Cenozoic. Mammals are the dominant terrestrial vertebrates of the Cenozoic. The era began 65 million years ago. 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. From a geological perspective, it did not take long for mammals and birds to greatly diversify in the absence of the large reptiles that had dominated during the Mesozoic. Some birds grew larger than the average human.
This group became known as the "terror birds," and were formidable predators. Climate-wise, the Earth had begun a drying and cooling trend, culminating in the glaciations of the Pleistocene Epoch, and partially offset by the Paleocene-Eocene Thermal Maximum. Subdivisions[edit] Tectonics[edit] Iceage under pleistocene (2,59–0,01 million years ago). Climate[edit] Life[edit] See also[edit] Tertiary. Tertiary is an old unofficial but still widely used term for a geologic period from 66 million to 2.588 million years ago, a time span that lies between the superseded Secondary period and the Quaternary.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,[1][2][3][4] its traditional span being divided between the Paleogene and Neogene Periods and the first stage of the Pleistocene 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, and spanned to the beginning of the Quaternary glaciation at the end of the Pliocene Epoch. The Tertiary also included the early Pleistocene. Historical use of the term[edit] In the early development of the study of geology, the periods were thought to correspond to the Biblical narrative, the rocks of the Tertiary being thought to be associated with the Great Flood.[6] Geological events[edit] Paleocene. The Paleocene Epoch brackets two major events in Earth's history.
It started with the mass extinction event at the end of the Cretaceous, known as the Cretaceous-Paleogene (K-Pg) boundary. This was a time marked by the demise of non-avian dinosaurs, giant marine reptiles and much other fauna and flora. The die-off of the dinosaurs left unfilled ecological niches worldwide. It ended with the Paleocene-Eocene Thermal Maximum. This was a geologically brief (~0.2 million year) interval characterized by extreme changes in climate and carbon cycling. The name "Paleocene" comes from Greek and refers to the "old(er)" (παλαιός, palaios) "new" (καινός, kainos) fauna that arose during the epoch.[3] Boundaries and subdivisions[edit] Climate[edit] The early Paleocene was cooler and dryer than the preceding Cretaceous, though temperatures rose sharply during the Paleocene–Eocene Thermal Maximum.
Paleogeography[edit] Oceans[edit] Warm seas circulated throughout the world, including the poles. Flora[edit] Primate. A primate ( With the exception of humans, which inhabit every continent,[a] most primates live in tropical or subtropical regions of the Americas, Africa and Asia.[5] 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). Based on fossil evidence, the earliest known true primates, represented by the genus Teilhardina, date to 55.8 million years old.[6] An early close primate relative known from abundant remains is the Late Paleocene Plesiadapis, circa 55–58 million years old.[7] Molecular clock studies suggest that the primate branch may be even older, originating in the mid-Cretaceous period around 85 mya.[7] Considered generalist mammals, primates exhibit a wide range of characteristics.
Some primates (including some great apes and baboons) are primarily terrestrial rather than arboreal, but all species possess adaptations for climbing trees. Historical and modern terminology[edit] Eocene. The Eocene /ˈiːəsiːn/ (symbol Eo [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 a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C. 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. Subdivisions[edit] Climate[edit] Atmospheric greenhouse gas evolution[edit] Large lakes[edit] Oligocene. The Oligocene is often considered an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene.[4] Major changes during the Oligocene included a global expansion of grasslands, and a regression of tropical broad leaf forests to the equatorial belt.
The start of the Oligocene is marked by a notable extinction event called the Grande Coupure; it featured the replacement of European fauna with Asian fauna, except for the endemic rodent and marsupial families. By contrast, the Oligocene–Miocene boundary is not set at an easily identified worldwide event but rather at regional boundaries between the warmer late Oligocene and the relatively cooler Miocene. Subdivisions[edit] Oligocene faunal stages from youngest to oldest are: Climate[edit] The Paleogene period general temperature decline is interrupted by an Oligocene 7 million year stepwise climate change.
Paleogeography[edit] Flora[edit] Fauna[edit] Oceans[edit] Poaceae. Grasslands such as savannah and prairie where grasses are dominant are estimated to constitute 40.5% of the land area of the Earth, excluding Greenland and Antarctica.[6] Grasses are also an important part of the vegetation in many other habitats, including wetlands, forests and tundra. The Poaceae are the most economically important plant family, providing staple foods from domesticated cereal crops such as maize (corn), wheat, rice, barley, and millet as well as forage, building materials (bamboo, thatch, straw) and fuel (ethanol). Etymology[edit] Evolutionary history[edit] Grasses include some of the most versatile plant life-forms.
Prior to 2005, fossil findings indicated that grasses evolved around 55 million years ago. Description[edit] Diagram of a typical lawn grass plant. Growth and development[edit] Grass blades grow at the base of the blade and not from elongated stem tips. Distribution[edit] Ecology[edit] Taxonomy[edit] Uses[edit] Food production[edit] Industry[edit] Sports turf[edit] Miocene. The Miocene /ˈmaɪəsiːn/ (symbol MI[1]) is the first 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”)[2] and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene epoch and is followed by the Pliocene epoch.
The earth went from the Oligocene through the Miocene and into the Pliocene as it cooled into a series of ice ages. The apes arose and diversified during the Miocene epoch, becoming widespread in the Old World. Subdivisions[edit] The Miocene faunal stages from youngest to oldest are typically named according to the International Commission on Stratigraphy:[5] Paleogeography[edit] Continents continued to drift toward their present positions. Mountain building took place in western North America, Europe, and East Asia.
Climate[edit] Life[edit] Pliocene. 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 Pleistocene. The upper boundary was set at the start of the Pleistocene glaciations. Etymology[edit] The Pliocene was named by Sir Charles Lyell. Subdivisions[edit] Piacenzian (3.600–2.588 Ma)Zanclean (5.332–3.600 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 (4.75–1.806 Ma).
Climate[edit] Mid-Pliocene reconstructed annual sea surface temperature anomaly Paleogeography[edit] Sea level changes exposed the land-bridge between Alaska and Asia. Flora[edit] Titanis. Hominidae. The Hominidae (/hɒˈmɪnɨdiː/; also known as great apes[notes 1]) form a taxonomic family of primates, including four extant genera: 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 most recent common ancestor of the Hominidae lived roughly 14 million years ago,[3] when the ancestors of the orangutans speciated from the ancestors of the other three genera.[4] The ancestors of the Hominidae family had already speciated from those of the Hylobatidae family, perhaps 15 million to 20 million years ago.[4][5] History[edit] Taxonomic history[edit] The classification of the great apes has been revised several times in the last few decades. Especially close human relatives form a subfamily, the Homininae. Quaternary. This relatively short geological period is characterized by a series of glaciations and by the appearance and expansion of anatomically modern humans. 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.
Research history[edit] The Quaternary Period follows the Neogene Period and extends to the present. The Quaternary covers the time span of glaciations classified as the Pleistocene, and includes the present interglacial period, the Holocene. This places the start of the Quaternary at the onset of Northern Hemisphere glaciation approximately 2.6 million years ago. Prior to 2009, the Pleistocene was defined to be from 1.805 million years ago to the present, so the current definition of the Pleistocene includes a portion of what was, prior to 2009, defined as the Pliocene. Geology[edit] Climate[edit] Quaternary glaciation[edit] Pleistocene. 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";[2] 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.
Dating[edit] The Pleistocene covers the recent period of repeated glaciations. The name Plio-Pleistocene has in the past been used to mean the last ice age. Paleogeography and climate[edit] Glacial features[edit] The effects of glaciation were global. Major events[edit] Holocene. 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.
Given these, a new term Anthropocene, is specifically proposed and used informally only for the very latest part of modern history and of significant human impact since the epoch of the Neolithic Revolution (around 12,000 years BP). Overview[edit] Note: "ka" means "thousand years" (non-calibrated C14 dates) Paleontologists have defined no faunal stages for the Holocene.
If subdivision is necessary, periods of human technological development, such as the Mesolithic, Neolithic, and Bronze Age, are usually used. Geology[edit] Climate[edit] Human. Humans began to practice sedentary agriculture about 12,000 years ago, domesticating plants and animals which allowed for the growth of civilization. Humans subsequently established various forms of government, religion, and culture around the world, unifying people within a region and leading to the development of states and empires.
The rapid advancement of scientific and medical understanding in the 19th and 20th centuries led to the development of fuel-driven technologies and improved health, causing the human population to rise exponentially. By 2012 the global human population was estimated to be around 7 billion.[10][11] Etymology and definition In common usage, the word "human" generally refers to the only extant species of the genus Homo — anatomically and behaviorally modern Homo sapiens. Its usage often designates differences between the species as a whole and any other nature or entity.
History Evolution and range Evidence from molecular biology Evidence from the fossil record.