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Mammals are the dominant terrestrial vertebrates of the Cenozoic. The Cenozoic Era ( pron.: / ˌ s ɛ n ə ˈ z oʊ . ɨ k / or / ˌ s iː n ə ˈ z oʊ . ɨ k / ; also Cænozoic , Caenozoic or Cainozoic ; meaning "new life", from Greek καινός kainos "new", and ζωή zoe "life") is the current and most recent of the three Phanerozoic geological eras , following the Mesozoic Era and covering the period from 66 million years ago to the present. The era began in the wake of the Cretaceous–Paleogene extinction event (K-Pg event) at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs (as well as other terrestrial and marine flora and fauna) at the end of the Mesozoic. The Cenozoic is also known as the Age of Mammals , because the extinction of many groups allowed mammals to greatly diversify. Early in the Cenozoic, following the K-Pg event, the planet was dominated by relatively small fauna, including small mammals, birds, reptiles, and amphibians.
Tertiary is an officially deprecated but still widely used term for a geologic period from 65 million to 2.6 million years ago, a time span that lies between the superseded Secondary period and the Quaternary . The Tertiary is no longer recognized as a formal unit by the International Commission on Stratigraphy , [ 4 ] its traditional span being divided between the Paleogene and Neogene Periods of the Cenozoic Era. The period began with the demise of the non- avian dinosaurs in the Cretaceous–Paleogene extinction event , at the start of the Cenozoic Era , spanning to the beginning of the most recent ice age at the end of the Pliocene Epoch . The Tertiary also included the early Pleistocene . [ edit ] Historical use of the term The term Tertiary was first used by Giovanni Arduino during the mid-18th century.
The Paleocene (symbol P ε [ 2 ] ) or Palaeocene , the "early recent", is a geologic epoch that lasted from about 66 to 56 million years ago . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era . As with most other older geologic periods , the strata that define the epoch's beginning and end are well identified but the exact date of the end is uncertain. The Paleocene Epoch immediately followed the mass extinction event at the end of the Cretaceous , known as the Cretaceous–Paleogene boundary , which marks the demise of non-avian dinosaurs , the giant marine reptiles and much other fauna and flora . The die-off of the dinosaurs left unfilled ecological niches worldwide, and the name "Paleocene" comes from Greek and refers to the "old(er)" ( παλαιός , palaios ) – "new" ( καινός , kainos ) fauna that arose during the epoch, before modern [ clarification needed — see Talk ] mammalian orders emerged in the Eocene .
A primate ( i / ˈ p r aɪ m eɪ t / PRY -mayt ) is a mammal of the order Primates ( i / p r aɪ ˈ m eɪ t iː z / pry- MAY -teez ; Latin : "prime, first rank"), [ 2 ] which contains prosimians and simians . [ 3 ] Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment. All but a few primate species remain at least partly arboreal . With the exception of humans , who inhabit every continent, [a] most primates live in tropical or subtropical regions of the Americas, Africa and Asia. [ 4 ] They range in size from Madame Berthe's mouse lemur , which weighs only 30 g (1 oz), to the eastern lowland gorilla , weighing over 200 kg (440 lb).
The Eocene (symbol E o [ 2 ] ) epoch, lasting from 56 to 33.9 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 Eocene is marked by the emergence of the first modern mammals . [ clarification needed — see Talk ] The end is set at a major extinction event called the Grande Coupure (the "Great Break" in continuity) or the Eocene–Oligocene extinction event , which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay . As with other geologic periods , the strata that define the start and end of the epoch are well identified, [ 3 ] though their exact dates are slightly uncertain. The name Eocene comes from the Greek ἠώς ( eos , dawn ) and καινός ( kainos , new) and refers to the "dawn" of modern ('new') fauna that appeared during the epoch.
The Oligocene (symbol O G [ 2 ] ) is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present ( 33.9 ± 0.1 to 23.03 ± 0.05 Ma ). 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 uncertain. The name Oligocene comes from the Greek ὀλίγος ( oligos , few) and καινός ( kainos , new), and refers to the sparsity of additional modern mammalian species of fauna after a burst of evolution during the Eocene . The Oligocene follows the Eocene Epoch and is followed by the Miocene Epoch.
The Poaceae (also called Gramineae or true grasses ) are a large and nearly ubiquitous family of monocotyledonous flowering plants . With more than 10,000 domesticated and wild species, the Poaceae represent the fifth-largest plant family , following the Orchidaceae , Asteraceae , Fabaceae , and Rubiaceae . [ 2 ] Though commonly called "grasses", seagrasses , rushes , and sedges fall outside this family. The rushes and sedges are related to the Poaceae, being members of the order Poales , but the seagrasses are members of order Alismatales . Grasslands are estimated to compose 20% of the vegetation cover of the Earth . Poaceae live in many other habitats, including wetlands , forests , and tundra .
The Miocene (symbol M I [ 1 ] ) is a geological epoch of the Neogene Period and extends from about 23.03 to 5.332 million years ago (Ma). The Miocene was named by Sir Charles Lyell . Its name comes from the Greek words μείων ( meiōn , “less”) and καινός ( kainos , “new”) and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene .
The Pliocene ( pron.: / ˈ p l aɪ . ə s iː n / ; archaically Pleiocene ) Epoch (symbol P O [ 1 ] ) is the period in the geologic timescale that extends from 5.332 million to 2.588 [ 2 ] 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 Hominidae ( pron.: / h ɒ ˈ m ɪ n ɨ d iː / ; also known as great apes [ notes 1 ] ) form a taxonomic family of primates, including four extant genera : chimpanzees and bonobos ( Pan ), [ notes 2 ] gorillas ( Gorilla ), humans ( Homo ), and orangutans ( Pongo ). [ 1 ] The term "hominid" is also used in the more restricted sense as hominins or "humans and relatives of humans closer than chimpanzees". [ 2 ] In this usage, all hominid species other than Homo sapiens are extinct . A number of known extinct genera are grouped with humans in the Homininae subfamily, others with orangutans in the Ponginae subfamily.
The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS . [ 4 ] It follows the Neogene Period and spans from 2.588 ± 0.005 million years ago to the present. The relatively short period is characterized by a series of glaciations and by the appearance and expansion of anatomically modern humans . The Quaternary includes two geologic epochs : the Pleistocene and Holocene . A proposed but as yet informal third epoch, the Anthropocene , has also gained credence as the time in which humans began to profoundly affect and change the global environment, although its start date is still disputed. [ edit ] Research history The term Quaternary ("fourth") was proposed by Giovanni Arduino in 1759 for alluvial deposits in the Po River valley in northern Italy .
The Pleistocene ( pron.: / ˈ p l aɪ s t ə s iː n / ) (symbol P S [ 1 ] ) is the geological epoch which lasted from about 2,588,000 to 11,700 years ago, spanning the world's recent period of repeated glaciations . Sir Charles Lyell introduced this term in 1839 to describe strata in Sicily that had at least 70% of their molluscan fauna still living today. This distinguished it from the older Pliocene Epoch , which Lyell had originally thought to be the youngest fossil rock layer. He constructed the name "Pleistocene" ("Most New" or "Newest") from the Greek πλεῖστος, pleīstos , "most", and καινός, kainós ( latinized as cænus ), "new"; this contrasting with the immediately preceding Pleiocene ("More New" or "Newer", from πλείων, pleíōn , "more", and kainós ; usual spelling: Pliocene), and the immediately subsequent Holocene ("wholly new" or "entirely new", from ὅλος, hólos , "whole", and kainós ) epoch , which extends to the present time.
The Holocene is a geological epoch which began at the end of the Pleistocene [ 1 ] (around 12,000 to 11,500 14 C years ago) and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words ὅλος ( holos , whole or entire) and καινός ( kainos , new), meaning "entirely recent". It has been identified with the current warm period, known as MIS 1 and based on that past evidence, can be considered an interglacial in the current ice age . The Holocene also encompasses within it the growth and impacts of the human species world-wide, including all its written history and overall significant transition toward urban living in the present. Human impacts of the modern era on the Earth and its ecosystems may be considered of global significance for future evolution of living species, including approximately synchronous lithospheric evidence, or more recently atmospheric evidence of human impacts.
Humans ( Homo sapiens ) are primates of the family Hominidae , and the only extant species of the genus Homo . [ 2 ] [ 3 ] [ 4 ] Humans are characterized by having a large brain relative to body size, with a particularly well developed neocortex , prefrontal cortex and temporal lobes , making them capable of abstract reasoning , language , introspection , problem solving and culture through social learning.