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Encyclopedia > Geologic timescale

The geologic time scale is used by geologists and other scientists to describe the timing and relationships between events that have occurred during the history of the Earth. The table of geologic periods presented here is in accordance with the dates and nomenclature proposed by the International Commission on Stratigraphy, and uses the standard color codes of the United States Geologic Survey. A geologist is a contributor to the science of geology. ... History Forums - History is Happening -Discuss all historical topics, as well as current events, in an academic setting. ... Earth, also known as the Earth, Terra, and (mostly in the 19th century) Tellus, is the third planet outward from the Sun. ... In geology, a period or age is a time span of many millions of years that are assumed to have had similar characteristics. ... Nomenclature is a system of naming and categorizing objects in a given category. ... The International Commission on Stratigraphy concerns itself with stratigraphy on a global scale. ... The United States Geological Survey (USGS) is a scientific agency of the United States government. ...


The Earth is thought by geologists to be about 4,570 million years old. The geologic or "deep" time of Earth's past has been organized into various units according to events which took place in each period. Different spans of time on the time scale are usually delimited by major geologic or paleontologic events, such as mass extinctions. For example, the boundary between the Cretaceous period and the Palaeogene period is defined by the extinction event that marked the demise of the dinosaurs and of many marine species. Earth, also known as the Earth, Terra, and (mostly in the 19th century) Tellus, is the third planet outward from the Sun. ... Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. ... A paleontologist carefully chips rock from a column of dinosaur vertebrae. ... An extinction event (also extinction-level event, ELE) is a period in time when a large number of species die out. ... The Cretaceous period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic period (about 135 mya) to the beginning of the Paleocene epoch of the Tertiary period (65 mya). ... Palaeogene (alternatively Paleogene) period is a unit of geologic time that began 65 and ended 23 million years ago. ... The Cretaceous-Tertiary (K-T or KT) extinction event, also known as the KT boundary, was a period of massive extinction of species, about 65. ... Orders Saurischia    Sauropodomorpha    Theropoda Ornithischia Dinosaurs are animals that dominated the terrestrial ecosystem for over 100 million years. ... In biology, a species is, loosely speaking, a group of related organisms that share a more or less distinctive form and are capable of interbreeding. ...

Contents


Terminology

The largest defined unit is the Eon. Eons are divided into Eras, which are in turn divided into Periods, Epochs and Stages. At the same time, paleontologists define a system of faunal stages, of varying lengths, based changes in the observed fossil assemblages. In many cases, such faunal stages have been adopted in building the geologic nomenclature, though in general there are far more recognized faunal stages than defined geologic time units. In general usage, an eon (also spelled Aeon) is a very long period of time. ... Faunal stages are a subdivision of geologic time used primarily by paleontologists who study fossils rather than by geologists who study rock formations. ...


Geologists tend to talk in terms of Upper/Late, Lower/Early and Middle parts of periods and other units -- e.g. "Upper Jurassic", "Middle Cambrian". Because geologic units occurring at the same time but from different parts of the world can often look different and contain different fossils, there are many examples where the same period of time was historically given different names in different locales. For example, in North America the Early Cambrian is refered to as the Waucoban series that is then subdivided into zones based on trilobites. The same timespan is split into Tommotian, Atdabanian and Botomian stages in East Asia and Siberia. It is a key aspect of the work of the International Commission on Stratigraphy to reconcile this conflicting terminology and define universal horizons that can be used around the world. A geologist is a contributor to the science of geology. ... The Jurassic period is a major unit of the geologic timescale that extends from about 200 million years BP at the end of the Triassic to 146 million years BP at the beginning of the Cretaceous. ... The Cambrian is a major division of the geologic timescale that begins about 542 million years before the present (BP) at the end of the Proterozoic eon and ended about 490 million years BP with the beginning of the Ordovician period. ... It has been suggested that Northern America be merged into this article or section. ... The Cambrian is a major division of the geologic timescale that begins about 542 million years before the present (BP) at the end of the Proterozoic eon and ended about 490 million years BP with the beginning of the Ordovician period. ... Orders Agnostida Redlichiida Corynexochida Lichida Nektaspida? Phacopida Proetida Asaphida Harpetida Ptychopariida Trilobites are extinct arthropods in the class Trilobita. ... East Asia can be defined in either cultural or geographic terms. ... Siberia Siberia (Russian: , common English transliterations: Sibir’, Sibir; from the Tatar for “sleeping land”) is a vast region of Russia and northern Kazakhstan constituting almost all of northern Asia. ...


History of the Time Scale

The principles underlying geologic time scales were laid down by Nicholas Steno in the late 17th century. Steno argued that rock layers (strata) are laid down in succession, and that each represents a "slice" of time. He also formulated the principle of superposition, which states that any given stratum is probably older than those above it and younger than those below it, was also formulated and popularized by Steno. Steno's principles were simple; applying them to real rocks proved complex. Over the course of the 18th century geologists came to realize that: 1) Sequences of strata were often eroded, distorted, tilted, or even inverted after deposition; 2) Strata laid down at the same time in different areas could have entirely different appearances; 3) The strata of any given area represented only part of the Earth's long history. Nicolaus Steno. ... In physics, the principle of superposition states that the net displacement at a given place and time caused by two or more waves traversing the same space is the vector sum of the displacements which would have been produced by the individual waves separately. ...


The first serious attempts to formulate a geological time scale that could be applied anywhere on Earth took place in the late 18th century. The most influential of those early attempts (championed by Abraham Werner, among others) divided the rocks of the Earth's crust into four types: Primary, Secondary, Tertiary, and Quaternary. Each type of rock, according to the theory, formed during a specific period in Earth history. It was thus possible to speak of a "Tertiary Period" as well as of "Tertiary Rocks." Indeed, "Tertiary" and "Quaternary" remained in use as names of geological periods well into the 20th century. Abraham Gottlob Werner Abraham Gottlob Werner (1749 or 1750 - 1817), was born in Wehrau, a city in Prussian Silesia, southeastern Germany. ...


The identification of strata by the fossils they contained, pioneered by William Smith, Georges Cuvier, and Alexandre Brogniart in the early 19th century, enabled geologists to divide Earth history more finely and precisely. It also enabled them to correllate strata across national (or even continental) boundaries. If two strata (however distant in space or different in composition) contained the same fossils, chances were good that they had been laid down at the same time. Detailed studies of the strata and fossils of Europe produced, between 1820 and 1850, the sequence of geological periods still used today. People William Smith (1769-1839), geologist William Smith (1728-1814), Representative for Maryland from 1789 to 1890 William Smith (1751-1837), Representative for South Carolina from 1797 to 1798 William Smith (1762-1840), Senator from South Carolina from 1815 to 1830 William Smith, Representative for Virginia from 1821 to 1824... Georges Cuvier Baron Georges Léopold Chrétien Frédéric Dagobert Cuvier (August 23, 1769 - May 13, 1832) was a French naturalist and zoologist. ...


British geologists dominated the process, and the names of the periods reflect that dominance. The "Cambrian," "Ordivician," and "Silurian" periods were named for ancient British tribes (and defined using stratigraphic sequences from Wales and Scotland). The "Devonian" was named for the British county of Devon, and the name "Carboniferous" was simply an adaptation of "the Coal Measures," the old British geologists' term for the same set of strata. The "Permian," though defined using strata in Russia, was delineated and named by a British geologist: Roderick Murchison. The next three periods in the sequence . . . Devon is a county in South West England, bordering on Cornwall to the west, Dorset and Somerset to the east. ... Sir Roderick Murchison Sir Roderick Impey Murchison (February 19, 1792 – October 22, 1871), was an influential Scottish geologist who first described and investigated the Silurian era. ...


British geologists were also responsible for the grouping of periods into Eras and the subdivision of the Tertiary and Quaternary periods into epochs.


When William Smith and Sir Charles Lyell first recognized that rock strata represented successive time periods, there was no way to determine what time scale they represented. Creationists proposed dates of only a few thousand years, while others suggested large (and even infinite) ages. For over 100 years, the age of the Earth and of the rock strata was the subject of considerable debate until advances in the latter part of the 20th century allowed radioactive dating to provide relatively firm dates to geologic horizons. In the intervening century and a half, geologists and paleontologists constructed time scales based solely on the relative positions of different strata and fossils. William Smith. ... Charles Lyell Sir Charles Lyell (November 14, 1797 – February 22, 1875), British geologist, and popularizer of uniformitarianism. ... Interstate road cut through limestone and shale strata in eastern Tennessee In geology and related fields, a stratum (plural: strata) is a layer of rock or soil with internally consistent characteristics that distinguishes it from contiguous layers. ... Creationism is generally the belief that the universe was created by a deity, or alternatively by one or more powerful and intelligent beings. ... Earth, also known as the Earth, Terra, and (mostly in the 19th century) Tellus, is the third planet outward from the Sun. ... Radiometric dating is a technique used to date materials based on a knowledge of the decay rates of naturally occurring isotopes, and the current abundances. ...


In 1977, the Global Commission on Stratigraphy (now the International Commission) started an effort to define global references (GSSPs) for geologic periods and faunal stages. Their most recent work is described in the 2004 geologic time scale of Gradstein et al. (ISBN 0521786738), and used as the foundation of this page. GSSP stands for Global Stratigraphic Section and Point. ...


Table of geologic time

Eon Era Period1 Series/
Epoch
Major Events End, Million
Years Ago2
Phanerozoic Cenozoic Neogene3 Holocene End of recent glaciation and rise of modern civilization Ongoing
Pleistocene Flourishing and then extinction of many large mammals (Pleistocene megafauna); Evolution of fully modern humans 0.011430 ± 0.00013
Pliocene Intensification of present ice age. Cool and dry climate; Australopithecines appear, many of the existing genera of mammals, and recent molluscs appear 1.806 ± 0.005 *
Miocene Moderate climate; Mountain building in northern hemisphere; Modern mammal and bird families became recognizable. Horses and mastodonts diverse. Grasses become ubiquitous. First hominoids appear. 5.332 ± 0.005 *
Paleogene3 Oligocene Warm climate; Rapid evolution and diversification of fauna, especially mammals. Major evolution and dispersal of modern types of angiosperms 23.03 ± 0.05 *
Eocene Archaic mammals (e.g. Creodonts, Condylarths, Uintatheres, etc) flourish and continue to develop during the epoch. Appearance of several "modern" mammal families. Primitive whales diversify. First grasses. Reglaciation of Antarctica; start of current ice age. 33.9 ± 0.1 *
Paleocene Climate tropical. Modern plants; Mammals diversify into a number of primitive lineages following the extinction of the dinosaurs. First large mammals (up to bear or small hippo size) 55.8 ± 0.2 *
Mesozoic Cretaceous Upper/Late Flowering plants appear, along with new types of insects. More modern teleost fish begin to appear. Ammonites, belemnites, rudists, echinoids and sponges all common. Many new types of dinosaurs (e.g. Tyrannosaurs, Titanosaurs, duck bills, and horned dinosaurs) evolve on land, as do modern crocodilians; and mosasaurs and modern sharks appear in the sea. Primitive birds gradually replace pterosaurs. Monotremes, marsupials and placental mammals appear. Break up of Gondwana. 65.5 ± 0.3 *
Lower/Early 99.6 ± 0.9 *
Jurassic Upper/Late Gymnosperms (especially conifers, Bennettitales and cycads) and ferns common. Many types of dinosaurs, such as sauropods, carnosaurs, and stegosaurs. Mammals common but small. First birds and lizards. Ichthyosaurs and plesiosaurs diverse. Bivalves, Ammonites and belemnites abundant. Echinoids very common, also crinoids, starfish, sponges, and terebratulid and rhynchonellid brachiopods. Breakup of Pangea into Gondwana and Laurasia. 145.5 ± 4.0
Middle 161.2 ± 4.0
Lower/Early 175.6 ± 2.0 *
Triassic Upper/Late Archosaurs dominant and diverse on land, include many large forms; cynodonts become smaller and more mammal-like. First dinosaurs, mammals, pterosaurs, and crocodilia. Dicrodium flora common on land. Many large aquatic temnospondyl amphibians. Ichthyosaurs and nothosaurs common in the seas. Ceratite ammonoids extremely common. Modern corals and teleost fish appear. 199.6 ± 0.6
Middle 228.0 ± 2.0
Lower/Early 245.0 ± 1.5
Paleozoic Permian Lopingian Landmass unites in the supercontinent of Pangea. Synapsid reptiles become common (Pelycosaurs and Therapsids), parareptiles and temnospondyl amphibians also remain common. Carboniferous flora replaced by gymnosperms in the middle of the period. Beetles and flies evolve. Marine life flourishes in the warm shallow reefs. Productid and spriferid brachiopods, bivalves, foraminifera, and ammonoids all abundant. End of Permo-carboniferous ice age. At the end of the period the Permian extinction event- 95% of life on Earth becomes extinct 251.0 ± 0.4 *
Guadalupian 260.4 ± 0.7 *
Cisuralian 270.6 ± 0.7 *
Carbon-
iferous
4
Pennsyl-
vanian
Upper/Late Winged insects appear and are abundant, some growing to large size. Amphibians common and diverse. First reptiles, coal forests (Lepidodendron, Sigillaria, Calamites, Cordaites, etc), very high atmospheric oxygen content. In the seas, Goniatites, brachiopods, bryozoa, bivalves, corals, etc all common. 299.0 ± 0.8 *
Middle 306.5 ± 1.0
Lower/Early 311.7 ± 1.1
Missis-
sippian
Upper/Late Large primitive trees, first land vertebrates, brackish water and amphibious eurypterids; rhizodonts dominant fresh-water predators. In the seas primitive sharks common and very diverse, echinoderms (especially crinoids and blastoids) abundant, Corals, bryozoa, and and brachiopods (Productida, Spriferida, etc) very common; Goniatites common, trilobites and nautiloids in decline. Glaciation in East Gondwana. 318.1 ± 1.3 *
Middle 326.4 ± 1.6
Lower/Early 345.3 ± 2.1
Devonian Upper/Late First clubmosses and horsetails appear, progymnosperms (first seed bearing plants) appear, first trees (Archaeopteris). In the sea strophomenid and atrypid brachiopods, rugose and tabulate corals, and crinoids are abundant. Goniatite ammonoids are common, and coleoids appear. Trilobites reduced in numbers. Ostracoderms decline; Jawed fish (Placoderms, lobe-finned and ray-finned fish, and early sharks) important life in the sea. First amphibians (but still aquatic). "Old Red Continent" (Euramerica) 359.2 ± 2.5 *
Middle 385.3 ± 2.6 *
Lower/Early 397.5 ± 2.7 *
Silurian Pridoli First vascular land plants, millipedes and arthropleurids, first jawed fish, as well as many types of armoured jawless forms. sea-scorpions reach large size. tabulate and rugose corals, brachiopods (Pentamerida, Rhynchonellida, etc), and crinoids all abundant; trilobites and molluscs diverse. Graptolites not as varied. 416.0 ± 2.8 *
Ludlow 418.7 ± 2.7 *
Wenlock 422.9 ± 2.5 *
Llandovery 428.2 ± 2.3 *
Ordovician Upper/Late Invertebrates very diverse and include many new types. Early corals, Brachiopods (Orthida, Strophomenida, etc), bivalves, nautiloids, trilobites, ostracods, bryozoa, many types of echinoderms (cystoids, crinoids, starfish, etc), branched graptolites, and other taxa all common. Conodonts were primitive planktonic vertebrates that appear at the start of the Ordovician. Ice age at the end of the period. First very primitive land plants. 443.7 ± 1.5 *
Middle 460.9 ± 1.6 *
Lower/Early 471.8 ± 1.6
Cambrian Furongian Major diversification of life in the Cambrian Explosion; more than half of modern animal phyla appear, along with a number of extinct and problematic forms. Archeocyatha abundant in the early Cambrian. Trilobites, Priapulida, sponges, inarticulate brachiopods, and many other forms all common. First vertebrates appear. anomalocarids are top predators. Edicarian animals rare, then die out. 488.3 ± 1.7 *
Middle 501.0 ± 2.0 *
Lower/Early 513.0 ± 2.0
Proterozoic5 Neo-
proterozoic
Ediacaran First multi-celled animals. Edicarian fauna (vendobionta flourish worldwide. Simple trace fossils from worm-like animals. First sponges. 542.0 ± 1.0 *
Cryogenian Possible snowball Earth period, Rodinia begins to break up 630 +5/-30 *
Tonian First acritarch radiation 850 6
Meso-
proterozoic
Stenian Formation of Rodinia 1000 6
Ectasian   1200 6
Calymmian   1400 6
Paleo-
proterozoic
Statherian First complex single-celled life 1600 6
Orosirian Transition to oxygen atmosphere 1800 6
Rhyacian   2050 6
Siderian   2300 6
Archaean5 Neoarchean Stabilization of most modern cratons, possible mantle overturn event 2500 6
Mesoarchean First stromatolites 2800 6
Paleoarchean First known oxygen producing bacteria 3200 6
Eoarchean Simple single-celled life 3600 6
Hadean5,7 4100 MYA - Oldest known rock;
4400 MYA - Oldest known mineral;
4570 MYA - Formation of Earth
3800
  1. Paleontologists often refer to faunal stages rather than geologic periods. The stage nomenclature is quite complex. See Harland for an excellent time ordered list of faunal stages.
  2. Dates are slightly uncertain with differences of a few percent between various sources being common. This is largely due to uncertainties in radiometric dating and the problem that deposits suitable for radiometric dating seldom occur exactly at the places in the geologic column where they would be most useful. The dates and errors quoted above are according to the International Commission on Stratigraphy 2004 time scale. Dates labeled with a * indicate boundaries where a Global Boundary Stratotype Section and Point has been internationally agreed upon.
  3. Historically, the Cenozoic has been divided up into the Quaternary and Tertiary sub-eras, as well as the Neogene and Paleogene periods. However, the International Commission on Stratigraphy has recently decided to stop endorsing the terms Quaternary and Tertiary as part of the formal nomenclature.
  4. In North America, the Carboniferous is subdivided into Mississippian and Pennsylvanian Periods.
  5. The Proterozoic, Archean and Hadean are often collectively referred to as Precambrian Time, and sometimes also as the Cryptozoic.
  6. Defined by absolute age (Global Standard Stratigraphic Age).
  7. Though commonly used, the Hadean is not a formal eon and no lower bound for the Eoarchean has been agreed upon. The Hadean has also sometimes been called the Priscoan.

In general usage, an eon (also spelled Aeon) is a very long period of time. ... The Phanerozoic (occasionally Phaenerozoic) Eon is the period of geologic time during which abundant animal life has existed. ... The Cenozoic Era (sometimes still Caenozoic in the United Kingdom) is the most recent of the four Categories: Cenozoic ... Neogene Period: A unit of geologic time consisting of the Miocene and Pliocene Epochs. ... The Holocene Epoch is a geologic period that extends from the present back about 10,000 radiocarbon years. ... Variations in CO2, temperature and dust from the Vostok ice core over the last 400 000 years For the animated movie, see Ice Age (movie). ... A civilization or civilisation has a variety of meanings related to human society. ... The Pleistocene Epoch is part of the geologic timescale, usually dated as 1. ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals characterized by the presence of mammary glands... Binomial name Homo sapiens Linnaeus, 1758 Subspecies Homo sapiens idaltu (extinct) Homo sapiens sapiens Human beings define themselves in biological, social, and spiritual terms. ... The Pliocene epoch is the period in the geologic timescale that extends from 5. ... Variations in CO2, temperature and dust from the Vostok ice core over the last 400 000 years For the animated movie, see Ice Age (movie). ... Species A. afarensis (Lucy) A. africanus A. anamensis A. garhi Formerly Australopithecus, now Paranthropus Australopithecines (genus Australopithecus) are a group of extinct hominids that are closely related to humans. ... Classes Caudofoveata Aplacophora Polyplacophora - Chitons Monoplacophora Bivalvia - Bivalves Scaphopoda - Tusk shells Gastropoda - Snails and Slugs Cephalopoda - Squids, Octopuses, etc. ... The Miocene epoch is a period of time that extends from about 23 to 5. ... In geology, orogeny is the process of mountain building. ... The Northern Hemisphere is the half of a planets surface (or celestial sphere) that is north of the equator (the word hemisphere literally means half ball). On Earth, the Northern Hemisphere contains most of the land and population. ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals characterized by the presence of mammary glands... Orders Many - see section below. ... Species - Donkey - Domestic Horse - Grevys Zebra - Onager - Przewalskis Horse - Plains Zebra - Mountain Zebra Equidae is the family of horse-like animals, order Perissodactyla. ... Mastodon is also a Heavy Metal Band. ... In popular language grass means a short, green, ground covering or lawn, usually, but not necessarily comprised of a true grass or grasses, called turf. ... Families Hylobatidae Hominidae Apes are the members of the Hominoidea superfamily of primates, including humans. ... Palaeogene (alternatively Paleogene) period is a unit of geologic time that began 65 and ended 23 million years ago. ... The Oligocene epoch is a geologic period of time that extends from about 34 million to 23 million years before the present. ... Charles Darwin, father of the theory of evolution by natural selection. ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals characterized by the presence of mammary glands... Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants (also angiosperms or Magnoliophyta) are one of the major groups of modern plants, comprising those that produce seeds in specialized reproductive organs called flowers, where the ovulary or carpel is enclosed. ... The Eocene epoch (56-34 MYA) is a major division of the geologic timescale and the second epoch of the Palaeogene period in the Cenozoic era. ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals characterized by the presence of mammary glands... Families Oxyaenidae Hyaenodontidae The creodonts were an extinct order of mammals that lived from the Paleocene to the Pliocene. ... Condylarthra is an order of Paleocene mammals. ... Suborders Mysticeti Odontoceti (see text) The order Cetacea includes whales, dolphins and porpoises. ... The Paleocene epoch (65-56 MYA) (early dawn of the recent) is the first geologic epoch of the Palaeogene period in the modern Cenozoic era. ... Divisions Land plants (embryophytes) Non-vascular plants (bryophytes) Hepatophyta - liverworts Anthocerophyta - hornworts Bryophyta - mosses Vascular plants (tracheophytes) Lycopodiophyta - clubmosses Equisetophyta - horsetails Pteridophyta - true ferns Psilotophyta - whisk ferns Ophioglossophyta - adderstongues Seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta - flowering plants Adiantum pedatum (a fern... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals characterized by the presence of mammary glands... The Mesozoic is one of three geologic eras of Phanerozoic eon. ... The Cretaceous period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic period (about 135 mya) to the beginning of the Paleocene epoch of the Tertiary period (65 mya). ... The Cretaceous period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic period (about 135 mya) to the beginning of the Paleocene epoch of the Tertiary period (65 mya). ... Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants (also angiosperms or Magnoliophyta) are one of the major groups of modern plants, comprising those that produce seeds in specialized reproductive organs called flowers, where the ovulary or carpel is enclosed. ... Orders See text The Actinopterygii are the ray-finned fish. ... This article is about the marine animal. ... Extinct Orders Aulacocerida Phragmoteuthida Belemnitida Diplobelida Belemnoteuthina Belemnites (or belemnoids) are an extinct group of marine cephalopod, very similar in many ways to the modern squid and closely related to the modern cuttlefish. ... Slate pencil urchin (cidaroid) Group of black, long-spined Caribbean sea urchins, Diadema antillarum (Philippi) Sea urchin roe. ... The sponge, in the phylum Porifera, is a very primitive and specialized animal. ... Orders Saurischia    Sauropodomorpha    Theropoda Ornithischia Dinosaurs are animals that dominated the terrestrial ecosystem for over 100 million years. ... Genera Albertosaurus Daspletosaurus Gorgosaurus Tarbosaurus Tyrannosaurus The tyrannosaurids were a family of dinosaurs whose name is derived from the Greek words trannos, meaning tyrant; and sauros, meaning lizard. ... Genera Aegyptosaurus Andesaurus Antarctosaurus Argentinosaurus Argyrosaurus Bruhathkayosaurus Paralititan Saltasaurus Titanosaurus A titanosaurid (or more informally, a titanosaur) is a member of the family Titanosauridae, which is composed of sauropod dinosaurs such as the Saltasaurus and the Titanosaurus. ... Genera Lambeosaurinae     Corythosaurus    Lambeosaurus    Parasaurolophus Hadrosaurinae    Anasazisaurus     Anatotitan     Edmontosaurus     Hadrosaurus    Maiasaura    Prosaurolophus    Saurolophus    Shantungosaurus Hadrosaurids or duck-billed dinosaurs are members of the family Hadrosauridae, and include ornithopods such as Edmontosaurus and Parasaurolophus. ... Genera Centrosaurinae    Achelousaurus    Centrosaurus    Einiosaurus    Styracosaurus    Pachyrhinosaurus Ceratopsinae    Chasmosaurus    Diceratops    Pentaceratops    Protoceratops    Torosaurus    Triceratops Ceratopsids, or members of the Ceratopsidae, are a diverse group of marginocephalian dinosaurs like Triceratops and Styracosaurus. ... Subfamilies Mosasaurinae Plioplatecarpinae Tylosaurinae A mosasaur was not a dinosaur, but rather an ocean-dwelling serpentine marine reptile more closely related to snakes than to monitor lizards (Lee 1997). ... For other meanings of bird, see bird (disambiguation). ... Families Kollikodontidae (extinct) Ornithorhynchidae - Platypus Tachyglossidae - Echidnas Steropodontidae (extinct) Monotremes are mammals that are best known for laying eggs, instead of giving birth to live young like marsupials and placental mammals (Eutheria). ... Orders Superorder Ameridelphia Didelphimorphia Paucituberculata Superorder Australidelphia Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Marsupials are mammals in which the female typically has a pouch (called the marsupium, from which the name Marsupial derives) in which it rears its young through early infancy. ... Orders Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia Xenarthra Dermoptera: Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Placentalia and Eutheria are terms used to describe major groupings within the animal class of Mammalia. ... Pangea broke into the two supercontinents, Laurasia and Gondwana The southern supercontinent Gondwana (originally Gondwanaland) included most of the landmasses which make up todays continents of the southern hemisphere, including Antarctica, South America, Africa, Madagascar, India, Arabia, Australia-New Guinea and New Zealand. ... The Early Cretaceous - also called the Lower Cretaceous by geologists, is the earlier of the two major divisions of the Cretaceous period. ... The Jurassic period is a major unit of the geologic timescale that extends from about 200 million years BP at the end of the Triassic to 146 million years BP at the beginning of the Cretaceous. ... Upper Jurassic (also known as Malm) was an epoch of the Jurassic geologic period. ... Orders & Families Cordaitales † Pinales   Pinaceae - Pine family   Araucariaceae - Araucaria family   Podocarpaceae - Yellow-wood family   Sciadopityaceae - Umbrella-pine family   Cupressaceae - Cypress family   Cephalotaxaceae - Plum-yew family   Taxaceae - Yew family Vojnovskyales † Voltziales † The conifers, division Pinophyta, are one of 13 or 14 division level taxa within the Kingdom Plantae. ... Bennettitales is an order of plants in the anthophyte clade that first appeared in the Triassic period and became extinct toward the end of the Cretaceous. ... Families Cycadaceae cycas family Stangeriaceae stangeria family Zamiaceae zamia family Cycads are an ancient group of seed plants characterized by a large crown of compound leaves and a stout trunk. ... Classes Marattiopsida Osmundopsida Gleicheniopsida Pteridopsida A fern, or pteridophyte, is any one of a group of some twenty thousand species of plants classified in the Division Pteridophyta, formerly known as Filicophyta. ... Orders Saurischia    Sauropodomorpha    Theropoda Ornithischia Dinosaurs are animals that dominated the terrestrial ecosystem for over 100 million years. ... Families Brachiosauridae Camarasauridae Cetiosauridae Diplodocidae Euhelopodidae Nemegtosauridae Titanosauridae Vulcanodontidae Sauropoda, the sauropods, are a suborder or infraorder of the saurischian (lizard-hipped) dinosaurs. ... Families Allosauridae    Allosaurinae    ?Carcharodontosaurinae Sinraptoridae Carnosauria is a sub-group of Theropods, a group of predatory dinosaurs. ... Species (type) Stegosaurus was a large herbivorous dinosaur genus from the Upper Jurassic of North America. ... Orders Many - see section below. ... Suborders Amphisbaenia - Worm lizards Sauria- Lizards Serpentes - Snakes Squamata (scaled reptiles) is the largest recent order of reptiles, including lizards and snakes. ... Groups Cymbospondylus Mixosauridae Merriamosauria Shastasauridae/Shastasauria Euichthyosauria Parvipelvia Leptonectidae Thunnosauria Stenopterygidae Ichthyosauridae Ichthyosaurs (Greek for fish lizards) were giant marine reptiles that resemble a dolphin with teeth (see convergent evolution). ... Families Cryptoclididae Elasmosauridae Plesiosauridae Pliosauridae Plesiosaurs (PLEE-see-oh-SORES) were large, carnivorous aquatic reptiles. ... Orders Subclass Protobranchia Solemyoida Nuculoida Subclass Pteriomorphia - oysters Arcoida Mytiloida Pterioida Subclass Paleoheterodonta - mussels Trigoinoida Unionoida Subclass Heterodonta - clams, zebra mussels Veneroida Myoida Subclass Anomalosdesmata Pholadomyoida Animals of the Class Bivalvia are known as bivalves because they typically have two-part shells, with both parts being more or less symmetrical. ... This article is about the marine animal. ... Extinct Orders Aulacocerida Phragmoteuthida Belemnitida Diplobelida Belemnoteuthina Belemnites (or belemnoids) are an extinct group of marine cephalopod, very similar in many ways to the modern squid and closely related to the modern cuttlefish. ... Slate pencil urchin (cidaroid) Group of black, long-spined Caribbean sea urchins, Diadema antillarum (Philippi) Sea urchin roe. ... Orders Articulata Cladida (extinct) Flexibilia (extinct) Camerada (extinct) Disparida (extinct) Crinoids, also known as sea lilies or feather-stars, are marine animals that make up the class Crinoidea of the echinoderms (phylum Echinodermata). ... The sponge, in the phylum Porifera, is a very primitive and specialized animal. ... color=pink|name=Brachiopods [[Taxobox_image|image= |caption=Fossil brachiopods Onniella meeki. ... Map of Pangæa Pangaea (Greek for all lands) is the name Alfred Wegener used to refer to the supercontinent that existed during the Mesozoic era, before the process of plate tectonics separated the component continents. ... Pangea broke into the two supercontinents, Laurasia and Gondwana The southern supercontinent Gondwana (originally Gondwanaland) included most of the landmasses which make up todays continents of the southern hemisphere, including Antarctica, South America, Africa, Madagascar, India, Arabia, Australia-New Guinea and New Zealand. ... Laurasia was a supercontinent that broke off from the Pangaean supercontinent in the late Mesozoic era. ... The Middle Jurassic, called the Dogger in the European system of classification, is the second epoch of the Jurassic period. ... Lower Jurassic (also known as Lias) is the earliest of three epochs of Jurassic period. ... The Triassic is a geologic period that extends from about 245 to 202 million years ago (mya). ... Groups Crurotarsi     Crocodylia (crocodiles) Ornithodira     Pterosauria     Dinosauria        Aves (birds) Archosaurs (Greek for ruling reptiles) are a group of diapsid reptiles that first evolved from Archosauriform ancestors during the Olenekian (Lower Triassic). ... Cynodonta is the order that contains the most mammal-like of the non-mammalian therapsids, which are sometimes termed mammal-like reptiles. The most derived cynodonts are found within a taxon called Eucynodontia, which also contains the members of Mammalia. ... Orders Saurischia    Sauropodomorpha    Theropoda Ornithischia Dinosaurs are animals that dominated the terrestrial ecosystem for over 100 million years. ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals characterized by the presence of mammary glands... Suborders Rhamphorhynchoidea Pterodactyloidea Pterosaurs (TEH-row-sore, winged lizards) were flying reptiles of the clade Pterosauria. ... Subfamilies Family Crocodylidae    Crocodylinae    Alligatorinae    Gavialinae Crocodylia is an order of large reptiles that scientists believe branched off from class Reptilia about 220 million years ago. ... Groups Cymbospondylus Mixosauridae Merriamosauria Shastasauridae/Shastasauria Euichthyosauria Parvipelvia Leptonectidae Thunnosauria Stenopterygidae Ichthyosauridae Ichthyosaurs (Greek for fish lizards) were giant marine reptiles that resemble a dolphin with teeth (see convergent evolution). ... A placodont prehistoric reptile that lived like seals of today, catching food in water and spending some time on land. ... Orders See text The Actinopterygii are the ray-finned fish. ... The Paleozoic is a major division of the geologic timescale, one of four geologic eras. ... The Permian is a geologic period that extends from about 280 to 248 million years before the present (mya). ... Lopingian is the third of the three epoches of the Permian. ... Map of Pangæa Pangaea (Greek for all lands) is the name Alfred Wegener used to refer to the supercontinent that existed during the Mesozoic era, before the process of plate tectonics separated the component continents. ... Clades Caseasauria Eupelycosauria Edaphosauridae Sphenacodontia Sphenacodontidae Therapsida Synapsids (fused arch), formerly known as mammal-like reptiles, are a group of amniotes (the other being the sauropsids) that developed one hole in their skull (temporal fenestra) behind each eye, about 320 million years ago (Ma) during the late Carboniferous. ... It has been suggested that Prehistoric reptile be merged into this article or section. ... The pelycosaurs were smallish to large (upto 3 meters or more) primitive Late Paleozoic synapsid reptiles. ... Groups Biarmosuchia Dinocephalia Anomodontia Theriodontia    Cynodontia       (...mammals) Therapsids, previously known as the mammal-like reptiles, are a group of synapsids. ... For other uses, see Beetle (disambiguation). ... Suborders Archidiptera Eudiptera Brachycera Diptera are insects in which the hind wings are reduced to halteres. ... Orders Allogromiida Carterinida Fusulinida - extinct Globigerinida Involutinida Lagenida Miliolida Robertinida Rotaliida Silicolocunida Spirillinida Textulariida The Foraminifera, or forams for short, are a large group of amoeboid protists with reticulating pseudopods, fine strands that branch and merge to form a dynamic net. ... The Permian-Triassic extinction event, sometimes informally called the Great Dying, was an extinction event that occurred approximately 252 million years ago (mya), forming the boundary of the Permian and Triassic geologic periods. ... Guadalupian - the second of the three epoches of the Permian, it lasted from about 270 to 260 million years ago. ... Cisuralian is the first of the three epoches of the Permian. ... The Carboniferous is a major division of the geologic timescale that extends from the end of the Devonian period, about 340 million years ago (mya), to the beginning of the Permian period, about 280 mya. ... The Pennsylvanian is a geologic (sub)period lasting from roughly 325 million years before the present (BP) to 286 million years BP. As with most other geologic periods, the rock beds that define the period are well identified, but the exact date of the start and end are uncertain by... Classes & Orders Subclass: Apterygota Orders Archaeognatha (Bristletails) Thysanura (Silverfish) Monura - extinct Subclass: Pterygota Orders Ephemeroptera (mayflies) Odonata (dragonflies and damselflies) Diaphanopteroidea - extinct Palaeodictyoptera - extinct Megasecoptera - extinct Archodonata - extinct Infraclass: Neoptera Orders Blattodea (cockroaches) Isoptera (termites) Mantodea (mantids) Dermaptera (earwigs) Plecoptera (stoneflies) Orthoptera (grasshoppers, etc) Phasmatodea (walking sticks) Embioptera (webspinners) Zoraptera... Classes Synapsida Sauropsida Amphibia A tetrapod (Greek tetrapoda, four-legged) is a vertebrate animal having four feet, legs or leglike appendages. ... It has been suggested that Prehistoric reptile be merged into this article or section. ... Coal is a fossil fuel extracted from the ground either by underground mining, open-pit mining or strip mining. ... Fossil trunk of Lepidodendron aculeatum showing leaf scars Lepidodendron (also known as the Scale tree) is an extinct genus of primitive, vascular, arborescent (tree-like) plant related to the Lycopsids (club mosses). ... Species See text Calamites is a genus of extinct arborescent (tree-like) horsetails to which the modern horsetails (genus Equisetum) are closely related. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... This article is about the geologic period; for the North American culture, see Mississippian culture. ... The coniferous Coast Redwood, the tallest tree species on earth A tree can be defined as a large, perennial, woody plant. ... Classes Synapsida Sauropsida Amphibia A tetrapod (Greek tetrapoda, four-legged) is a vertebrate animal having four feet, legs or leglike appendages. ... Orders many, all extinct The eurypterids were the largest known arthropods that ever lived. ... Orders see text The Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nostrils, scales, two-chambered hearts, and skeletons made of cartilage. ... Classes Asteroidea Concentricycloidea Crinoidea Echinoidea Holothuroidea Ophiuroidea Echinoderms (Echinodermata) is a phylum of marine animals found in the ocean at all depths. ... Orders Articulata Cladida (extinct) Flexibilia (extinct) Camerada (extinct) Disparida (extinct) Crinoids, also known as sea lilies or feather-stars, are marine animals that make up the class Crinoidea of the echinoderms (phylum Echinodermata). ... Blastoids (Blastoidea) are an extinct type of stemmed echinoderm. ... Orders see Anthozoa Corals are gastrovascular marine cnidarians (phylum Cnidaria; class Anthozoa) existing as small sea anemone-like polyps, typically forming colonies of many individuals. ... Fossilized Bryozoa, Ordovician limestone, Batavia, Ohio Bryozoans (moss animals) are tiny colonial animals that generally build stony skeletons of calcium carbonate, superficially similar to coral. ... Families all extinct Goniatites are an extinct group of ammonite, which are related to the nautiloids. ... Orders Agnostida Redlichiida Corynexochida Lichida Phacopida Proetida Asaphida Harpetida Ptychopariida Proposed order Nektaspida Trilobites are extinct arthropods in the class Trilobita. ... Orders Nautilida Bactrida Nautiloids are a group of marine animals which all possess an external shell, the most well known example being the modern nautiluses. ... Glaciation, often called an ice age, is a geological phenomenon in which massive ice sheets form in the Arctic and Antarctic and advance toward the equator. ... Pangea broke into the two supercontinents, Laurasia and Gondwana The southern supercontinent Gondwana (originally Gondwanaland) included most of the landmasses which make up todays continents of the southern hemisphere, including Antarctica, South America, Africa, Madagascar, India, Arabia, Australia-New Guinea and New Zealand. ... The Devonian is a major division of the geologic timescale that extends from the end of the Silurian period (360 million years ago (mya)) to the beginning of the Mississippian subperiod of the Carboniferous (408. ... Families Lycopodiaceae Huperziaceae The Class Lycopodiopsida includes the clubmosses. ... Species Subgenus Equisetum Equisetum arvense - Field or Common Horsetail Equisetum bogotense - Andean Horsetail Equisetum diffusum - Himalayan Horsetail Equisetum fluviatile - Water Horsetail Equisetum palustre - Marsh Horsetail Equisetum pratense - Shade Horsetail Equisetum sylvaticum - Wood Horsetail Equisetum telmateia - Great Horsetail Subgenus Hippochaete Equisetum giganteum - Giant Horsetail Equisetum myriochaetum - Mexican Giant Horsetail Equisetum hyemale... Archaeopteris is an extinct genus of tree-like ferns that many scientists believe to be the first tree. ... color=pink|name=Brachiopods [[Taxobox_image|image= |caption=Fossil brachiopods Onniella meeki. ... Also called tetracoralla, the Rugosa are an extinct group of corals that were abundant in Middle Ordovician to Late Permian seas. ... Orders Articulata Cladida (extinct) Flexibilia (extinct) Camerada (extinct) Disparida (extinct) Crinoids, also known as sea lilies or feather-stars, are marine animals that make up the class Crinoidea of the echinoderms (phylum Echinodermata). ... Families all extinct Goniatites are an extinct group of ammonite, which are related to the nautiloids. ... This article is about the marine animal. ... Orders Sepiida Sepiolida Spirulida Teuthida Octopoda Vampyromorphida Subclass Coleoidea is the grouping of cephalopods containing all the primarily soft_bodied creatures. ... Orders Antiarchi † Arthrodira † Petalichthyda † Phyllolepida † Ptyctodontida † Rhenanida † The Placodermi are fish known from fossils dating to the Devonian period. ... Subclasses Coelacanthimorpha - Coelacanths Dipnoi - Lungfishes Tetrapoda Sarcopterygii is traditionally the class of lobe-finned fishes, consisting of lungfish and coelacanths. ... Subclasses Actinopterygii Sarcopterygii Osteichthyes are the bony fish, a group paraphyletic to the land vertebrates, which are sometimes included. ... Orders see text The Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nostrils, scales, two-chambered hearts, and skeletons made of cartilage. ... Classes Synapsida Sauropsida Amphibia A tetrapod (Greek tetrapoda, four-legged) is a vertebrate animal having four feet, legs or leglike appendages. ... Euramerica (also known as Laurussia) was a minor supercontinent created in the Devonian by the collision of Laurentia and Baltica. ... The Silurian is a major division of the geologic timescale that extends from the end of the Ordovician period, about 439 million years ago (mega years ago, mya), to the beginning of the Devonian period, about 408. ... Divisions Land plants (embryophytes) Non-vascular plants (bryophytes) Hepatophyta - liverworts Anthocerophyta - hornworts Bryophyta - mosses Vascular plants (tracheophytes) Lycopodiophyta - clubmosses Equisetophyta - horsetails Pteridophyta - true ferns Psilotophyta - whisk ferns Ophioglossophyta - adderstongues Seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta - flowering plants Adiantum pedatum (a fern... This page is about the creature known as the millipede. ... The largest terrestrial arthropods to ever walk the Earth, Arthropleurida resembled long cockroaches living in swamps. ... Groups Conodonta Hyperoartia Petromyzontidae (lampreys) Pteraspidomorphi (early jawless fish) Thelodonti Anaspida Cephalaspidomorphi (early jawless fish) Galeaspida Pituriaspida Osteostraci Gnathostomata (jawed vertebrates) Placodermi Chondrichthyes (cartilaginous fish) Acanthodii Osteichthyes (bony fish) Actinopterygii (ray-finned fish) Sarcopterygii (lobe-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) A fish is a poikilothermic (cold-blooded)* water-dwelling... Orders Agnatha (Greek, no jaws) is a Super-class of jawless fish in the phylum Chordata, Sub-Phylum Vertebrata. ... Orders many, all extinct The eurypterids were the largest known arthropods that ever lived. ... Also called tetracoralla, the Rugosa are an extinct group of corals that were abundant in Middle Ordovician to Late Permian seas. ... color=pink|name=Brachiopods [[Taxobox_image|image= |caption=Fossil brachiopods Onniella meeki. ... Orders Articulata Cladida (extinct) Flexibilia (extinct) Camerada (extinct) Disparida (extinct) Crinoids, also known as sea lilies or feather-stars, are marine animals that make up the class Crinoidea of the echinoderms (phylum Echinodermata). ... Orders Agnostida Redlichiida Corynexochida Lichida Phacopida Proetida Asaphida Harpetida Ptychopariida Proposed order Nektaspida Trilobites are extinct arthropods in the class Trilobita. ... Classes Caudofoveata Aplacophora Polyplacophora - Chitons Monoplacophora Bivalvia - Bivalves Scaphopoda - Tusk shells Gastropoda - Snails and Slugs Cephalopoda - Squids, Octopuses, etc. ... Graptolites (Graptolita) are colonial animals known chiefly from the Upper Cambrian through the Mississippian (Lower Carboniferous). ... The Ordovician period is the second of the six (seven in North America) periods of the Paleozoic era. ... The Late Ordovician, also called the Upper Ordovician by geologists, is the third subdivision of the Ordovician period At this time Western and Central Europe and North America collided to form Laurentia, while glaciers built up in Gondwana, which was positioned over the pole. ... Invertebrate is a term coined by Jean-Baptiste Lamarck to describe any animal without a spinal column. ... color=pink|name=Brachiopods [[Taxobox_image|image= |caption=Fossil brachiopods Onniella meeki. ... Orders Subclass Protobranchia Solemyoida Nuculoida Subclass Pteriomorphia - oysters Arcoida Mytiloida Pterioida Subclass Paleoheterodonta - mussels Trigoinoida Unionoida Subclass Heterodonta - clams, zebra mussels Veneroida Myoida Subclass Anomalosdesmata Pholadomyoida Animals of the Class Bivalvia are known as bivalves because they typically have two-part shells, with both parts being more or less symmetrical. ... Orders Nautilida Bactrida Nautiloids are a group of marine animals which all possess an external shell, the most well known example being the modern nautiluses. ... Orders Agnostida Redlichiida Corynexochida Lichida Phacopida Proetida Asaphida Harpetida Ptychopariida Proposed order Nektaspida Trilobites are extinct arthropods in the class Trilobita. ... Orders Archaeocopida (extinct) Leperditicopida (extinct) Palaeocopida (extinct) Podocopida Platycopida Myodocopida Introduction Ostracoda is a class of the Crustacea, sometimes known as the seed shrimp because of their appearance. ... Fossilized Bryozoa, Ordovician limestone, Batavia, Ohio Bryozoans (moss animals) are tiny colonial animals that generally build stony skeletons of calcium carbonate, superficially similar to coral. ... Classes Asteroidea Concentricycloidea Crinoidea Echinoidea Holothuroidea Ophiuroidea Echinoderms (Echinodermata) is a phylum of marine animals found in the ocean at all depths. ... Orders Articulata Cladida (extinct) Flexibilia (extinct) Camerada (extinct) Disparida (extinct) Crinoids, also known as sea lilies or feather-stars, are marine animals that make up the class Crinoidea of the echinoderms (phylum Echinodermata). ... Graptolites (Graptolita) are colonial animals known chiefly from the Upper Cambrian through the Mississippian (Lower Carboniferous). ... Conodonts are extinct worm-like forms with distinctive conical or multi-denticulate teeth made of apatite (calcium phosphate). ... Divisions Land plants (embryophytes) Non-vascular plants (bryophytes) Hepatophyta - liverworts Anthocerophyta - hornworts Bryophyta - mosses Vascular plants (tracheophytes) Lycopodiophyta - clubmosses Equisetophyta - horsetails Pteridophyta - true ferns Psilotophyta - whisk ferns Ophioglossophyta - adderstongues Seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta - flowering plants Adiantum pedatum (a fern... The Middle Ordovician is the second subdivision of the Ordovician period. ... The Ordovician period is the second of the six (seven in North America) periods of the Paleozoic era. ... The Cambrian is a major division of the geologic timescale that begins about 542 million years before the present (BP) at the end of the Proterozoic eon and ended about 490 million years BP with the beginning of the Ordovician period. ... The Furongian is an geological epoch that is part of the Cambrian Era. ... The Cambrian Explosion is the seemingly sudden appearance of a number of new complex organisms between 543 and 530 million years ago (MYA). ... Phylum is one of the levels of scientific classification of organisms; see the Phylum (biology) article. ... The Archeocyatha, also called Archaeocyathids, were sessile, reef-building marine organisms that lived during the Lower Cambrian period (500-600 million years ago). ... Orders Agnostida Redlichiida Corynexochida Lichida Phacopida Proetida Asaphida Harpetida Ptychopariida Proposed order Nektaspida Trilobites are extinct arthropods in the class Trilobita. ... Priapulida (priapulid worms, or penis worms) are a phylum of marine worms with an extensible spiny proboscis. ... The sponge, in the phylum Porifera, is a very primitive and specialized animal. ... color=pink|name=Brachiopods [[Taxobox_image|image= |caption=Fossil brachiopods Onniella meeki. ... Typical classes Petromyzontidae (lampreys) Placodermi - extinct Chondrichthyes (cartilaginous fish) Acanthodii - extinct Actinopterygii (ray-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ... Subphyla and Classes Anomalocaridae - Anomalocarids, extinct     Genus Anomalocaris     Genus Laggania     Genus Parapeytoia Opabinidae - Extinct     Genus Opabinia Unclassified anomalocarid-like specimens     Genus Kerygmachela     Genus Pambdelurion Anomalocarids (meaning odd shrimp) are a group of very early marine animals known from fossils found in Cambrian deposits in China, North America, and Australia. ... The Middle Cambrian is an geological epoch that is part of the Cambrian Era. ... The Early Cambrian is an geological epoch that is part of the Cambrian Era. ... In geology, the Proterozoic is an eon prior to the first abundant complex life on earth. ... The Neoproterozoic is a period of time roughly from 1000 million years before the present to 544 million years before the present. ... The Ediacaran period is the last geological period of the Neoproterozoic Era, just before the Cambrian. ... Phyla Radiata Cnidaria Ctenophora - Comb jellies Bilateria Protostomia Acoelomorpha Platyhelminthes - Flatworms Nemertina - Ribbon worms Gastrotricha Gnathostomulida - Jawed worms Micrognathozoa Rotifera - Rotifers Acanthocephala Priapulida Kinorhyncha Loricifera Entoprocta Nematoda - Roundworms Nematomorpha - Horsehair worms Cycliophora Mollusca - Mollusks Sipuncula - Peanut worms Annelida - Segmented worms Tardigrada - Water bears Onychophora - Velvet worms Arthropoda - Insects, etc. ... Trace fossils are those details preserved in rocks that are indirect evidence of life. ... The sponge, in the phylum Porifera, is a very primitive and specialized animal. ... // Generalità Il Periodo Cryogeniano (dal Greco cryos ghiaccio e genesi, nascita) è il secondo periodo geologico dell Era Neoprotozoica seguito poi dal periodo Ediacarano. ... The Snowball Earth, also known as the Varangian glaciation, is an hypothesis that has been around for several decades but which has recently been reformulated by Paul F. Hoffman, Sturgis Hooper Professor of Geology at Harvard University. ... Depiction of Rodinia at time of initial breakup. ... The Tonian is a geologic time period that lasted from 1000 million years ago to 850 million years ago. ... Acritarchs are small organic structures found as fossils. ... The Mesoproterozoic era is a geologic period that occurred between 1600 and 900 million years ago. ... The Stenian (from Greek stenos, narrow) is the final geologic period in the Mesoproterozoic Era and lasted from 1200 million years ago to 1000 million years ago. ... Depiction of Rodinia at time of initial breakup. ... The Ectasian (from Greek ectsis, extension) is the second geologic period in the Mesoproterozoic Era and lasted from 1400 million years ago to 1200 million years ago. ... The Calymmian (from Greek calymma, cover) is the first geologic period in the Mesoproterozoic Era and lasted from 1600 million years ago to 1400 million years ago. ... The Paleoproterozoic is the first of the three sub-divisions of the Proterozoic occurring between 2500 to 1600 million years ago. ... The Statherian (from Greek statheros, stable, firm) is the final geologic period in the Paleoproterozoic Era and lasted from 1800 million years ago to 1600 million years ago. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista Eukaryotes (also spelled eucaryotes) are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... The Orosirian (from Greek orosira, mountain range) is the third geologic period in the Paleoproterozoic Era and lasted from 2050 million years ago to 1800 million years ago. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... Atmosphere may refer to: a celestial body atmosphere, e. ... From the GeoWhen Database: Rhyacian Period From 2300 +/- 0 To 2050 +/- 0 Ma Start Defined By: Fixed Date End Defined By: Fixed Date Start Based On: Gradstein, Ogg, Smith, et. ... The Siderian (from Greek sideros, iron) is the first geologic period in the Paleoproterozoic Era and lasted from 2500 million years ago to 2300 million years ago. ... The Archean is a geologic eon; it is a somewhat antiquated term for the time span between 2500 million years before the present and 3800 million years before the present. ... The Neoarchean is a geologic era within the Archaean. ... A craton is an old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years. ... Earth cutaway from core to exosphere. ... The Mesoarchean is a geologic era within the Archean, spanning 3. ... Pre-Cambrian stromatolites in the Siyeh Formation, Glacier National Park. ... The Paleoarchean is a geologic era within the Archaean. ... Phototrophs or photoautotrophs are photosynthetic algae, fungi, bacteria and cyanobacteria which build up carbon dioxide and water into organic cell materials using energy from sunlight. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria is also the fictional name of a warring nation under Benzino Napaloni as dictator, in the 1940 film The Great Dictator... In the geologic timescale, the Eoarchean or EA was an era that lasted from about 3800 MYA to 3600 MYA. It is the first part of the Archaean eon and the first part of the Precambrian eon. ... Prokaryotes (from Old Greek pro- before + karyon nut, referring to the cell nucleus, + suffix -otos, pl. ... The name Hadean refers to a geologic period: the time prior to 3800 million years ago (mya). ... Earth, also known as the Earth, Terra, and (mostly in the 19th century) Tellus, is the third planet outward from the Sun. ... Faunal stages are a subdivision of geologic time used primarily by paleontologists who study fossils rather than by geologists who study rock formations. ... Radiometric dating is a technique used to date materials based on a knowledge of the decay rates of naturally occurring isotopes, and the current abundances. ... The International Commission on Stratigraphy concerns itself with stratigraphy on a global scale. ... A Global Boundary Stratotype Section and Point, abbreviated GSSP, is an internationally agreed upon stratigraphic section which serves as the reference section for a particular boundary on the geologic timescale. ... The Cenozoic Era (sometimes still Caenozoic in the United Kingdom) is the most recent of the four Categories: Cenozoic ... The Quaternary Period is the geologic time period from the end of the Pliocene Epoch roughly 1. ... The Tertiary period is one of the major divisions of the geologic timescale, from the end of the Cretaceous period about 64 million years ago to the start of the Quaternary period about 1. ... Neogene Period: A unit of geologic time consisting of the Miocene and Pliocene Epochs. ... Palaeogene (alternatively Paleogene) period is a unit of geologic time that began 65 and ended 23 million years ago. ... This article is about the geologic period; for the North American culture, see Mississippian culture. ... The Pennsylvanian is a geologic (sub)period lasting from roughly 325 million years before the present (BP) to 286 million years BP. As with most other geologic periods, the rock beds that define the period are well identified, but the exact date of the start and end are uncertain by... In geology, the Proterozoic is an eon prior to the first abundant complex life on earth. ... The Archean is a geologic eon; it is a somewhat antiquated term for the time span between 2500 million years before the present and 3800 million years before the present. ... The name Hadean refers to a geologic period: the time prior to 3800 million years ago (mya). ... The Precambrian or Cryptozoic is the period of the geologic timescale from the formation of Earth (around 4500 million years before the present [BP]) to the evolution of abundant macroscopic hard-shelled fossils, which marked the beginning of the Cambrian, some 542 million years BP. Remarkably little is known about... The Precambrian or Cryptozoic is the period of the geologic timescale from the formation of Earth around 4500 million years before the present (BP) to the evolution of abundant macroscopic hard-shelled fossils, which marked the beginning of the Cambrian, some 542 million years BP. Remarkably little is known about... A Global Standard Stratigraphic Age, often abbreviated GSSA, is an internationally agreed upon chronological age used to define the boundaries between different periods or epochs on the geologic timescale. ... The name Hadean refers to a geologic period: the time prior to 3800 million years ago (mya). ... The name Hadean refers to a geologic period: the time prior to 3,800,000,000 years before the present -- 3,800MA. The geologist Preston Cloud coined the now somewhat outdated term in 1972, originally to label the period before the earliest known rocks. ...

Graphical timeline



Millions of Years

References

See also

The age of the Earth is estimated to be 4. ... Precambrian (3. ... This timeline outlines the major events in the development of life on planet Earth. ... This timeline attempts to show the best scientific estimates of the timings of past events and predictions of the approximate timing of hypothetical future events with cosmological significance. ... The lunar geologic timescale divides the history of Earths Moon into six generally recognized geologic periods: Copernician Period : -1100 MY to present Eratosthenian Period : -3200 MY to -1100 MY Upper Imbrian Epoch : -3800 MY to -3200 MY Lower Imbrian Epoch : -3850 MY to -3800 MY Nectarian Epoch : -3920 MY... The Martian geologic timescale has three broad epochs defined by the number of impact craters on the surface; older surfaces have more craters. ... The term Anthropocene is used by some scientists to describe the most recent period in the Earths history, starting in the 18th century where the activities of the human race first began to have a significant global effect on the Earths climate and ecosystems. ... A logarithmic timeline, based on logarithmic scale, was developed by Heinz von Foerster, the philosopher and physicist. ...

External link


  Results from FactBites:
 
Geologic time scale - Wikipedia, the free encyclopedia (1711 words)
The geologic time scale is used by geologists and other scientists to describe the timing and relationships between events that have occurred during the history of the Earth.
The table of geologic periods presented here is in accordance with the dates and nomenclature proposed by the International Commission on Stratigraphy, and uses the standard color codes of the United States Geologic Survey.
Because geologic units occurring at the same time but from different parts of the world can often look different and contain different fossils, there are many examples where the same period of time was historically given different names in different locales.
  More results at FactBites »

 
 

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