Miocene
Overview
 
The Miocene is a geological epoch
Geologic time scale
The geologic time scale provides a system of chronologic measurement relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth...

 of the Neogene
Neogene
The Neogene is a geologic period and system in the International Commission on Stratigraphy Geologic Timescale starting 23.03 ± 0.05 million years ago and ending 2.588 million years ago...

 Period and extends from about (Ma). The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words (, “less”) and (, “new”) and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

. The Miocene follows the Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...

 Epoch and is followed by the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

 Epoch. The Miocene is the first epoch of the Neogene
Neogene
The Neogene is a geologic period and system in the International Commission on Stratigraphy Geologic Timescale starting 23.03 ± 0.05 million years ago and ending 2.588 million years ago...

 Period.

The earth went from the Oligocene Epoch through the Miocene and into the Pliocene as it cooled into a series of Ice Age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...

s.
Unanswered Questions
Encyclopedia
The Miocene is a geological epoch
Geologic time scale
The geologic time scale provides a system of chronologic measurement relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth...

 of the Neogene
Neogene
The Neogene is a geologic period and system in the International Commission on Stratigraphy Geologic Timescale starting 23.03 ± 0.05 million years ago and ending 2.588 million years ago...

 Period and extends from about (Ma). The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words (, “less”) and (, “new”) and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

. The Miocene follows the Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...

 Epoch and is followed by the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

 Epoch. The Miocene is the first epoch of the Neogene
Neogene
The Neogene is a geologic period and system in the International Commission on Stratigraphy Geologic Timescale starting 23.03 ± 0.05 million years ago and ending 2.588 million years ago...

 Period.

The earth went from the Oligocene Epoch through the Miocene and into the Pliocene as it cooled into a series of Ice Age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...

s. The Miocene boundaries are not marked by a single distinct global event but consist rather of regional boundaries between the warmer Oligocene and the cooler Pliocene.

The plants and animals of the Miocene were fairly modern. Mammals and birds were well-established. Whales, seals, and kelp spread. At the end of this epoch, the Himalayas started to rise.

Subdivisions

The Miocene faunal stage
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...

s from youngest to oldest are typically named according to the International Commission on Stratigraphy
International Commission on Stratigraphy
The International Commission on Stratigraphy , sometimes referred to by the unofficial "International Stratigraphic Commission" is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigraphy, geological, and geochronological matters on a global...

:
Messinian
Messinian
The Messinian is in the geologic timescale the last age or uppermost stage of the Miocene. It spans the time between 7.246 ± 0.005 Ma and 5.332 ± 0.005 Ma...

(7.246–5.332 Ma)
Tortonian
Tortonian
The Tortonian is in the geologic timescale an age or stage of the late Miocene that spans the time between 11.608 ± 0.005 Ma and 7.246 ± 0.005 Ma . It follows the Serravallian and is followed by the Messinian....

(11.608–7.246 Ma)
Serravallian
Serravallian
The Serravallian is in the geologic timescale an age or a stage in the middle Miocene epoch/series, that spans the time between 13.65 ± 0.05 Ma and 11.608 ± 0.005 Ma...

(13.65–11.608 Ma)
Langhian
Langhian
The Langhian is, in the ICS geologic timescale, an age or stage in the middle Miocene epoch/series. It spans the time between 15.97 ± 0.05 Ma and 13.65 ± 0.05 Ma . The Langhian was a continuing warming period defined by Lorenzo Pareto in 1864, it was originally established in the Langhe area north...

(15.97–13.65 Ma)
Burdigalian
Burdigalian
The Burdigalian is, in the geologic timescale, an age or stage in the early Miocene. It spans the time between 20.43 ± 0.05 Ma and 15.97 ± 0.05 Ma...

(20.43–15.97 Ma)
Aquitanian
Aquitanian age
The Aquitanian is, in the ICS' geologic timescale, the oldest age or lowest stage in the Miocene. It spans the time between 23.03 ± 0.05 Ma and 20.43 ± 0.05 Ma and is a dry, cooling period...

(23.03–20.43 Ma)


These subdivisions within the Miocene are defined by the relative abundance of different species of calcareous nanofossils (calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...

 platelets shed by brown single-celled algae) and foraminifera
Foraminifera
The Foraminifera , or forams for short, are a large group of amoeboid protists which are among the commonest plankton species. They have reticulating pseudopods, fine strands of cytoplasm that branch and merge to form a dynamic net...

 (single-celled protists with diagnostic shells). Two subdivisions each form the Early, Middle and Late Miocene.

Regionally, other systems are used. These ages often extend across the ICS epoch boundary into the Pliocene and Oligocene:

Australia

Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

n Miocene ages are very finely divided in the early Middle Miocene, while most of the rest of the Miocene had a rather constant fauna as far as is known:
Mitchellian (10.5–5 Ma); extends into the Early Pliocene
Bairnsdalian (15–10.5 Ma)
Balcombian (15.5–15 Ma)
Batesfordian (16.5–15.5 Ma)
Longfordian (27.5–16.5 Ma); includes much of the Late Oligocene

California

California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

n sites provide a sequence distinct from the main North American one:
Delmontian (7.5 –2.9 Ma); includes much of the Pliocene
Mohnian (13.5–7.5 Ma)
Luisian (15.5–13.5 Ma)
Relizian (16.5–15.5 Ma)
Saucesian (22–16.5 Ma)
Zemorrian (33.5–22 Ma); includes nearly all the Oligocene

Japan

Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

ese Miocene ages only start in the mid-Burdigalian; the ICS ages are used in much of the Early Miocene:
Yuian (9.5–3.6 Ma); includes the Early Pliocene
Fujian (11.1–9.5 Ma)
Kaburan (13.5–11.1 Ma)
Tozawan (15.97–13.5 Ma)
Haranoyan (18.2–15.97 Ma)

New Zealand

In New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, the following ages are recognized:
Kapitean (6–4.8 Ma); extends into the Early Pliocene
Tongaporutuan (10–6 Ma)
Waiauan (11.5–10 Ma)
Lillburnian (15–11.5 Ma)
Cliffdenian (16.5–15 Ma)
Altonian (17.5–16.5 Ma)
Awamoan (20–17.5 Ma)
Hutchinsonian (21–20 Ma)
Otaian (23.03–21 Ma)

North America

In most of North America, faunal stages are defined according to the land mammal fauna (North American Land Mammal Ages or NALMA
Nalma
Nalma is a village development committee in Lamjung District in the Gandaki Zone of northern-central Nepal. At the time of the 1991 Nepal census it had a population of 2082 people living in 409 individual households.-External links:*...

s):
Hemphillian
Hemphillian
The Hemphillian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 10,300,000 to 4,900,000 years BP, a period of . It is usually considered to overlap the Tortonian epoch of the Late...

(9–4.75 Ma); includes much of the Early Pliocene
Clarendonian
Clarendonian
The Clarendonian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 13,600,000 to 10,300,000 years BP, a period of . It is usually considered to overlap the Serravallian of the Middle...

(11.8–9 Ma)
Barstovian
Barstovian
The Barstovian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 16,300,000 to 13,600,000 years BP, a period of . It is usually considered to overlap the Langhian and Serravallian...

(15.5–11.8 Ma)
Hemingfordian (19–15.5 Ma)
Arikareean
Arikareean
The Arikareean North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 30,600,000 to 20,800,000 years BP, a period of . It is usually considered to overlap the Oligocene and Miocene epochs...

(30.5–19 Ma); includes much of the Oligocene

South America

In South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

, a system similar to the North American one is used; its periods are correspondingly called SALMAs (South American Land Mammal Ages):
Huayquerian
Huayquerian
The Huayquerian age is a period of geologic time within the Miocene epoch of the Neogene used more specifically with South American Land Mammal Ages. It follows the Mayoan and precedes the Montehermosan age....

(9–5.4 Ma); the Montehermosan
Montehermosan
The Montehermosan age is a period of geologic time within the Miocene epoch of the Neogene used more specifically with South American Land Mammal Ages. It follows the Huayquerian and precedes the Chapadmalalan age....

 barely extends into the Pliocene
Chasicoan
Chasicoan
The Chasicoan age is a period of geologic time within the Miocene epoch of the Neogene used more specifically with South American Land Mammal Ages. It follows the Mayoan and precedes the Huayquerian age....

(10–9 Ma)
Mayoian (12–10 Ma)
Laventan
Laventan
The Laventan age is a period of geologic time within the Miocene epoch of the Neogene used more specifically with South American Land Mammal Ages. It follows the Colloncuran and precedes the Mayoan age....

(13.8–12 Ma)
Colloncurian (15.5–12 Ma)
Friasian
Friasian
The Friasian age is a period of geologic time within the Miocene epoch of the Neogene used more specifically with South American Land Mammal Ages. It follows the Santacrucian and precedes the Colloncuran age....

(16.3–15.5 Ma)
Santacrucian
Santacrucian
The Santacrucian age is a period of geologic time within the Miocene epoch of the Neogene used more specifically with South American Land Mammal Ages. It follows the Colhuehuapian and precedes the Friasian age....

(17.5–16.3 Ma)
Colhuehuapian
Colhuehuapian
The Colhuehuapian age is a period of geologic time within the Miocene epoch of the Neogene used more specifically with South American Land Mammal Ages. It follows the Deseadan and precedes the Santacrucian age....

(21–17.5 Ma)
Deseadan
Deseadan
The Deseadan age is a period of geologic time within the Oligocene epoch of the Paleogene used more specifically with South American Land Mammal Ages. It follows the Tinguirirican and precedes the Colhuehuapian age....

(29–21 Ma); includes much of the Oligocene


Paleogeography

Continent
Continent
A continent is one of several very large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents—they are : Asia, Africa, North America, South America, Antarctica, Europe, and Australia.Plate tectonics is...

s continued to drift
Continental drift
Continental drift is the movement of the Earth's continents relative to each other. The hypothesis that continents 'drift' was first put forward by Abraham Ortelius in 1596 and was fully developed by Alfred Wegener in 1912...

 toward their present positions. Of the modern geologic features, only the land bridge between South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

 and North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 was absent, although South America was approaching the western subduction zone in the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

, causing both the rise of the Andes
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...

 and a southward extension of the Meso-American peninsula.

Mountain building took place in Western North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

, Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, and east Asia
East Asia
East Asia or Eastern Asia is a subregion of Asia that can be defined in either geographical or cultural terms...

. Both continental and marine Miocene deposits are common worldwide with marine outcrops common near modern shorelines. Well studied continental exposures occur in the American Great Plains
Great Plains
The Great Plains are a broad expanse of flat land, much of it covered in prairie, steppe and grassland, which lies west of the Mississippi River and east of the Rocky Mountains in the United States and Canada. This area covers parts of the U.S...

 and in Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

.

India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

 continued to collide with Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

, creating dramatic new mountain ranges. The Tethys
Tethys Ocean
The Tethys Ocean was an ocean that existed between the continents of Gondwana and Laurasia during the Mesozoic era before the opening of the Indian Ocean.-Modern theory:...

 Seaway continued to shrink and then disappeared as Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

 collided with Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...

 in the Turkish
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...

-Arabian region between 19 and 12 Ma. The subsequent uplift of mountains in the western Mediterranean region and a global fall in sea levels combined to cause a temporary drying up of the Mediterranean Sea (known as the Messinian salinity crisis
Messinian salinity crisis
The Messinian Salinity Crisis, also referred to as the Messinian Event, and in its latest stage as the Lago Mare event, was a geological event during which the Mediterranean Sea went into a cycle of partly or nearly complete desiccation throughout the latter part of the Messinian age of the Miocene...

) near the end of the Miocene.

The global trend was towards increasing aridity caused primarily by global cooling reducing the ability of the atmosphere to absorb moisture. Uplift of East Africa
East Africa
East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...

 in the Late Miocene was partly responsible for the shrinking of tropical rain forests in that region, and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 got drier as it entered a zone of low rainfall in the Late Miocene.

Flora

Grasslands underwent a major expansion; forests fell victim to a generally cooler and drier climate overall. Grasses also diversified greatly, co-evolving
Co-evolution
In biology, coevolution is "the change of a biological object triggered by the change of a related object." Coevolution can occur at many biological levels: it can be as microscopic as correlated mutations between amino acids in a protein, or as macroscopic as covarying traits between different...

 with large herbivores and grazers, including ruminant
Ruminant
A ruminant is a mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first compartment of the stomach, principally through bacterial actions, then regurgitating the semi-digested mass, now known as cud, and chewing it again...

s. Between 7 and 6 million years ago, there occurred a sudden expansion of grasses which were able to assimilate carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 more efficiently but were also richer in silica, causing a worldwide extinction of large herbivores. The expansion of grasslands and radiations
Evolutionary radiation
An evolutionary radiation is an increase in taxonomic diversity or morphological disparity, due to adaptive change or the opening of ecospace. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment,...

 among terrestrial herbivores such as horses can be linked to fluctuations in CO2.
Cycads between 11.5 and 5 m.y.a. began to rediversify after previous declines in variety due to climatic changes, and thus modern cycads are not a good model for a "living fossil".

Fauna

Both marine and continental fauna were fairly modern, although marine mammals were less numerous. Only in isolated South America and Australia did widely divergent fauna exist.
In the Early Miocene, several Oligocene groups were still diverse, including nimravids, entelodont
Entelodont
Entelodonts, sometimes nicknamed hell pigs or terminator pigs, is an extinct family of pig-like omnivores endemic to forests and plains of North America, Europe, and Asia from the middle Eocene to early Miocene epochs , existing for approximately .-Taxonomy:Entelodontidae was named by Richard...

s, and three-toed horses. Like in the previous Oligocene epoch, oreodont
Oreodont
Oreodons, sometimes called prehistoric "ruminating hogs," were a family of cud-chewing plant-eater with a short face and tusk-like canine teeth...

s were still diverse, only to disappear in the earliest Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

. During the later Miocene mammals were more modern, with recognizable dogs, raccoons, horse
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...

s, beaver
Beaver
The beaver is a primarily nocturnal, large, semi-aquatic rodent. Castor includes two extant species, North American Beaver and Eurasian Beaver . Beavers are known for building dams, canals, and lodges . They are the second-largest rodent in the world...

, deer
Deer
Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...

, camel
Camel
A camel is an even-toed ungulate within the genus Camelus, bearing distinctive fatty deposits known as humps on its back. There are two species of camels: the dromedary or Arabian camel has a single hump, and the bactrian has two humps. Dromedaries are native to the dry desert areas of West Asia,...

s, and whale
Whale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...

s, along with now extinct groups like borophagine dog
Borophaginae
The subfamily Borophaginae is an extinct group of canids called "bone crushing dogs" that were endemic to North America during the Oligocene to Pliocene and lived roughly 36—2.5 million years ago and existing for approximately .-Origin:...

s, gomphotheres, three-toed horses, and semi-aquatic and hornless rhinos like Teleoceras
Teleoceras
Teleoceras is an extinct genus of grazing rhinoceros that lived in North America during the Miocene epoch, which ended about 5.3 million years ago, all the way to the early Pliocene epoch....

and Aphelops
Aphelops
Aphelops is an extinct genus of rhinoceros endemic to North America during the Miocene through the Pliocene, living from 20.43—5.330 mya, existing for approximately .-Taxonomy:...

. Islands began to form between South and North America in the Late Miocene, allowing ground sloths like Thinobadistes
Thinobadistes
Thinobadistes is an extinct genus of actively mobile ground sloth of the family Mylodontidae, endemic to North America during the Miocene-Pleistocene epochs. It lived from 13.6—5.3 mya, existing for approximately ....

to island-hop
Rafting event
Oceanic dispersal is a type of biological dispersal that occurs when organisms transfer from one land mass to another by way of a sea crossing on large clumps of floating vegetation. Such matted clumps of vegetation are often seen floating down major rivers in the tropics and washing out to sea,...

 to North America.

Unequivocally recognizable dabbling ducks, plover
Plover
Plovers are a widely distributed group of wading birds belonging to the subfamily Charadriinae. There are about 40 species in the subfamily, most of them called "plover" or "dotterel". The closely related lapwing subfamily, Vanellinae, comprises another 20-odd species.Plovers are found throughout...

s, typical owl
Typical owl
True owl or Typical owl are one of the two generally accepted families of Owls, the other being the barn owls . The Sibley-Ahlquist taxonomy unites the Caprimulgiformes with the owl order; here, the typical owls are a subfamily Strigidae...

s, cockatoo
Cockatoo
A cockatoo is any of the 21 species belonging to the bird family Cacatuidae. Along with the Psittacidae and the Strigopidae , they make up the parrot order Psittaciformes . Placement of the cockatoos as a separate family is fairly undisputed, although many aspects of the other living lineages of...

s and crow
Crow
Crows form the genus Corvus in the family Corvidae. Ranging in size from the relatively small pigeon-size jackdaws to the Common Raven of the Holarctic region and Thick-billed Raven of the highlands of Ethiopia, the 40 or so members of this genus occur on all temperate continents and several...

s appear during the Miocene. By the epoch's end, all or almost all modern bird families
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 are believed to have been present; the few post-Miocene bird fossils which cannot be placed in the evolutionary tree with full confidence are simply too badly preserved instead of too equivocal in character. Marine birds reached their highest diversity ever in the course of this epoch.

Approximately 100 species of ape
Ape
Apes are Old World anthropoid mammals, more specifically a clade of tailless catarrhine primates, belonging to the biological superfamily Hominoidea. The apes are native to Africa and South-east Asia, although in relatively recent times humans have spread all over the world...

s lived during this time. They ranged over much of the Old World
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....

 and varied widely in size, diet, and anatomy. Due to scanty fossil evidence it is unclear which ape or apes contributed to the modern hominid clade, but molecular evidence indicates this ape lived from between 15 to 12 million years ago.

In the oceans, Brown algae, called kelp
Kelp
Kelps are large seaweeds belonging to the brown algae in the order Laminariales. There are about 30 different genera....

, proliferated, supporting new species of sea life, including otter
Otter
The Otters are twelve species of semi-aquatic mammals which feed on fish and shellfish, and also other invertebrates, amphibians, birds and small mammals....

s, fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 and various invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...

s.

Cetaceans attained their greatest diversity during the Miocene, with over 20 recognized genera in comparison to only six living genera. This diversification correlates with emergence of gigantic macro-predators such as megatoothed sharks and raptorial sperm whale
Sperm Whale
The sperm whale, Physeter macrocephalus, is a marine mammal species, order Cetacea, a toothed whale having the largest brain of any animal. The name comes from the milky-white waxy substance, spermaceti, found in the animal's head. The sperm whale is the only living member of genus Physeter...

s. Prominent examples are C. megalodon and L. melvillei. Other notable large sharks were C. chubutensis
Carcharocles chubutensis
Carcharocles chubutensis is a prehistoric megatoothed shark that lived during Oligocene, Miocene, and Pliocene epochs, approximately about 28 - 5 million years ago. This shark is considered to be a close relative of another prehistoric megatoothed shark, C. megalodon. However, as is the case with C...

, Isurus hastalis, and Hemipristis serra
Hemipristis serra
Hemipristis serra is an extinct species of weasel shark which existed during the Miocene period. It was described by Agassiz in 1843....

.

Crocodilians also showed signs of diversification during Miocene. The largest form among them was a gigantic caiman
Caiman
Caimans are alligatorid crocodylians within the subfamily Caimaninae. The group is one of two subfamilies of the family Alligatoridae, the other being alligators. Caimans inhabit Central and South America. They are relatively small crocodilians, with most species reaching lengths of only a few...

 Purussaurus
Purussaurus
Purussaurus is an extinct genus of giant caiman that lived in South America during the Miocene epoch, 8 million years ago. It is known from skull material found in the Brazilian, Colombian and Peruvian Amazonia, and northern Venezuela. The estimated skull length for one large individual of the type...

which inhabited South America. Another gigantic form was a false gharial
False gharial
The false gharial , also known as the Malayan gharial, false gavial, or Tomistoma is a freshwater crocodile of the Crocodylidae family with a very thin and elongated snout...

 Rhamphosuchus
Rhamphosuchus
Rhamphosuchus is an extinct relative of the modern false gharial. It inhabited what is now the Indian sub-continent in the Miocene...

, which inhabited modern age India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

. A strange form Mourasuchus
Mourasuchus
Mourasuchus is an extinct genus of giant crocodilian from the Miocene of South America. It was similar in length and weight to Rhamphosuchus...

also thrived alongside Purussaurus. This species developed a specialized filter-feeding mechanism, and it likely preyed upon small fauna despite of its gigantic size.

The pinniped
Pinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...

s, which appeared near the end of the Oligocene, became more aquatic. Prominent genus was Allodesmus
Allodesmus
Allodesmus is an extinct genus of pinniped from the Miocene and related to the genus Desmatophoca. It measured about long and weighed .- References :* After the Dinosaurs: The Age of Mammals by Donald R. Prothero...

. A ferocious walrus
Walrus
The walrus is a large flippered marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and sub-Arctic seas of the Northern Hemisphere. The walrus is the only living species in the Odobenidae family and Odobenus genus. It is subdivided into three subspecies: the Atlantic...

, Pelagiarctos
Pelagiarctos
Pelagiarctos was a genus of walrus that lived during the Mid Miocene, approx. 13-15 mya. Its remains have been found in the Sharktooth Hill Bonebed, in Kern county, California...

may have preyed upon other species of pinnipeds including Allodesmus.

Furthermore, South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

n waters witnessed the arrival of Megapiranha paranensis
Megapiranha
Megapiranha is a genus of extinct serrasalmid characin fish from the Late Miocene of Argentina described in 2009. Megapiranha reached lengths of up to 1 meter long, four times the size of the modern-day piranha...

, which were considerably larger then modern age piranhas
Piranhas
Piranhas is a historic city and municipality in the western of the State of Alagoas, in the Northeast Region of Brazil. Located on the bank of the São Francisco River, just at the border with the State of Sergipe, Piranhas was founded in 1891 and originally named Floriano Peixoto...

.

Oceans

There is evidence from oxygen isotopes at Deep Sea Drilling Program
Deep Sea Drilling Program
The Deep Sea Drilling Project was an ocean drilling project operated from 1968 to 1983. The program was considered to be successful as evidenced by the data and publications that have resulted from it and is now supported by Texas A&M University, although for the years of its operations these were...

 sites that ice began to build up in Antarctica about 36 Ma during the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...

. Further marked decreases in temperature during the Middle Miocene
Middle Miocene
The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene....

 at 15 Ma probably reflect increased ice growth in Antarctica. It can therefore be assumed that East Antarctica had some glaciers during the early to mid Miocene (23–15 Ma). Oceans cooled partly due the formation of the Antarctic Circumpolar Current
Antarctic Circumpolar Current
The Antarctic Circumpolar Current is an ocean current that flows from west to east around Antarctica. An alternative name for the ACC is the West Wind Drift. The ACC is the dominant circulation feature of the Southern Ocean and, at approximately 125 Sverdrups, the largest ocean current...

, and about 15 million years ago the ice cap in the southern hemisphere started to grow to its present form. The Greenland ice cap developed later, in the Middle Pliocene time, about 3 million years ago.

See also

  • Astaracian
    Astaracian
    The Astaracian age age is a period of geologic time , equivalent with the Middle Miocene and used more specifically with European Land Mammal Ages. It precedes the Vallesian age and follows the Orleanian age. The Astaracian overlaps the Langhian and Serravallian ages....

  • Turolian
    Turolian
    The Turolian age is a period of geologic time within the Miocene used more specifically with European Land Mammal Ages. It precedes the Ruscinian age and follows the Vallesian age. The Turolian overlaps the Tortonian and Messinian ages....

  • Vallesian
    Vallesian
    The Vallesian age is a period of geologic time within the Miocene used more specifically with European Land Mammal Ages. It precedes the Turolian age and follows the Astaracian age. The Turolian overlaps the Tortonian and Messinian ages....

  • Geologic Time Scale
    Geologic time scale
    The geologic time scale provides a system of chronologic measurement relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth...

  • List of fossil sites

:Category:Miocene animals
  • Lystromycter
    Lystromycter
    Lystromycter is an extinct genus of worm lizard from the Early Miocene of Africa.-Sources:* Fossils by David Ward...


Further reading

(1993): Biogeography. An ecological and evolutionary approach (5th ed.). Blackwell Scientific Publications, Cambridge. ISBN 0632029676 (2004): Overview of Global Boundary Stratotype Sections and Points (GSSP's). Retrieved 2006-04-30.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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