction of non-avian dinosaurs, 66 million years ago, to the dawn of the Neogene, 23.03 million years ago. It features three
epoch In chronology 222px, Joseph Scaliger's ''De emendatione temporum'' (1583) began the modern science of chronology Chronology (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-E ...
s: the
Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch In chronology 222px, Joseph Scaliger's ''De emendatione temporum'' (1583) began the modern science of chronology Chronology (from Latin Latin (, or , ) is a classical language bel ...
,
Eocene The Eocene ( ) Epoch is a geological epoch In chronology 222px, Joseph Scaliger's ''De emendatione temporum'' (1583) began the modern science of chronology Chronology (from Latin Latin (, or , ) is a classical language belonging to the ...
and
Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define ...
. The Paleocene Epoch lasted from 66 million to 56 million years ago. Modern placental mammals originated during this time. The Paleocene is a transitional point between the devastation that is the K–Pg extinction event, and the rich jungle environment that is the Early Eocene. The Early Paleocene saw the recovery of the earth. The continents began to take their modern shape, but all the continents and the subcontinent of India were separated from each other.
Afro-Eurasia Afro-Eurasia (or Afroeurasia, Field, Henry.The University of California African Expedition: I, Egypt, ''American Anthropologist,'' New Series Vol. 50, No. 3, Part 1 (Jul. - Sep., 1948), pp. 479-493. or Eurafrasia), nicknamed the World Island, ...

Afro-Eurasia
was separated by the
Tethys Sea 250px, First phase of the Tethys Ocean's forming: the (first) Tethys Sea starts dividing Pangaea into two supercontinents, Laurasia and Gondwana">Laurasia.html" ;"title="Pangaea into two supercontinents, Laurasia">Pangaea into two supercontinents, ...
, and the Americas were separated by the strait of Panama, as the isthmus had not yet formed. This epoch featured a general warming trend, with jungles eventually reaching the poles. The oceans were dominated by sharks as the large reptiles that had once predominated were extinct. Archaic mammals filled the world such as creodonts (extinct carnivores, unrelated to existing
Carnivora Carnivora is an order of placental Placentalia is one of the three extant subdivisions of the class of animals Mammalia Mammals (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch ...
). The
Eocene Epoch The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' ...
ranged from 56 million years to 33.9 million years ago. In the Early-Eocene, species living in dense forest were unable to evolve into larger forms, as in the Paleocene. All known mammals were under 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 Paracrax. The temperature was 30 degrees Celsius with little temperature gradient from pole to pole. In the Mid-Eocene, the Circumpolar-Antarctic current between Australia and Antarctica formed. This disrupted ocean currents worldwide and as a result caused a global cooling effect, shrinking the jungles. This allowed mammals to grow to mammoth proportions, such as whales which, by that time, had become almost fully aquatic. Mammals like ''
Andrewsarchus ''Andrewsarchus'' () is an extinct genus of mammal that lived during the middle Eocene epoch in what is now Inner Mongolia, China. Only one species is usually recognized, ''A. mongoliensis'', known from a single skull of great size discovered in ...
'' were at the top of the food-chain. The Late Eocene saw the rebirth of seasons, which caused the expansion of savanna-like areas, along with the evolution of
grass Poaceae () or Gramineae () is a large and nearly ubiquitous family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relationship). The purpose of families is to maintain ...

grass
. The end of the Eocene was marked by the Eocene-Oligocene extinction event, the European face of which is known as the
Grande Coupure
Grande Coupure
. The Oligocene Epoch spans from 33.9 million to 23.03 million years ago. The Oligocene featured the expansion of
grass Poaceae () or Gramineae () is a large and nearly ubiquitous family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relationship). The purpose of families is to maintain ...

grass
which had led to many new species to evolve, including the first elephants, cats, dogs, marsupials and many other species still prevalent today. Many other species of plants evolved in this period too. A cooling period featuring seasonal rains was still in effect. Mammals still continued to grow larger and larger.


Neogene

The Neogene spans from 23.03 million to 2.58 million years ago. It features 2 epochs: the Miocene, and the Pliocene. The
Miocene Epoch The Miocene ( ) is the first Epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish author Charles Lyell; its name comes from the Greek words (', "less") and (', "new") and means "le ...
spans from 23.03 to 5.333 million years ago and is a period in which
grass Poaceae () or Gramineae () is a large and nearly ubiquitous family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relationship). The purpose of families is to maintain ...

grass
spread further, dominating a large portion of the world, at the expense of forests.
Kelp Kelps are large brown algae The brown algae (singular: alga), comprising the class (biology), class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Most b ...

Kelp
forests evolved, encouraging the evolution of new species, such as
sea otter The sea otter (''Enhydra lutris'') is a marine mammal native to the coasts of the northern and eastern Pacific Ocean, North Pacific Ocean. Adult sea otters typically weigh between , making them the heaviest members of the Mustelidae, weasel fam ...

sea otter
s. During this time, perissodactyla thrived, and evolved into many different varieties.
Apes Apes (Hominoidea ) are a branch The branches and leaves of a tree. A branch ( or , ) or tree branch (sometimes referred to in botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of b ...
evolved into 30 species. The
Tethys Sea 250px, First phase of the Tethys Ocean's forming: the (first) Tethys Sea starts dividing Pangaea into two supercontinents, Laurasia and Gondwana">Laurasia.html" ;"title="Pangaea into two supercontinents, Laurasia">Pangaea into two supercontinents, ...
finally closed with the creation of the
Arabian Peninsula The Arabian Peninsula (; ar, شِبْهُ الْجَزِيرَةِ الْعَرَبِيَّة, , "Arabian Peninsula" or , , "Island of the Arabs") is a peninsula of Western Asia, situated northeast of Africa on the Arabian Plate. At , the ...
, leaving only remnants as the
Black Black is a color which results from the absence or complete absorption Absorption may refer to: Chemistry and biology *Absorption (chemistry), diffusion of particles of gas or liquid into liquid or solid materials *Absorption (skin), a rout ...

Black
,
Red Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength Image:dominant wavelength.png, frame, Dominant/complementary wavelength example on the CIE color ...

Red
,
Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western Europe, Western and Southern Europe and Anatolia, on the south by North Africa ...
and
Caspian Sea The Caspian Sea (also known as Mazandaran Sea, Hyrcanian Ocean, or Khazar Sea), tk, Hazar deňzi, az, Xəzər Dənizi, russian: Каспийское море, script=Latn, fa, دریای مازندران، دریای خزر, script=Latn, tly, ...

Caspian Sea
s. This increased aridity. Many new plants evolved: 95% of modern
seed plants The spermatophytes (; ), also known as phanerogams (taxon Phanerogamae) or phaenogams (taxon Phaenogamae), comprise those plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to E ...
evolved in the mid-Miocene. The Pliocene Epoch lasted from 5.333 to 2.58 million years ago. The Pliocene featured dramatic climatic changes, which ultimately led to modern species of flora and fauna. The Mediterranean Sea dried up for several million years (because the
ice age An ice age is a long period of reduction in the temperature of Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents an ...

ice age
s reduced sea levels, disconnecting the
Atlantic
Atlantic
from the Mediterranean, and evaporation rates exceeded inflow from rivers). ''
Australopithecus ''Australopithecus'' (, ; ; singular: australopith) is a genus of early hominins that existed in Africa during the Late Pliocene and Early Pleistocene. The genera ''Homo'' (which includes modern humans), ''Paranthropus'', and ''Kenyanthropus'' ev ...

Australopithecus
'' evolved in
Africa Africa is the world's second-largest and second-most populous continent A continent is any of several large landmass A landmass, or land mass, is a large region In geography Geography (from Greek: , ''geographia'', ...

Africa
, beginning the human branch. The
isthmus of Panama The Isthmus of Panama ( es, Istmo de Panamá), also historically known as the Isthmus of Darien (), is the narrow strip of land that lies between the Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lamè Kara ...
formed, and animals migrated between
North North is one of the four compass points The points of the compass are the vectors by which planet A planet is an astronomical body orbiting a star or Stellar evolution#Stellar remnants, stellar remnant that is massive enough to be Hydro ...

North
and
South America South America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continent ...

South America
during the
great American interchange The Great American Biotic Interchange (commonly abbreviated as GABI), also known as the Great American Interchange or Great American Faunal Interchange, was an important late Cenozoic The Cenozoic ( ; ) is Earth's current geological era An era ...
, wreaking havoc on local ecologies. Climatic changes brought:
savanna A savanna or savannah is a mixed woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the ' woods), a low-density forming open s with plenty of sunlight and li ...

savanna
s that are still continuing to spread across the world; Indian
monsoon A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation In meteorology Meteorology is a branch of the (which include and ), with a major focus on . The study of meteorology ...

monsoon
s;
desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to the processes of ...

desert
s in central
Asia Asia () is Earth's largest and most populous continent, located primarily in the Eastern Hemisphere, Eastern and Northern Hemisphere, Northern Hemisphere of the Earth, Hemispheres. It shares the continental landmass of Eurasia with the cont ...

Asia
; and the beginnings of the
Sahara The Sahara (, ; ar, الصحراء الكبرى, ', 'the Greatest Desert') is a desert on the African continent Africa is the world's second-largest and second-most populous continent A continent is any of several large landma ...

Sahara
desert. The world map has not changed much since, save for changes brought about by the glaciations of the Quaternary, such as the
Great Lakes The Great Lakes also called the Great Lakes of North America or the Laurentian Great Lakes, is a series of large interconnected freshwater lake A lake is an area filled with water, localized in a basin, surrounded by land Land ...

Great Lakes
,
Hudson Bay Hudson Bay ( iu, text=ᑲᖏᖅᓱᐊᓗᒃ ᐃᓗᐊ, translit=Kangiqsualuk ilua or iu, text=ᑕᓯᐅᔭᕐᔪᐊᖅ, translit=Tasiujarjuaq; french: baie d'Hudson), sometimes called Hudson's Bay (usually historically), is a large body of sal ...
, and the
Baltic sea The Baltic Sea is an arm of the Atlantic Ocean, enclosed by Denmark Denmark ( da, Danmark, ) is a Nordic country The Nordic countries, or the Nordics, are a geographical and cultural region In geography, regions are areas that a ...

Baltic sea
.


Quaternary

The
Quaternary The Quaternary ( ) is the current and most recent of the three period (geology), periods of the Cenozoic era (geology), Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans ...
spans from 2.58 million years ago to present day, and is the shortest geological period in the
Phanerozoic Eon The Phanerozoic Eon is the current geologic eon in the geologic time scale The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontolo ...
. It features modern animals, and dramatic changes in the climate. It is divided into two epochs: the Pleistocene and the Holocene. The
Pleistocene The Pleistocene ( , often referred to as the ''Ice Age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the earth’s most recent period of repeated glaciations. Before a change finally ...
lasted from 2.58 million to 11,700 years ago. This epoch was marked by
ice ages#REDIRECT Ice age {{Redirect category shell, 1= {{R from move {{R from ambiguous term {{R from other capitalisation {{R unprintworthy ...
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° N in mountainous areas. Meanwhile, Africa experienced a trend of
desiccation Desiccation (from Latin de- "thoroughly" + siccare "to dry") is the state of extreme dryness, or the process of extreme drying Drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid ...
which resulted in the creation of the
Sahara The Sahara (, ; ar, الصحراء الكبرى, ', 'the Greatest Desert') is a desert on the African continent Africa is the world's second-largest and second-most populous continent A continent is any of several large landma ...

Sahara
,
Namib The Namib (; pt, Namibe) is a coastal desert upright=1.5, alt=see caption, Sand dunes in the Rub' al Khali ("Empty quarter") in the United Arab Emirates">Rub'_al_Khali.html" ;"title="Sand dunes in the Rub' al Khali">Sand dunes in the ...

Namib
, and
Kalahari The Kalahari Desert is a large semi-arid A semi-arid climate, semi-desert climate, or steppe climate is the climate Climate is the long-term pattern of weather Weather is the state of the atmosphere An atmosphere (from the ...
deserts. Many animals evolved including
mammoth A mammoth is any species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organ ...

mammoth
s,
giant ground sloths ''Megatherium'' ( from the Greek language, Greek ''Mega-, mega'' έγας meaning "great", and ''therion (disambiguation), therion'' ηρίον "beast") is an extinct genus of ground sloths endemic to South America that lived from the E ...
,
dire wolves The dire wolf (''Aenocyon dirus''From Greek αἰνός (ainós) 'dreadful' + κύων (kúōn) 'dog' and Latin ''dīrus'' 'fearsome' ) is an extinct canine. It is one of the most famous prehistoric carnivore A carnivore , meaning "meat ...
, saber-toothed cats, and most famously ''
Homo sapiens Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedality, bipedalism and large, complex brains. This has enabled the development of advanced tools, culture, and language. Humans are highl ...

Homo sapiens
''. 100,000 years ago marked the end of one of the worst droughts in Africa, and led to the expansion of primitive humans. 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
Neanderthal Neanderthals (, also Neandertals, ''Homo neanderthalensis'' or ''Homo sapiens neanderthalensis'') are an extinct species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an org ...
s. All the continents were affected, but Africa to a lesser extent. It still retains many large animals, such as hippos. The
Holocene The Holocene ( ) is the current geological epoch In geochronology, an epoch is a subdivision of the geologic timescale that is longer than an age (geology), age but shorter than a period (geology), period. The current epoch is the Holocene E ...
began 11,700 years ago and lasts to the present day. All recorded history and "the
Human history Human history, or world history, is the narrative of humanity Humanity most commonly refers to: * Human Humans (''Homo sapiens'') are the most populous and widespread species of primates, characterized by bipedality, opposable thumbs, ...
" lies within the boundaries of the Holocene Epoch. 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 The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe Continental Europe or mainland Europe is the contiguous continent A continent is any of several large landmasse ...
. This is sometimes referred to as the "
Sixth Extinction The Holocene extinction, otherwise referred to as the sixth mass extinction or Anthropocene extinction, is an ongoing extinction event of species during the present Holocene epoch (geology), epoch (with the more recent time sometimes called Anthro ...
". It is often cited that over 322 recorded species have become extinct due to human activity since the Industrial Revolution, but the rate may be as high as 500 vertebrate species alone, the majority of which have occurred after 1900.


Tectonics

Geologically Geology (from the Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following peri ...

Geologically
, the Cenozoic is the era when the
continent A continent is any of several large landmass A landmass, or land mass, is a large region In geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of science devoted to the study of th ...

continent
s moved into their current positions.
Australia-New Guinea The continent of Australia, sometimes known in technical contexts by the names Sahul (), Australinea, or Meganesia to distinguish it from the Australia, country of Australia, consists of the landmasses which sit on Australia's plate tecton ...
, having split from
Pangea Pangaea or Pangea () was a supercontinent In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology) ...

Pangea
during the early
Cretaceous The Cretaceous ( ) is a geological period A geological period is one of the several subdivisions of geologic time enabling cross-referencing of rocks and geologic events from place to place. These periods form elements of a hierarchy of division ...

Cretaceous
, drifted north and, eventually, collided with
South-east Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern subregion of Asia, consisting of the regions ...
;
Antarctica Antarctica ( or ) is Earth's southernmost continent. It contains the geographic South Pole and is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Oc ...

Antarctica
moved into its current position over the
South Pole The South Pole, also known as the Geographic South Pole, Terrestrial South Pole or 90th Parallel South, is one of the two points where Earth's axis of rotation intersects its surface. It is the southernmost point on Earth and lies on the ...
; the
Atlantic Ocean
Atlantic Ocean
widened and, later in the era (2.8 million years ago),
South America South America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continent ...

South America
became attached to
North America North America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continen ...

North America
with the
isthmus of Panama The Isthmus of Panama ( es, Istmo de Panamá), also historically known as the Isthmus of Darien (), is the narrow strip of land that lies between the Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lamè Kara ...
. India collided with Asia creating the Himalayas; Arabia collided with Eurasia, closing the
Tethys Ocean The Tethys Ocean ( el, Τηθύς ''Tēthús''), also called the Tethys Sea or the Neo-Tethys, was an ocean during much of the Era located between the ancient continents of and , before the opening of the and oceans during the Period. Etym ...
and creating the Zagros Mountains, around . The break-up of Gondwana in
Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous The Cretaceous ( ) is a that lasted from about 145 to 66 (Mya). It is the third and final period of the , as well as the longest. At around 79 millio ...
and Cenozoic times led to a shift in the river courses of various large African rivers including the Congo,
Niger ) , official_languages = French , languages_type = National language A national language is a language A language is a structured system of communication used by humans, including speech (spoken language), gestures (Signed languag ...

Niger
,
Nile The Nile, , Bohairic , lg, Kiira , Nobiin Nobiin, or Mahas, is a Northern Nubian languages, Nubian language of the Nilo-Saharan languages, Nilo-Saharan language family. "Nobiin" is the genitive case, genitive form of ''Nòòbíí'' ("Nub ...

Nile
,
Orange Orange most often refers to: *Orange (colour), occurs between red and yellow in the visible spectrum *Orange (fruit), the fruit of the tree species '' Citrus'' × ''sinensis'' ** Orange blossom, its fragrant flower *Some other citrus or citrus-li ...
,
Limpopo Limpopo is the northernmost Provinces of South Africa, province of South Africa. It is named after the Limpopo River, which forms the province's western and northern borders. The capital and largest city in the province is Polokwane (formerly ...
and
Zambezi The Zambezi River (also spelled Zambeze and Zambesi) is the List of rivers by length, fourth-longest river in Africa, the longest east-flowing river in Africa and the largest flowing into the Indian Ocean from Africa. The area of its drainage ba ...

Zambezi
.


Climate

In the Cretaceous, the climate was hot and humid with lush forests at the poles, there was no permanent ice and sea levels were around 300 metres higher than today. This continued for the first 10 million years of the Paleocene, culminating in the
Paleocene–Eocene Thermal Maximum The Paleocene–Eocene Thermal Maximum (PETM), alternatively (ETM1), and formerly known as the "Initial Eocene" or "", was a time period with a more than 5–8 °C global average temperature rise across the event. This climate event o ...
about . Around the earth entered a period of long term cooling. This was mainly due to the collision of India with Eurasia, which caused the rise of the
Himalayas The Himalayas, or Himalaya (; Sanskrit Sanskrit (; attributively , ; nominalization, nominally , , ) is a classical language of South Asia that belongs to the Indo-Aryan languages, Indo-Aryan branch of the Indo-European languages. It ar ...

Himalayas
: the upraised rocks eroded and reacted with in the air, causing a long-term reduction in the proportion of this greenhouse gas in the atmosphere. Around permanent ice began to build up on Antarctica. The cooling trend continued in the
Miocene The Miocene ( ) is the first Epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; its name comes from the Greek words (', "less") and (', "new") and mean ...
, with relatively short warmer periods. When South America became attached to North America creating the
Isthmus of Panama The Isthmus of Panama ( es, Istmo de Panamá), also historically known as the Isthmus of Darien (), is the narrow strip of land that lies between the Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lamè Kara ...
around , the Arctic region cooled due to the strengthening of the
HumboldtHumboldt may refer to: People * Alexander von Humboldt, German natural scientist, brother of Wilhelm von Humboldt * Wilhelm von Humboldt, German linguist, philosopher, and diplomat, brother of Alexander von Humboldt Fictional characters * Hum ...
and
Gulf Stream The Gulf Stream, together with its northern extension the North Atlantic Drift The North Atlantic Current (NAC), also known as North Atlantic Drift and North Atlantic Sea Movement, is a powerful warm western boundary current Boundary curren ...
currents, eventually leading to the glaciations of the
Quaternary ice age The Quaternary glaciation, also known as the Pleistocene glaciation, is an alternating series of glacial period, glacial and interglacial, interglacial periods during the Quaternary period that began 2.58 Year#SI prefix multipliers, Ma (million ...
, the current
interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial period A glacial period (alternatively glacial or ...
of which is the
Holocene The Holocene ( ) is the current geological epoch In geochronology, an epoch is a subdivision of the geologic timescale that is longer than an age (geology), age but shorter than a period (geology), period. The current epoch is the Holocene E ...
Epoch. Recent analysis of the geomagnetic reversal frequency, oxygen isotope record, and tectonic plate subduction rate, which are indicators of the changes in the heat flux at the core mantle boundary, climate and plate tectonic activity, shows that all these changes indicate similar rhythms on million years' timescale in the Cenozoic Era occurring with the common fundamental periodicity of ∼13 Myr during most of the time.


Life

Early in the Cenozoic, following the K-Pg event, the planet was dominated by relatively small fauna, including small mammals, birds, reptiles, and amphibians. From a geological perspective, it did not take long for mammals and birds to greatly diversify in the absence of the dinosaurs that had dominated during the Mesozoic. Some flightless birds grew larger than humans. These species are sometimes referred to as " terror birds," and were formidable predators. Mammals came to occupy almost every available ecological niche, niche (both marine and terrestrial animal, terrestrial), and some also grew very large, attaining sizes not seen in most of today's terrestrial mammals. During the Cenozoic, Mammal evolution#Expansion of ecological niches in the Mesozoic, mammals proliferated from a few small, simple, generalized forms into a diverse collection of Terrestrial animal, terrestrial, Marine mammal, marine, and bat, flying animals, giving this period its other name, the Age of Mammals. The Cenozoic is just as much the age of
savanna A savanna or savannah is a mixed woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the ' woods), a low-density forming open s with plenty of sunlight and li ...

savanna
s, the age of co-dependent flowering plants and insects, and the age of birds. Grass also played a very important role in this era, shaping the evolution of the birds and mammals that fed on it. One group that diversified significantly in the Cenozoic as well were the snakes. Evolving in the Cenozoic, the variety of snakes increased tremendously, resulting in many colubrids, following the evolution of their current primary prey source, the rodents. In the earlier part of the Cenozoic, the world was dominated by the Gastornithidae, gastornithid birds, terrestrial Crocodilia, crocodiles like ''Pristichampsus'', and a handful of primitive large mammal groups like uintatheres, mesonychids, and pantodonts. But as the forests began to recede and the climate began to cool, other mammals took over. The Cenozoic is full of mammals both strange and familiar, including chalicotheres, creodonts, whales, primates, entelodonts, saber-toothed cats, mastodons and
mammoth A mammoth is any species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organ ...

mammoth
s, three-toed horses, giant rhinoceros like ''Indricotherium'', the rhinoceros-like brontotheres, various bizarre groups of mammals from South America, such as the vaguely elephant-like pyrotheria, pyrotheres and the dog-like marsupial relatives called borhyaenidae, borhyaenids and the monotremes and marsupials of Australia.


See also

* Cretaceous–Paleogene boundary (K–T boundary) * Geologic time scale * Late Cenozoic Ice Age


References


Further reading

*


External links


Western Australian Museum – The Age of the Mammals


{{Authority control Cenozoic, Geological eras