The Pliocene epoch (spelled Pleiocene in some older texts) is the period in the geologic timescale that extends from 5. The Holocene is a Geological epoch which began approximately 10000 years ago (about 8000 BC In the 8th millennium BC, Agriculture becomes widely practiced in the Fertile Crescent and Anatolia. In Paleoclimatology of the Holocene, the Boreal was the first of the Blytt-Sernander sequence of North European climatic phases that were originally The Atlantic in palaeoclimatology was the warmest and most moist Blytt-Sernander period Pollen zone and chronozone of Holocene north Europe. The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other 332 million to 1. 806 million years before present.

The Pliocene is the second epoch of the Neogene period in the Cenozoic era. The Neogene is a geologic period and system starting 2303 ± 0 The Cenozoic (also Caenozoic or Cainozoic) Era (ˌsiːnəˈzoʊɪk/ /ˌsɛn- (meaning "new life" ( Greek ( kainos) "new" The Pliocene follows the Miocene epoch and is followed by the Pleistocene epoch. The Miocene is a geological epoch of the Neogene period and extends from about 23 The Pleistocene ('plaɪstəsin is the epoch from 18 million to 10000 years BP covering the world's recent period

The Pliocene was named by Sir Charles Lyell. Sir Charles Lyell 1st Baronet, KT, FRS (14 November 1797 &ndash 22 February 1875 was a Scottish Lawyer, Geologist, and protagonist The name comes from the Greek words πλεῖον (pleion, "more") and καινός (kainos, "new") and means roughly "continuation of the recent", referring to the essentially modern marine mollusc faunas. Molluscs are animals belonging to the phylum Mollusca. There are around 250000 extant Species within the phylum with an estimated 70000

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. In Geology and related fields a stratum (plural strata) is a layer of rock or Soil with internally consistent characteristics that distinguishes The boundaries defining the onset of 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 intended to be set at the start of the Pleistocene glaciations but is now considered to be set too late. Many geologists find the broader divisions into Paleogene and Neogene more useful. The Paleogene (alternatively Palaeogene) is a geologic period and system that began 65

Astronomer Narciso Benítez of Johns Hopkins University and his team suggest that a supernova is a plausible but unproven candidate for the marine extinctions that characterize the Pliocene-Pleistocene boundary, by causing a significant breakdown of the ozone layer. A supernova (plural supernovae or supernovas) is a stellar Explosion. The photochemical mechanisms that give rise to the ozone layer were worked out by the British physicist Sidney Chapman in 1930

Subdivisions

The Pliocene faunal stages from youngest to oldest according to ICS classification are:

The first two stages make up the Late Pliocene, whereas the Zanclean is the only stage of the Early Pliocene. The Piacenzian may informally also be called "Middle Pliocene".

For most of North America, a different system (NALMA) is often used which overlaps epoch boundaries:

Other classification systems are used for California, Australia, Japan and New Zealand. California ( is a US state on the West Coast of the United States, along the Pacific Ocean. For a topic outline on this subject see List of basic Australia topics. For a topic outline on this subject see List of basic Japan topics. New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island

Climate

Climates became cooler and drier, and seasonal, similar to modern climates. Ice sheets grew on Antarctica during the Pliocene. An ice sheet is a mass of Glacier Ice that covers surrounding terrain and is greater than 50000 km² (20000 mile²) The continent was ice-bound, entirely covered with perennial glaciers, by the start of the Pliocene. The formation of an Arctic ice cap around 3 mya is signaled by an abrupt shift in oxygen isotope ratios and ice-rafted cobbles in the North Atlantic and North Pacific ocean beds (Van Andel 1994 p. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides Ice rafting is the transport of various material by Ice. Various objects deposited on ice may eventually become embedded in the ice The Pacific Ocean is the largest of the Earth 's Oceanic divisions 226). Mid-latitude glaciation was probably underway before the end of the epoch. "Glacial" and "Glaciation" redirect here For the geological periods see Glacial period. The global cooling that occurred during the Pliocene may have spurred on the disappearance of forests and the spread of grasslands and savannas. ^[1]

Paleogeography

Continents continued to drift toward their present positions, moving from positions possibly as far as 250 km from their present locations to positions only 70 km from their current locations. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere South America became linked to North America through the Isthmus of Panama during the Pliocene, bringing a nearly complete end to South America's distinctive marsupial faunas. South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a The Isthmus of Panama, also historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Marsupials are an Infraclass of Mammals characterized by a distinctive pouch (called the marsupium) in which females carry their young through 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's collision with Europe formed the Mediterranean Sea, cutting off the remnants of the Tethys Ocean. The Tethys Ocean was a Mesozoic era Ocean that existed between the continents of Gondwana and Laurasia before the opening of the Indian

Sea level changes exposed the land-bridge between Alaska and Asia. Alaska ( Аляска Alyaska) is a state in the United States of America, in the northwest of the North American continent

Pliocene marine rocks are well exposed in the Mediterranean, India, and China. India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National Elsewhere, they are exposed largely near shores.

Flora

The change to a cooler, dry, seasonal climate had considerable impacts on Pliocene vegetation, reducing tropical species world-wide. Deciduous forests proliferated, coniferous forests and tundra covered much of the north, and grasslands spread on all continents (except Antarctica). Botany Autumn leaf color. See --> In Botany and Horticulture, deciduous Plants, including In physical Geography, tundra is an area where the Tree growth is hindered by low temperatures and short growing seasons Grasslands (also called greenswards) are areas where the Vegetation is dominated by Grasses ( Poaceae) and other Herbaceous (non-woody Tropical forests were limited to a tight band around the equator, and in addition to dry savannahs, deserts appeared in Asia and Africa. A savanna or savannah is a Tropical or Subtropical Grassland or Woodland Ecosystem. A desert is a Landscape or region that receives very little precipitation.

Fauna

Oliva sayana, Florida (United States)

Archaeogastropod from the Pliocene of Cyprus. The lettered olive, Oliva sayana, is a Species of large Predatory sea Snail, a marine Gastropod Mollusc Cyprus (Κύπρος transliterated: Kýpros,; Kıbrıs officially the Republic of Cyprus (Κυπριακή Δημοκρατία Kypriakī́ Dīmokratía A serpulid worm is attached.

The coral Cladocora from the Pliocene of Cyprus. Cyprus (Κύπρος transliterated: Kýpros,; Kıbrıs officially the Republic of Cyprus (Κυπριακή Δημοκρατία Kypriakī́ Dīmokratía

Both marine and continental faunas were essentially modern, although continental faunas were a bit more primitive than today. The first recognizable hominins, the australopithecines, appeared in the Pliocene. Hominini is the tribe of Homininae that comprises humans ( Homo) Chimpanzees ( Pan) and their Extinct ancestors The term australopithecine refers to two very closely related genera within the Hominina subtribe of the Hominini tribe.

The land mass collisions meant great migration and mixing of previously isolated species, such as in the Great American Interchange. The Great American Interchange was an important paleozoogeographic event in which land and freshwater fauna migrated from North America via Central Herbivores got bigger, as did specialized predators. Herbivory is a form of Predation in which an Organism, known as a herbivore, consumes principally Autotrophs ref name=Campbell>Campbell

Mammals

In North America, rodents, large mastodonts and gomphotheres, and opossums continued successfully, while hoofed animals (ungulates) declined, with camel, deer and horse all seeing populations recede. Rodentia is an order of Mammals also known as rodents, characterised by two continuously-growing incisors in the upper and lower jaws which must Mastodons or Mastodonts (from Greek μαστός and οδούς, meaning " Nipple tooth" are members of the extinct The Gomphotheres are a diverse group of Extinct Elephant -like animals ( Proboscideans that were widespread in North America during the Didelphimorphia is the order of common opossums of the Western Hemisphere. Ungulates (meaning roughly "being Hoofed quot or "hoofed animal" are several groups of Mammals most of which use the tips of their toes usually Camels are Even-toed ungulates within the Genus Camelus. The Dromedary, one-humped or Arabian camel has a single hump and the A deer is a Ruminant Mammal belonging to the family Cervidae. The horse ( Equus caballus) is a hoofed ( Ungulate) Mammal, one of eight living species of the family Equidae. Rhinos, tapirs and chalicotheres went extinct. Rhinoceros (raɪˈnɒsərəs often colloquially abbreviated rhino, is a name used to group five extant species of Odd-toed ungulates in the family Tapirs (ˈteɪpɚ as in "taper" or /təˈpɪər/ as "ta-pier" are large browsing Mammals, roughly pig-like in shape with short Chalicotheres (from Greek chalix, gravel + therion, beast were a group of perissodactyl Mammals that evolved in the mid Eocene Carnivores including the weasel family diversified, and dogs and fast-running hunting bears did well. A carnivore (ˈkɑrnɪvɔər meaning 'meat eater' ( Latin carne meaning 'flesh' and vorare meaning 'to devour' is any animal with a diet consisting Weasels are Mammals in the genus Mustela of the Mustelidae family. The dog ( Canis lupus familiaris) is a domesticated Subspecies of the gray wolf, a Mammal of the Canidae family of the order Ground sloths, huge glyptodonts and armadillos came north with the formation of the Isthmus of Panama. The living sloths comprise six Species of medium-sized Mammals that live in Central and South America belonging to the families Glyptodon (Greek for "grooved or carved tooth" was a large armored Mammal, related to the Armadillo, that lived during the Pleistocene Armadillos are small Placental Mammals known for having a leathery armor shell

In Eurasia rodents did well, while primate distribution declined. For the superstate in George Orwell 's novel see Nations of Nineteen Eighty-Four. A primate is a member of the biological order Primates ( Latin: "prime first rank" the group that contains Lemurs the Aye-aye Elephants, gomphotheres and stegodonts were successful in Asia, and hyraxes migrated north from Africa. Elephants ( family: Elephantidae) are large land Mammals of the order Proboscidea. The Gomphotheres are a diverse group of Extinct Elephant -like animals ( Proboscideans that were widespread in North America during the Stegodon is a Genus of the Extinct Subfamily Stegodontinae of the order Proboscidea. A hyrax (from Greek 'shrewmouse' Afrikaans: klipdassie, from Dutch: klipdas 'rockbadger' is any of four Species of fairly Horse diversity declined, while tapirs and rhinos did fairly well. The horse ( Equus caballus) is a hoofed ( Ungulate) Mammal, one of eight living species of the family Equidae. Cows and antelopes were successful, and some camel species crossed into Asia from North America. Cattle, colloquially referred to as cows, are domesticated Ungulates a member of the Subfamily Bovinae of the family Antelope are Ruminant hoofed Mammals of the family Bovidae in the order of Even-toed ungulates. Hyaenas and early saber-toothed cats appeared, joining other predators including dogs, bears and weasels. The Hyaenidae is a Mammalian family of order Carnivora. The Hyaenidae family native to both African and Asian continents consists of four The terms saber-toothed cat, sabertooth, and saber-toothed tiger describe numerous species mainly in the families Felidae (subfamily Machairodontinae

Africa was dominated by hoofed animals, and primates continued their evolution, with australopithecines (some of the first hominids) appearing in the late Pliocene. Human evolution, or anthropogenesis, is the part of biological Evolution concerning the emergence of Homo sapiens as a distinct Species The term australopithecine refers to two very closely related genera within the Hominina subtribe of the Hominini tribe. Rodents were successful, and elephant populations increased. Cows and antelopes continued diversification and overtaking pigs in numbers of species. Pigs, also called hogs or' swine', are Ungulates which have been domesticated as sources of food leather and similar products since ancient times Early giraffes appeared, and camels migrated via Asia from North America. The giraffe ( Giraffa camelopardalis) is an African Even-toed ungulate Mammal, the tallest of all land-living Animal Species Horses and modern rhinos came onto the scene. Bears, dogs and weasels (originally from North America) joined cats, hyaenas and civets as the African predators, forcing hyaenas to adapt as specialized scavengers. Civets are small lithe-bodied mostly arboreal Mammals native to the tropics of Africa and Asia

South America was invaded by North American species for the first time since the Cretaceous, with North American rodents and primates mixing with southern forms. The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of Litopterns and the notoungulates, South American natives, did well. The Litopterna ("Simple Ankles quot is an order of Fossil hoofed Mammals ( Ungulates from the Tertiary period that displays toe The notoungulates are an extinct order of hoofed Mammals ( Ungulates that were native to South America. Small weasel-like carnivorous mustelids and coatis migrated from the north. Mustelidae or Mustelids (from Latin mustela, Weasel) commonly referred to as the weasel family, is a family of carnivorous Mammals The coati, genera Nasua and Nasuella, also known as the hog-nosed coon snookum bear and Brazilian Aardvark is a member of the Raccoon family ( Procyonidae Grazing glyptodonts, browsing giant ground sloths and smaller armadillos did well. Glyptodon (Greek for "grooved or carved tooth" was a large armored Mammal, related to the Armadillo, that lived during the Pleistocene

The marsupials remained the dominant Australian mammals, with herbivore forms including wombats and kangaroos, and the huge diprotodonts. A kangaroo is a Marsupial from the family Macropodidae (macropods meaning 'large foot' Diprotodontia (Greek meaning "two front teeth" is a large order of about 120 Marsupial mammals including the Kangaroos Carnivorous marsupials continued hunting in the Pliocene, including dasyurids, the dog-like thylacine and cat-like Thylacoleo. The order Dasyuromorphia (meaning "hairy tail" is made up of most Carnivorous Marsupials including Quolls Dunnarts the The Thylacine (ˈθaɪləsaɪn -iːn ( Thylacinus cynocephalus Latin wolf-headed pouched dog was the largest known carnivorous Marsupial of modern Thylacoleo ("Pouch Lion" is an Extinct Genus of carnivorous Marsupials that lived in Australia from the late Pliocene The first rodents arrived, while bats did well, as did ocean-going whales. Whales are marine mammals which are neither Dolphins (ie members of the families Delphinidae or Platanistoidae) nor Porpoises Orcas The modern platypus, a monotreme, appeared. The Platypus ( Ornithorhynchus anatinus) is a semi- aquatic Mammal endemic to eastern Australia, including Tasmania. Monotremes (from the Greek monos 'single' + trema 'hole' referring to the Cloaca) are Mammals that lay eggs ( Prototheria) instead

Birds

The predatory phorusrhacids were rare in this time; among the last was Titanis, a large phorusrhacid that rivaled mammals as top predator. Phorusrhacids ("Rag-Bearers" or terror birds, were a family of large Carnivorous Flightless birds that were the dominant Titanis ( Etymology: Titanis after the titans Ancient Greek gods that preceded the Twelve Olympians, in allusion to the Its distinct feature was its claws, which had re-evolved for grasping prey, such as Hipparion. Hipparion (Greek "pony" is an extinct genus of horse It resembled the modern Horse, but still had vestigal outer toes (in addition to its Other birds probably evolved at this time, some modern, some now extinct.

Reptiles

Alligators and crocodiles died out in Europe as the climate cooled. for differences between alligators and crocodiles please see Crocodilia An Alligator is a Crocodilian in the Genus A crocodile is any Species belonging to the family Crocodylidae (sometimes classified instead as the Subfamily Crocodylinae) Venomous snake genera continued to increase as more rodents and birds evolved. A venomous snake is a Snake that uses modified saliva venom, usually delivered through highly specialized teeth such as hollow fangs for the purpose of Prey

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. Sea ice is formed from Ocean water that freezes Because the Oceans consist of Saltwater, this occurs at about -1 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. The Cenozoic (also Caenozoic or Cainozoic) Era (ˌsiːnəˈzoʊɪk/ /ˌsɛn- (meaning "new life" ( Greek ( kainos) "new" This may have contributed to further cooling of the oceans worldwide.

The Pliocene seas were alive with sea cows, seals and sea lions. Manatees ( family Trichechidae, Genus Trichechus) are large fully aquatic Marine mammals sometimes known as sea Pinnipeds ("fin-feet" lit "winged feet" or fin-footed mammals are a widely distributed and diverse group of semi-aquatic marine Mammals comprising For other uses of the term "sea lion" see Sea lion (disambiguation.

Supernovae

In 2002, astronomers discovered 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 150 light-years of Earth and that one or more supernovae may have occurred in this group at that time. In Astronomy, stellar classification is a classification of Stars based initially on photospheric temperature and its associated Spectral characteristics The Scorpius-Centaurus Association (sometimes called Sco-Cen) is the nearest OB Association to the Sun. A stellar association is a very loose Star cluster, looser than both Open clusters and Globular clusters Stellar associations will normally contain from A supernova (plural supernovae or supernovas) is a stellar Explosion. Such a close explosion could have damaged the Earth's ozone layer and caused the extinction of some ocean life (consider that at its peak, a supernova of this size could have the same absolute magnitude as an entire galaxy of 200 billion stars). In Astronomy, absolute magnitude (also known as absolute visual magnitude) is the Apparent magnitude an object would have if it were at a standard (Comins, Kaufmann pp. 359)

See also

• List of fossil sites (with link directory)

References

• Comins, Niel F. This is a worldwide list of important and/or well-known localities where Fossils have been found ; William J. Kaufmann III (2005). Discovering the Universe, 7th edition, New York, NY: Susan Finnemore Brennan. 0-7167-7584-0.  
• Ogg, Jim; June, 2004, Overview of Global Boundary Stratotype Sections and Points (GSSP's) http://www.stratigraphy.org/gssp.htm Accessed April 30, 2006.
• Van Andel, Tjeerd H. , New Views on an Old Planet: a History of Global Change (2nd edition, 1994)

External links

• BBC Changing Worlds: Pliocene
• Palaeos Pliocene
• PBS Change: Deep Time: Pliocene
• UCMP Berkeley Pliocene Epoch Page
• Mid-Pliocene Global Warming: NASA/GISS Climate Modeling
• "Supernova dealt deaths on Earth? Stellar blasts may have killed ancient marine life" Science News Online 2 February 2002
• Possible Pliocene supernova