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The Pliocene ( ; also Pleiocene) is the
epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided ...
in the
geologic time scale The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochr ...
that extends from 5.333 million to 2.58See the 2014 version of the ICS geologic time scale
million years ago. It is the second and most recent epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the
Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
Epoch and is followed by 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 was fina ...
Epoch. Prior to the 2009 revision of the geologic time scale, which placed the four most recent major glaciations entirely within the Pleistocene, the Pliocene also included the Gelasian Stage, which lasted from 2.588 to 1.806 million years ago, and is now included in the Pleistocene. As with other older geologic periods, the geological strata that define the start and end are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The boundaries defining the Pliocene are not set at an easily identified worldwide event but rather at regional boundaries between the warmer Miocene and the relatively cooler Pliocene. The upper boundary was set at the start of the Pleistocene glaciations.


Etymology

Charles Lyell (later Sir Charles) gave the Pliocene its name in ''Principles of Geology'' (volume 3, 1833). The word ''pliocene'' comes from the Greek words (, "more") and (, "new" or "recent") and means roughly "continuation of the recent", referring to the essentially modern marine mollusc fauna.


Subdivisions

In the official timescale of the ICS, the Pliocene is subdivided into two stages. From youngest to oldest they are: * Piacenzian (3.600–2.58 Ma) *
Zanclean The Zanclean is the lowest stage or earliest age on the geologic time scale of the Pliocene. It spans the time between 5.332 ± 0.005 Ma (million years ago) and 3.6 ± 0.005 Ma. It is preceded by the Messinian Age of the Miocene Epoch, a ...
(5.333–3.600 Ma) The Piacenzian is sometimes referred to as the Late Pliocene, whereas the Zanclean is referred to as the Early Pliocene. In the system of * North American Land Mammal Ages (NALMA) include Hemphillian (9–4.75 Ma), and
Blancan The Blancan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 4,750,000 to 1,806,000 years BP, a period of .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 was fina ...
. * South American Land Mammal Ages (SALMA) include Montehermosan (6.8–4.0 Ma),
Chapadmalalan The Chapadmalalan age is a period of geologic time (4.0–3.0 Ma) within the Pliocene epoch of the Neogene used more specifically with South American Land Mammal Ages. It follows the Montehermosan and precedes the Uquian age. Fossil content Fo ...
(4.0–3.0 Ma) and Uquian (3.0–1.2 Ma). In the Paratethys area (central
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
and parts of western Asia) the Pliocene contains the Dacian (roughly equal to the Zanclean) and Romanian (roughly equal to the Piacenzian and Gelasian together) stages. As usual in stratigraphy, there are many other regional and local subdivisions in use. In Britain, the Pliocene is divided into the following stages (old to young): Gedgravian, Waltonian, Pre-Ludhamian, Ludhamian, Thurnian, Bramertonian or Antian,
Pre-Pastonian The Pre-Pastonian Stage or Baventian Stage (from Easton Bavents in Suffolk), is the name for an early Pleistocene stage used in the British Isles. It precedes the Pastonian Stage and follows the Bramertonian Stage. This stage ended 1.806 Ma (mil ...
or Baventian, Pastonian and Beestonian. In the
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
the Pliocene is divided into these stages (old to young): Brunssumian C, Reuverian A, Reuverian B, Reuverian C,
Praetiglian The Tiglian, also referred to as the Tegelen, is a temperate complex stage in the glacial history of Northern Europe. It is preceded by the Praetiglian (stage). The stage was introduced by Zagwijn in 1957 based on geological formations in Tegelen i ...
, Tiglian A, Tiglian B, Tiglian C1-4b, Tiglian C4c, Tiglian C5, Tiglian C6 and Eburonian. The exact correlations between these local stages and 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 ...
(ICS) stages is still a matter of detail.


Climate

The beginning of the Pliocene was marked by an increase in global temperatures relative to the cooler Messinian related to the 1.2 million year obliquity amplitude modulation cycle. The global average temperature in the mid-Pliocene (3.3–3 mya) was 2–3 °C higher than today, carbon dioxide levels were the same as today, and global sea level was 25 m higher. The northern hemisphere ice sheet was ephemeral before the onset of extensive
glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate bet ...
over
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...
that occurred in the late Pliocene around 3 Ma. The formation of an Arctic ice cap is signaled by an abrupt shift in
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers ( mass num ...
ratios and ice-rafted cobbles in the North Atlantic and North Pacific Ocean beds.Van Andel (1994), p. 226. Mid-latitude glaciation was probably underway before the end of the epoch. The global cooling that occurred during the Pliocene may have spurred on the disappearance of forests and the spread of grasslands and savannas.


Paleogeography

Continents continued to
drift Drift or Drifts may refer to: Geography * Drift or ford (crossing) of a river * Drift, Kentucky, unincorporated community in the United States * In Cornwall, England: ** Drift, Cornwall, village ** Drift Reservoir, associated with the village ...
, moving from positions possibly as far as 250 km from their present locations to positions only 70 km from their current locations.
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...
became linked to North America through the Isthmus of Panama during the Pliocene, making possible the Great American Interchange and bringing a nearly complete end to South America's distinctive native ungulate fauna, though other South American lineages like its predatory mammals were already extinct by this point and others like xenarthrans continued to do well afterwards. The formation of the Isthmus had major consequences on global temperatures, since warm equatorial ocean currents were cut off and an Atlantic cooling cycle began, with cold Arctic and Antarctic waters dropping temperatures in the now-isolated Atlantic Ocean.
Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
's collision with
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
formed the
Mediterranean Sea 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 and Southern Europe and Anatolia, on the south by North Africa, and on ...
, cutting off the remnants of the Tethys Ocean. The border between the Miocene and the Pliocene is also the time of the Messinian salinity crisis. The land bridge between
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...
and Siberia ( Beringia) was first flooded near the start of the Pliocene, allowing marine organisms to spread between the Arctic and Pacific Oceans. The bridge would continue to be periodically flooded and restored thereafter. Pliocene marine formations are exposed in northeast
Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = '' Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , ...
, southern
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
,
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...
, and
Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
. During the Pliocene parts of southern Norway and southern Sweden that had been near sea level rose. In Norway this rise elevated the Hardangervidda plateau to 1200 m in the Early Pliocene. In Southern Sweden similar movements elevated the
South Swedish highlands 300px, Aerial view of farms and forest in Ydre Municipality. 250px, The forested landscape of the South Swedish highlands, seen from Eksjö_Municipality.html"_;"title="Skuruhatt_in_Eksjö_Municipality">Skuruhatt_in_Eksjö_Municipality. The_Sout ...
leading to a deflection of the ancient Eridanos river from its original path across south-central Sweden into a course south of Sweden.


Environment and evolution of human ancestors

The Pliocene is bookended by two significant events in the evolution of human ancestors. The first is the appearance of the
hominin The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos) and in standard usage excludes the genus ''Gorilla'' (gorillas). The ...
'' Australopithecus anamensis'' in the early Pliocene, around 4.2 million years ago. The second is the appearance of ''
Homo ''Homo'' () is the genus that emerged in the (otherwise extinct) genus '' Australopithecus'' that encompasses the extant species ''Homo sapiens'' ( modern humans), plus several extinct species classified as either ancestral to or closely rela ...
'', the genus that includes modern humans and their closest extinct relatives, near the end of the Pliocene at 2.6 million years ago. Key traits that evolved among hominins during the Pliocene include terrestrial bipedality and, by the end of the Pliocene, encephalized brains (brains with a large neocortex relative to body mass and stone tool manufacture. Improvements in dating methods and in the use of climate proxies have provided scientists with the means to test hypotheses of the evolution of human ancestors. Early hypotheses of the evolution of human traits emphasized the selective pressures produced by particular habitats. For example, many scientists have long favored the savannah hypothesis. This proposes that the evolution of terrestrial bipedality and other traits was an adaptive response to Pliocene climate change that transformed forests into more open savannah. This was championed by
Grafton Elliot Smith Sir Grafton Elliot Smith (15 August 1871 – 1 January 1937) was an Australian- British anatomist, Egyptologist and a proponent of the hyperdiffusionist view of prehistory. He believed in the idea that cultural innovations occur only once a ...
in his 1924 book, ''The Evolution of Man'', as "the unknown world beyond the trees", and was further elaborated by Raymond Dart as the
killer ape theory The killer ape theory or killer ape hypothesis is the theory that war and interpersonal aggression was the driving force behind human evolution. It was originated by Raymond Dart in the 1950s; it was developed further in '' African Genesis'' by Ro ...
. Other scientists, such as
Sherwood L. Washburn Sherwood Larned Washburn ( – ), nicknamed "Sherry", was an American physical anthropologist, and "a legend in the field." He was pioneer in the field of primatology, opening it to the study of primates in their natural habitats. His research ...
, emphasized an intrinsic model of hominin evolution. According to this model, early evolutionary developments triggered later developments. The model placed little emphasis on the surrounding environment. Anthropologists tended to focus on intrinsic models while geologists and vertebrate paleontologists tended to put greater emphasis on habitats. Alternatives to the savanna hypothesis include the woodland/forest hypothesis, which emphasizes the evolution of hominins in closed habitats, or hypotheses emphasizing the influence of colder habitats at higher latitudes or the influence of seasonal variation. More recent research has emphasized the variability selection hypothesis, which proposes that variability in climate fostered development of hominin traits. Improved climate proxies show that the Pliocene climate of east Africa was highly variable, suggesting that adaptability to varying conditions was more important in driving hominin evolution than the steady pressure of a particular habitat.


Flora

The change to a cooler, drier, more seasonal climate had considerable impacts on Pliocene vegetation, reducing tropical species worldwide.
Deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...
forests proliferated, coniferous forests and tundra covered much of the north, and grasslands spread on all continents (except Antarctica). Tropical forests were limited to a tight band around the equator, and in addition to dry savannahs, deserts appeared in Asia and Africa.


Fauna

Both marine and continental faunas were essentially modern, although continental faunas were a bit more primitive than today. The land mass collisions meant great migration and mixing of previously isolated species, such as in the Great American Interchange. Herbivores got bigger, as did specialized predators. Image:Oliva sayana.jpg, The gastropod ''
Oliva sayana The lettered olive, ''Oliva sayana'', is a species of large predatory sea snail, a marine gastropod mollusc in the family Olividae, the olive shells, olive snails, or olives. MolluscaBase eds. (2021). MolluscaBase. Oliva sayana Ravenel, 1834. A ...
'', from the Pliocene of
Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...
Image:Cladocora.jpg, The
coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and se ...
'' Cladocora'' from the Pliocene of
Cyprus Cyprus ; tr, Kıbrıs (), officially the Republic of Cyprus,, , lit: Republic of Cyprus is an island country located south of the Anatolian Peninsula in the eastern Mediterranean Sea. Its continental position is disputed; while it is ...
Image:CyprusPlioceneGastropod.JPG, A gastropod and attached serpulid wormtube from the Pliocene of Cyprus Image:Turritellatricarinata.jpg, The gastropod '' Turritella carinata'' from the Pliocene of Cyprus Image:SpondylusPliocene.jpg, The thorny
oyster Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not ...
''
Spondylus ''Spondylus'' is a genus of bivalve molluscs, the only genus in the family Spondylidae.MolluscaBase (2019). MolluscaBase. Spondylus Linnaeus, 1758. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=t ...
'' right and left valve interiors from the Pliocene of Cyprus Image:Diodoraitalica.jpg, The limpet ''Diodora italica'' from the Pliocene of Cyprus Image:DentaliumPliocene.jpg, The scaphopod '' Dentalium'' from the Pliocene of Cyprus File:Aporrhais from Pliocene.jpg, The gastropod ''
Aporrhais ''Aporrhais'' is a genus of medium-sized sea snails, marine gastropod mollusks in the family Aporrhaidae and the superfamily Stromboidea.
'' from the Pliocene of Cyprus Image:AnadaraPliocene.jpg, The arcid bivalve '' Anadara'' from the Pliocene of Cyprus Image:Amusium cristatum Cyprus.jpg, The pectenid bivalve ''Ammusium cristatum'' from the Pliocene of Cyprus Image:Petaloconchus Cyprus Pliocene.JPG, Vermetid gastropod ''
Petaloconchus intortus ''Petaloconchus intortus'' is an extinct species of sea snail, a marine gastropod mollusk in the family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other ...
'' attached to a branch of the
coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and se ...
''Cladocora'' from the Pliocene of Cyprus Image:Chesapecten barnacles Pliocene VA.jpg, ''
Chesapecten ''Chesapecten'' is an extinct genus of scallop known from marine strata from the early Miocene to the early Pleistocene of the Eastern United States. It flourished in the shallow seas along the Mid-Atlantic during this period. Other scallops ...
'',
barnacles A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosiv ...
and sponge borings ('' Entobia'') from the Pliocene of York River, Virginia


Mammals

In North America, rodents, large
mastodon A mastodon ( 'breast' + 'tooth') is any proboscidean belonging to the extinct genus ''Mammut'' (family Mammutidae). Mastodons inhabited North and Central America during the late Miocene or late Pliocene up to their extinction at the end of the ...
s and gomphotheres, and opossums continued successfully, while hoofed animals ( ungulates) declined, with camel,
deer Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the re ...
and
horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...
all seeing populations recede. Three-toed horses ('' Nannippus''), oreodonts, protoceratids, and
chalicothere Chalicotheres (from Greek '' chalix'', "gravel" and '' therion'', "beast") are an extinct clade of herbivorous, odd-toed ungulate (perissodactyl) mammals that lived in North America, Eurasia, and Africa from the Middle Eocene until the Early Ple ...
s became extinct. Borophagine dogs and ''
Agriotherium ''Agriotherium'' is an extinct genus of bears whose fossils are found in Miocene through Pleistocene-aged strata of North America, Europe, Africa, and Asia. This long-lived genus persisted from at least ~11.6–2.5 Mya. Materials from the late- ...
'' became extinct, but other carnivores including the
weasel Weasels are mammals of the genus ''Mustela'' of the family Mustelidae. The genus ''Mustela'' includes the least weasels, polecats, stoats, ferrets and European mink. Members of this genus are small, active predators, with long and slend ...
family diversified, and dogs and short-faced bears did well. Ground sloths, huge glyptodonts, and armadillos came north with the formation of the Isthmus of Panama. In
Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelag ...
rodents did well, while
primate Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians ( monkeys and apes, the latter includin ...
distribution declined.
Elephant Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantida ...
s, gomphotheres and stegodonts were successful in Asia (the largest land mammals of the Pliocene were such proboscideans as ''
Deinotherium ''Deinotherium'' was a large elephant-like proboscidean that appeared in the Middle Miocene and survived until the Early Pleistocene. Although superficially resembling modern elephants, they had notably more flexible necks, limbs adapted to a mo ...
'', '' Anancus'' and '' Mammut borsoni''), and hyraxes migrated north from Africa.
Horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...
diversity declined, while tapirs and rhinos did fairly well. Bovines and antelopes were successful; some camel species crossed into Asia from North America. Hyenas and early
saber-toothed cat Machairodontinae is an extinct subfamily of carnivoran mammals of the family Felidae (true cats). They were found in Asia, Africa, North America, South America, and Europe from the Miocene to the Pleistocene, living from about 16 million ...
s appeared, joining other predators including dogs, bears and weasels. Africa was dominated by hoofed animals, and primates continued their evolution, with
australopithecine Australopithecina or Hominina is a subtribe in the tribe Hominini. The members of the subtribe are generally ''Australopithecus'' ( cladistically including the genera ''Homo'', '' Paranthropus'', and ''Kenyanthropus''), and it typically inclu ...
s (some of the first
hominin The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos) and in standard usage excludes the genus ''Gorilla'' (gorillas). The ...
s) and baboon-like monkeys such as the ''
Dinopithecus ''Dinopithecus'' ("terrible ape") is an extinct genus of very large primate closely related to the baboon that lived during the Pliocene to the Pleistocene epoch of South Africa and Ethiopia. It was named by British paleontologist Robert Broom i ...
'' appearing in the late Pliocene. Rodents were successful, and elephant populations increased. Cows and antelopes continued diversification and overtook pigs in numbers of species. Early giraffes appeared. Horses and modern rhinos came onto the scene. Bears, dogs and weasels (originally from North America) joined cats, hyenas and civets as the African predators, forcing hyenas to adapt as specialized scavengers. Most mustelids in Africa declined as a result of increased competition from the new predators, although '' Enhydriodon omoensis'' remained an unusually successful terrestrial predator. South America was invaded by North American species for the first time since the
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
, with North American rodents and primates mixing with southern forms. Litopterns and the notoungulates, South American natives, were mostly wiped out, except for the macrauchenids and
toxodonts Toxodontia. Retrieved April 2013. is a suborder of the meridiungulate order Notoungulata. Most of the members of the five included families, including the largest notoungulates, share several dental, auditory and tarsal specializations. The gr ...
, which managed to survive. Small weasel-like carnivorous
mustelid The Mustelidae (; from Latin ''mustela'', weasel) are a family of carnivorous mammals, including weasels, badgers, otters, ferrets, martens, minks and wolverines, among others. Mustelids () are a diverse group and form the largest family in t ...
s,
coati Coatis, also known as coatimundis (), are members of the family Procyonidae in the genera ''Nasua'' and ''Nasuella''. They are diurnal mammals native to South America, Central America, Mexico, and the southwestern United States. The name ...
s and short-faced bears migrated from the north. Grazing glyptodonts, browsing
giant ground sloth ''Megatherium'' ( ; from Greek () 'great' + () 'beast') is an extinct genus of ground sloths endemic to South America that lived from the Early Pliocene through the end of the Pleistocene. It is best known for the elephant-sized type species ...
s and smaller caviomorph rodents,
pampathere Pampatheriidae (" Pampas beasts") is an extinct family of large plantigrade armored armadillos related to extant armadillos in the order Cingulata. However, pampatheriids have existed as a separate lineage since at least the middle Eocene Muster ...
s, and armadillos did the opposite, migrating to the north and thriving there. The marsupials remained the dominant Australian mammals, with herbivore forms including
wombat Wombats are short-legged, muscular quadrupedal marsupials that are native to Australia. They are about in length with small, stubby tails and weigh between . All three of the extant species are members of the family Vombatidae. They are ad ...
s and
kangaroo Kangaroos are four marsupials from the family Macropodidae (macropods, meaning "large foot"). In common use the term is used to describe the largest species from this family, the red kangaroo, as well as the antilopine kangaroo, eastern ...
s, and the huge ''
Diprotodon ''Diprotodon'' ( Ancient Greek: "two protruding front teeth") is an extinct genus of marsupial from the Pleistocene of Australia, containing one species, ''D. optatum''. The earliest finds date to 1.77 million to 780,000 years ago, but most s ...
''. Carnivorous marsupials continued hunting in the Pliocene, including dasyurids, the dog-like thylacine and cat-like '' Thylacoleo''. The first rodents arrived in Australia. The modern
platypus The platypus (''Ornithorhynchus anatinus''), sometimes referred to as the duck-billed platypus, is a semiaquatic, egg-laying mammal endemic to eastern Australia, including Tasmania. The platypus is the sole living representative or mono ...
, a monotreme, appeared.


Birds

The predatory South American phorusrhacids were rare in this time; among the last was '' Titanis'', a large phorusrhacid that migrated to North America and rivaled mammals as top predator. Other birds probably evolved at this time, some modern (such as the genera '' Cygnus'', '' Bubo'', ''
Struthio Ostriches are large flightless birds of the genus ''Struthio'' in the order Struthioniformes, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the emus, rheas, and kiwis. There are ...
'' and '' Corvus''), some now extinct.


Reptiles and amphibians

Alligator An alligator is a large reptile in the Crocodilia order in the genus ''Alligator'' of the family Alligatoridae. The two extant species are the American alligator (''A. mississippiensis'') and the Chinese alligator (''A. sinensis''). Additional ...
s and crocodiles died out in Europe as the climate cooled. Venomous snake genera continued to increase as more rodents and birds evolved. Rattlesnakes first appeared in the Pliocene. The modern species '' Alligator mississippiensis'', having evolved in the Miocene, continued into the Pliocene, except with a more northern range; specimens have been found in very late Miocene deposits of
Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. Tennessee is the List of U.S. states and territories by area, 36th-largest by ...
. Giant tortoises still thrived in North America, with genera like '' Hesperotestudo''. Madtsoid
snake Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more ...
s were still present in Australia. The amphibian order Allocaudata became extinct.


Oceans

Oceans continued to be relatively warm during the Pliocene, though they continued cooling. The Arctic ice cap formed, drying the climate and increasing cool shallow currents in the North Atlantic. Deep cold currents flowed from the Antarctic. The formation of the Isthmus of Panama about 3.5 million years ago cut off the final remnant of what was once essentially a circum-equatorial current that had existed since the Cretaceous and the early Cenozoic. This may have contributed to further cooling of the oceans worldwide. The Pliocene seas were alive with sea cows, seals, sea lions and
shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachi ...
s.


Supernovae

In 2002, Narciso Benítez ''et al.'' calculated that roughly 2 million years ago, around the end of the Pliocene Epoch, a group of bright O and B stars called the Scorpius–Centaurus OB association passed within 130 light-years of Earth and that one or more
supernova A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or whe ...
explosions gave rise to a feature known as the Local Bubble. Such a close explosion could have damaged the Earth's ozone layer and caused the extinction of some ocean life (at its peak, a supernova of this size could have the same
absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it ...
as an entire galaxy of 200 billion stars).Comins & Kaufmann (2005), p. 359. Radioactive iron-60 isotopes that have been found in ancient seabed deposits further back this finding, as there are no natural sources for this radioactive isotope on Earth, but they can be produced in supernovae. Furthermore, iron-60 residues point to a huge spike 2.6 million years ago, but an excess scattered over 10 million years can also be found, suggesting that there may have been multiple, relatively close supernovae. In 2019, researchers found more of these interstellar iron-60 isotopes in Antarctica, which have been associated with the
Local Interstellar Cloud The Local Interstellar Cloud (LIC), also known as the Local Fluff, is an interstellar cloud roughly across, through which the Solar System is moving. This feature overlaps a region around the Sun referred to as the solar neighborhood. It is un ...
.


See also

* List of fossil sites ''(with link directory)''


Notes


References


Further reading

* * ; 2004: ''A Geologic Time Scale 2004'',
Cambridge University , mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Schola ...
Press. * *


External links


Mid-Pliocene Global Warming: NASA/GISS Climate Modeling







"Supernova dealt deaths on Earth? Stellar blasts may have killed ancient marine life" ''Science News Online''
retrieved February 2, 2002


Pliocene Microfossils: 100+ images of Pliocene Foraminifera

Human Timeline (Interactive)
Smithsonian,
National Museum of Natural History The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with 7. ...
(August 2016). {{Authority control Geological epochs Neogene geochronology