The Miocene Epoch is a period of time that extends from about 23. The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other 03 to 5. 33 million years before the present. As with other older geologic periods, the rock beds that define the start and end are well identified but the exact dates of the start and end of the period are uncertain. The Miocene 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 Its name comes from the Greek words μείων (meioon, less) and καινός (kainos, new) and means "less recent" because it has 18% (fewer than the Pliocene) of modern sea invertebrates. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly The Pliocene epoch (spelled Pleiocene in some older texts is the period in the Geologic timescale that extends An invertebrate is an Animal lacking a Vertebral column. The group includes 98% of all animal Species — all animals except those in the Chordate The Miocene follows the Oligocene Epoch and is followed by the Pliocene Epoch. The Oligocene is a geologic epoch of the Paleogene period and extends from about 33 The Pliocene epoch (spelled Pleiocene in some older texts is the period in the Geologic timescale that extends The Miocene is the first epoch of the Neogene Period. The Neogene is a geologic period and system starting 2303 ± 0
As the earth cooled, it went from the Oligocene epoch through the Miocene and into the Pliocene. The Miocene boundaries are not set at an easily identified worldwide event but rather at 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.
Contents |
Subdivisions
The Miocene faunal stages from youngest to oldest are typically named according to the International Commission on Stratigraphy:
| Messinian | (7. The International Commission on Stratigraphy (ICS, sometimes referred to by the unofficial " International Stratigraphic Commission " is a daughter or major Subcommittee Messinian is the last Age of the Miocene epoch. It spans the time between 7 246 – 5. 332 mya) |
| Tortonian | (11. In Astronomy, Geology, and Paleontology, mya or " mya " is an abbreviation for "million years ago". Tortonian is a Age of the late Miocene epoch that spans the time between 11 608 – 7. 246 mya) |
| Serravallian | (13. Serravallian is a Age of the middle Miocene epoch that spans the time between 13 65 – 11. 608 mya) |
| Langhian | (15. Langhian is the older ICS Age of the Middle Miocene epoch. It spans the time between 15 97 – 13. 65 mya) |
| Burdigalian | (20. Burdigalian is a Age of the early Miocene Epoch. It spans the time between 20 43 – 15. 97 mya) |
| Aquitanian | (23. Aquitanian is the first Age of the Miocene Epoch. It spans the time between 23 03 – 20. 43 mya) |
These subdivisions within the Miocene are defined by the relative abundance of different species of calcareous nanofossils (calcite platelets shed by brown single-celled algae) and foraminifera (single-celled protists with diagnostic shells). Calcite is a carbonate mineral and the most stable polymorph of Calcium carbonate ( Ca[[carbon C]] O 3 The Foraminifera, ("Hole Bearers" or forams for short are a large group of Amoeboid Protists with reticulating Pseudopods fine Two subdivisions each form the Early, Middle and Late Miocene.
In most of North America, faunal stages are defined according to the land mammal fauna (North American Land Mammal Ages or NALMAs). They overlap the borders of the Miocene and Oligocene/Pliocene:
| Hemphillian | (9 – 4. 75 mya); includes much of the Early Pliocene |
| Clarendonian | (11. 8 – 9 mya) |
| Barstovian | (15. 5 – 11. 8 mya) |
| Hemingfordian | (19 – 15. 5 mya) |
| Arikareean | (30. 5 – 19 mya); includes much of the Oligocene |
Californian sites, which are derived from the former Farallon Plate, provide another sequence which also overlaps with the epoch boundaries:
| Delmontian | (7. California ( is a US state on the West Coast of the United States, along the Pacific Ocean. The Farallon Plate was an ancient Oceanic plate, which began Subducting under the west coast of the North American Plate &mdash then located in modern 5 – 2. 9 mya); includes much of the Pliocene |
| Mohnian | (13. 5 – 7. 5 mya) |
| Luisian | (15. 5 – 13. 5 mya) |
| Relizian | (16. 5 – 15. 5 mya) |
| Saucesian | (22 – 16. 5 mya) |
| Zemorrian | (33. 5 – 22 mya); includes nearly all the Oligocene |
Yet other systems are used to describe the Miocene stratigraphy of Japan, Australia and New Zealand. For a topic outline on this subject see List of basic Japan topics. For a topic outline on this subject see List of basic Australia topics. New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island
Paleogeography
Continents continued to drift toward their present positions. A continent is one of several large Landmasses on Earth. They are generally identified by Convention rather than any strict criteria with seven regions Continental drift is the movement of the Earth 's Continents relative to each other Of the modern geologic features, only the land bridge between South America and North America was absent, although South America was approaching the western subduction zone in the Pacific Ocean, causing both the rise of the Andes and a southward extension of the Meso-American peninsula. South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a In Geology, a subduction zone is an area on Earth where two tectonic plates meet and move towards one another with one sliding underneath the other The Pacific Ocean is the largest of the Earth 's Oceanic divisions The Andes form the world's longest exposed Mountain range. They lie as a continuous chain of highland along the western coast of South America. Mesoamerica or Meso-America (Mesoamérica is a Region extending approximately from central Mexico to Honduras and Nicaragua, defined
Mountain building took place in Western North America and Europe. 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 and in Argentina. The Great Plains are the broad expanse of Prairie and Steppe which lie east of the Rocky Mountains in the United States and Canada For a topic outline on this subject see List of basic Argentina topics.
India continued to collide with Asia, creating more mountain ranges. India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country The Tethys Seaway continued to shrink and then disappeared as Africa collided with Eurasia in the Turkish-Arabian region between 19 and 12 mya. The Tethys Ocean was a Mesozoic era Ocean that existed between the continents of Gondwana and Laurasia before the opening of the Indian For the superstate in George Orwell 's novel see Nations of Nineteen Eighty-Four. Turkey (Türkiye known officially as the Republic of Turkey ( is a Eurasian Country that stretches The Arabian Peninsula (in Arabic: شبه الجزيرة العربية šibh al-jazīra al-ʻarabīya or جزيرة العرب jazīrat al-ʻarab) 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) near the end of the Miocene. The Messinian Salinity Crisis, also referred to as the Messinian Event, is a period when the Mediterranean Sea evaporated partly or completely dry during the
The global trend was one towards increasing aridity caused primarily by global cooling reducing the ability of the atmosphere to absorb moisture. Uplift of East Africa in the Late Miocene was partly responsible for the shrinking of tropical rain forests in that region, and Australia got drier as it entered a zone of low rainfall in the Late Miocene. East Africa is the Easternmost Region of the African Continent. For a topic outline on this subject see List of basic Australia topics.
Life
Flora
Grasslands underwent a major expansion; forests fell victim to a generally cooler and drier climate overall. Grasses also diversified greatly, co-evolving with large herbivores and grazers, including ruminants. In a broad sense biological co-evolution is "the change of a biological object triggered by the change of a related object" Physiologically a ruminant is a Mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first stomach known Between 7 and 6 million years ago, there occurred a sudden expansion of grasses which were able to assimilate carbon dioxide more efficiently but were also richer in silica, causing a worldwide extinction of large herbivores. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide [1]
Fauna
Both marine and continental fauna were fairly modern, although marine mammals were less numerous. Fauna is all of the Animal life of any particular region or time Only in isolated South America and Australia did widely divergent fauna exist. Mammals were also modern, with recognizable wolves, raccoons, horses, beaver, deer, camels, and whales. The grey wolf or gray wolf ( Canis lupus) also known as the timber wolf or simply wolf, is a Mammal of the order Carnivora The horse ( Equus caballus) is a hoofed ( Ungulate) Mammal, one of eight living species of the family Equidae. Beavers are two primarily nocturnal semi-aquatic species of Rodent, one native to North America and one to Europe A deer is a Ruminant Mammal belonging to the family Cervidae. Camels are Even-toed ungulates within the Genus Camelus. The Dromedary, one-humped or Arabian camel has a single hump and the Whales are marine mammals which are neither Dolphins (ie members of the families Delphinidae or Platanistoidae) nor Porpoises Orcas
Recognizable crows, ducks, auks, grouses and owls appear in the Miocene. The true crows are large Passerine Birds that comprise the Genus Corvus in the family Corvidae. For duck as a food see Duck (food; for other meanings see Duck (disambiguation. This article is about a family of birds For the American ornithological journal see The Auk. Grouse are a group of birds from the order Galliformes. Often considered a family Tetraonidae, the American Ornithologists' Union The Owls are an order of birds of prey. Most are Solitary, and nocturnal, with some exceptions (e By the epoch's end, all or almost all modern bird families 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. In Biological classification, family ( Latin Marine birds reached their highest diversity ever in the course of this epoch.
Brown algae, called kelp, proliferate, supporting new species of sea life, including otters, fish and various invertebrates. The Phaeophyceae or brown algae, (singular alga is a large group of mostly marine multicellular Algae including many Seaweeds of colder Kelp are large Seaweeds ( Algae) belonging to the Brown algae and classified in the order Laminariales Otters are semi- aquatic (or in one case aquatic) fish-eating Mammals The otter subfamily Lutrinae forms part of the family Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two An invertebrate is an Animal lacking a Vertebral column. The group includes 98% of all animal Species — all animals except those in the Chordate The cetaceans diversified, and some modern genera appeared, such as the sperm whales. The sperm whale family or simply the sperm whales is the collective name given to three species of Whale found worldwide the Sperm Whale, in the genus The pinnipeds, which appeared near the end of the Oligocene, became more aquatic. Pinnipeds ("fin-feet" lit "winged feet" or fin-footed mammals are a widely distributed and diverse group of semi-aquatic marine Mammals comprising
Approximately 100 species of apes lived during this time. They occupied much of the Old World and ranged in size, diet, and anatomy. The Old World consists of those parts of Earth known to Europeans Asians and Africans in the 15th century Due to scanty fossil evidence it is unclear which ape or apes contributed to the modern hominoid clade, but molecular evidence indicates this ape lived from between 15 to 12 million years ago.
In the oceans, modern sharks appeared at this time including the huge Megalodon. Sharks ( Superorder Selachimorpha) are a type of Fish with a full cartilaginous Skeleton and a highly streamlined body The megalodon (ˡmɛgələˌdɒn or MEG -a-la-don meaning "big tooth" or in Greek as μέγας 'οδόντος was a giant Shark Cetaceans, such as dolphins, whales, and porpoises evolved. The Order Cetacea (sɪˈteɪʃiə L cetus, whale includes Whales Dolphins and Porpoises Cetus is Dolphins are Marine mammals that are closely related to Whales and Porpoises There are almost forty species of dolphin in seventeen genera. Whales are marine mammals which are neither Dolphins (ie members of the families Delphinidae or Platanistoidae) nor Porpoises Orcas Porpoises are Small Cetaceans of the Family Phocoenidae; they are related to Whales and Dolphins They are distinct from dolphins Their ancestors the Archaeoceti, however, were becoming less common and eventually became extinct. Archaeocetes, or " ancient whales " are a Paraphyletic group of Cetaceans that gave rise to the modern cetaceans
Oceans
East Antarctica had some glaciers during the early Miocene (23-15 million years ago). Oceans cooled partly due the formation of ACC, and about 15 million years ago the ice cap in the southern hemisphere started to grow to its present form. The Antarctic Circumpolar Current ( ACC) is an Ocean current that flows from west to east around Antarctica. The Greenland ice cap developed later, in Pliocene time, about 3 million years ago. The Pliocene epoch (spelled Pleiocene in some older texts is the period in the Geologic timescale that extends
Middle Miocene disruption
Footnotes
- ^ Stanley, S. The term Middle Miocene disruption alternatively the Middle Miocene extinction or Middle Miocene extinction peak refers to a wave of extinctions of terrestrial M. Earth system history. New York 1999, 525-6.
See also
- Geologic Time Scale
- List of fossil sites (with link directory)
- Middle Miocene disruption
- Category:Miocene animals
| Neogene period | |||
|---|---|---|---|
| Miocene | Pliocene | Pleistocene | Holocene |
| Aquitanian | Burdigalian Langhian | Serravallian Tortonian | Messinian | Zanclean | Piacenzian (Gelasian) | Gelasian | Early Middle | Late | Boreal | Atlantic |
References
- Ogg, Jim; (2004): Overview of Global Boundary Stratotype Sections and Points (GSSP's). The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other This is a worldwide list of important and/or well-known localities where Fossils have been found The term Middle Miocene disruption alternatively the Middle Miocene extinction or Middle Miocene extinction peak refers to a wave of extinctions of terrestrial The Neogene is a geologic period and system starting 2303 ± 0 The Pliocene epoch (spelled Pleiocene in some older texts is the period in the Geologic timescale that extends The Pleistocene ('plaɪstəsin is the epoch from 18 million to 10000 years BP covering the world's recent period The Holocene is a Geological epoch which began approximately 10000 years ago (about 8000 BC Aquitanian is the first Age of the Miocene Epoch. It spans the time between 23 Burdigalian is a Age of the early Miocene Epoch. It spans the time between 20 Langhian is the older ICS Age of the Middle Miocene epoch. It spans the time between 15 Serravallian is a Age of the middle Miocene epoch that spans the time between 13 Tortonian is a Age of the late Miocene epoch that spans the time between 11 Messinian is the last Age of the Miocene epoch. It spans the time between 7 In the Geologic time scale, the Zanclean (also known as Tabianian, Dacian) is the Age which makes up the Early Pliocene Piacenzian (also known as Astian, Redonian, or Romanian) is a Age of the Pliocene Epoch. The Gelasian is a stage whose belonging to either the Pliocene or the Pleistocene Epochs is currently discussed The Gelasian is a stage whose belonging to either the Pliocene or the Pleistocene Epochs is currently discussed Early Pleistocene (also known as Lower Pleistocene, or Calabrian) is a subdivision of the Pleistocene Epoch of the Geologic time scale So far the Pleistocene Series is not subdivided into formal units (i The Late Pleistocene (also known as Upper Pleistocene or the Tarantian) is a stage of the Pleistocene Epoch. 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. HTML fulltext. Retrieved 2006-APR-30.
- Rohde, Robert A. (2005): GeoWhen Database. Retrieved 2006-SEP-23.
- Cox, C. Barry, and Moore, Peter D. , Biogeography. An ecological and evolutionary approach. Fifth edition, Cambridge 1993 (1998)
External links
Dictionary
Miocene
-adjective
- (geology) Of a geologic epoch within the Neogene period from about 23 to 5.3 million years ago; marked by the drift of continents to their present position.
-proper noun
- (geology) The Miocene epoch.
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