document_title: Geologic time scale

question_text: he earth's geological time scale is divided into four main

question_tokens: he earth 's geological time scale is divided into four main

text: Geologic time scale

text: Terminology[edit]

text: The primary defined divisions of time are eons, in sequence the Hadean, the Archean, the Proterozoic and the Phanerozoic. The first three of these can be referred to collectively as the Precambrian supereon. Eons are divided into eras, which are in turn divided into periods, epochs and ages.

text: The following four timelines show the geologic time scale. The first shows the entire time from the formation of the Earth to the present, but this gives little space for the most recent eon. Therefore, the second timeline shows an expanded view of the most recent eon. In a similar way, the most recent era is expanded in the third timeline, and the most recent period is expanded in the fourth timeline.

text: Corresponding to eons, eras, periods, epochs and ages, the terms "eonothem", "erathem", "system", "series", "stage" are used to refer to the layers of rock that belong to these stretches of geologic time in Earth's history.

text: Geologists qualify these units as "early", "mid", and "late" when referring to time, and "lower", "middle", and "upper" when referring to the corresponding rocks. For example, the lower Jurassic Series in chronostratigraphy corresponds to the early Jurassic Epoch in geochronology.[2] The adjectives are capitalized when the subdivision is formally recognized, and lower case when not; thus "early Miocene" but "Early Jurassic."

text: Rationale[edit]

text: Evidence from radiometric dating indicates that Earth is about 4.54 billion years old.[3][4] The geology or deep time of Earth's past has been organized into various units according to events which took place. Different spans of time on the GTS are usually marked by corresponding changes in the composition of strata which indicate major geological or paleontological events, such as mass extinctions. For example, the boundary between the Cretaceous period and the Paleogene period is defined by the Cretaceous–Paleogene extinction event, which marked the demise of the non-avian dinosaurs and many other groups of life. Older time spans, which predate the reliable fossil record (before the Proterozoic eon), are defined by their absolute age.

text: Geologic units from the same time but different parts of the world often look different and contain different fossils, so the same time-span was historically given different names in different locales. For example, in North America, the Lower Cambrian is called the Waucoban series that is then subdivided into zones based on succession of trilobites. In East Asia and Siberia, the same unit is split into Alexian, Atdabanian, and Botomian stages. A key aspect of the work of the International Commission on Stratigraphy is to reconcile this conflicting terminology and define universal horizons that can be used around the world.[5]

text: Some other planets and moons in the Solar System have sufficiently rigid structures to have preserved records of their own histories, for example, Venus, Mars and the Earth's Moon. Dominantly fluid planets, such as the gas giants, do not preserve their history in a comparable manner. Apart from the Late Heavy Bombardment, events on other planets probably had little direct influence on the Earth, and events on Earth had correspondingly little effect on those planets. Construction of a time scale that links the planets is, therefore, of only limited relevance to the Earth's time scale, except in a Solar System context. The existence, timing, and terrestrial effects of the Late Heavy Bombardment is still debated.[a]

text: History and nomenclature of the time scale[edit]

text: Early history[edit]

text: In Ancient Greece, Aristotle (384-322 BCE) observed that fossils of seashells in rocks resembled those found on beaches – he inferred that the fossils in rocks were formed by living animals, and he reasoned that the positions of land and sea had changed over long periods of time. Leonardo da Vinci (1452–1519) concurred with Aristotle's interpretation that fossils represented the remains of ancient life.[6]

text: The 11th-century Persian geologist Avicenna (Ibn Sina, died 1037) and the 13th-century Dominican bishop Albertus Magnus (died 1280) extended Aristotle's explanation into a theory of a petrifying fluid.[7] Avicenna also first proposed one of the principles underlying geologic time scales, the law of superposition of strata, while discussing the origins of mountains in The Book of Healing (1027).[8][9] The Chinese naturalist Shen Kuo (1031–1095) also recognized the concept of "deep time".[10]

text: Establishment of primary principles[edit]

text: In the late 17th century Nicholas Steno (1638–1686) pronounced the principles underlying geologic (geological) time scales. Steno argued that rock layers (or strata) were laid down in succession, and that each represents a "slice" of time. He also formulated the law of superposition, which states that any given stratum is probably older than those above it and younger than those below it. While Steno's principles were simple, applying them proved challenging. Over the course of the 18th century geologists realized that:

text:
Sequences of strata often become eroded, distorted, tilted, or even inverted after deposition
Strata laid down at the same time in different areas could have entirely different appearances
The strata of any given area represented only part of Earth's long history

tag: ol

text: The Neptunist theories popular at this time (expounded by Abraham Werner (1749–1817) in the late 18th century) proposed that all rocks had precipitated out of a single enormous flood. A major shift in thinking came when James Hutton presented his Theory of the Earth; or, an Investigation of the Laws Observable in the Composition, Dissolution, and Restoration of Land Upon the Globe[11] before the Royal Society of Edinburgh in March and April 1785. It has been said[by whom?] that "as things appear from the perspective of the 20th century, James Hutton in those readings became the founder of modern geology".[12]:95-100 Hutton proposed that the interior of Earth was hot, and that this heat was the engine which drove the creation of new rock: land was eroded by air and water and deposited as layers in the sea; heat then consolidated the sediment into stone, and uplifted it into new lands. This theory, known as "Plutonism", stood in contrast to the "Neptunist" flood-oriented theory.

text: Formulation of geologic time scale[edit]

text: The first serious attempts to formulate a geologic time scale that could be applied anywhere on Earth were made in the late 18th century. The most influential of those early attempts (championed by Werner, among others) divided the rocks of 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" (now Paleogene and Neogene) remained in use as the name of a geological period well into the 20th century and "Quaternary" remains in formal use as the name of the current period.

text: The identification of strata by the fossils they contained, pioneered by William Smith, Georges Cuvier, Jean d'Omalius d'Halloy, and Alexandre Brogniart in the early 19th century, enabled geologists to divide Earth history more precisely. It also enabled them to correlate 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 between 1820 and 1850 of the strata and fossils of Europe produced the sequence of geological periods still used today.

text: Naming of geologic periods, eras and epochs[edit]

text: Early work on developing the geologic time scale was dominated by British geologists, and the names of the geologic periods reflect that dominance. The "Cambrian", (the classical name for Wales) and the "Ordovician", and "Silurian", named after ancient Welsh tribes, were periods defined using stratigraphic sequences from Wales.[12]:113–114 The "Devonian" was named for the English county of Devon, and the name "Carboniferous" was an adaptation of "the Coal Measures", the old British geologists’ term for the same set of strata. The "Permian" was named after Perm, Russia, because it was defined using strata in that region by Scottish geologist Roderick Murchison. However, some periods were defined by geologists from other countries. The "Triassic" was named in 1834 by a German geologist Friedrich Von Alberti from the three distinct layers (Latin trias meaning triad)—red beds, capped by chalk, followed by black shales—that are found throughout Germany and Northwest Europe, called the ‘Trias’. The "Jurassic" was named by a French geologist Alexandre Brogniart for the extensive marine limestone exposures of the Jura Mountains. The "Cretaceous" (from Latin creta meaning ‘chalk’) as a separate period was first defined by Belgian geologist Jean d'Omalius d'Halloy in 1822, using strata in the Paris basin[13] and named for the extensive beds of chalk (calcium carbonate deposited by the shells of marine invertebrates) found in Western Europe.

text: British geologists were also responsible for the grouping of periods into eras and the subdivision of the Tertiary and Quaternary periods into epochs. In 1841 John Phillips published the first global geologic time scale based on the types of fossils found in each era. Phillips’ scale helped standardize the use of terms like Paleozoic ("old life") which he extended to cover a larger period than it had in previous usage, and Mesozoic ("middle life") which he invented.[14]

text: Dating of time scales[edit]

text: When William Smith and Sir Charles Lyell first recognized that rock strata represented successive time periods, time scales could be estimated only very imprecisely since estimates of rates of change were uncertain. While creationists had been proposing dates of around six or seven thousand years for the age of Earth based on the Bible, early geologists were suggesting millions of years for geologic periods, and some were even suggesting a virtually infinite age for Earth.[citation needed] Geologists and paleontologists constructed the geologic table based on the relative positions of different strata and fossils, and estimated the time scales based on studying rates of various kinds of weathering, erosion, sedimentation, and lithification. Until the discovery of radioactivity in 1896 and the development of its geological applications through radiometric dating during the first half of the 20th century, the ages of various rock strata and the age of Earth were the subject of considerable debate.

text: The first geologic time scale that included absolute dates was published in 1913 by the British geologist Arthur Holmes.[15] He greatly furthered the newly created discipline of geochronology and published the world-renowned book The Age of the Earth in which he estimated Earth's age to be at least 1.6 billion years.[16]

text: In 1977, the Global Commission on Stratigraphy (now the International Commission on Stratigraphy) began to define global references known as GSSP (Global Boundary Stratotype Sections and Points) for geologic periods and faunal stages. The commission's most recent work is described in the 2004 geologic time scale of Gradstein et al.[17] A UML model for how the timescale is structured, relating it to the GSSP, is also available.[18][19]

text: The Anthropocene[edit]

text: The term "Anthropocene" is used informally by popular culture and a growing number of scientists to describe the current epoch in which we are living. The term was coined by Paul Crutzen and Eugene Stoermer in 2000 to describe the current time, in which humans have had an enormous impact on the environment. It has evolved to describe an "epoch" starting some time in the past and on the whole defined by anthropogenic carbon emissions and production and consumption of plastic goods that are left in the ground.[20]

text: Critics of this term say that the term should not be used because it is difficult, if not nearly impossible, to define a specific time when humans started influencing the rock strata—defining the start of an epoch.[21] Others say that humans have not even started to leave their biggest impact on Earth, and therefore the Anthropocene has not even started yet. Whatever the case, the ICS has not officially approved the term, as of September 2015[update].[22]

text: Table of geologic time[edit]

text: The following table summarizes the major events and characteristics of the periods of time making up the geologic time scale. This table is arranged with the most recent geologic periods at the top, and the most ancient at the bottom. The height of each table entry does not correspond to the duration of each subdivision of time.

text: The content of the table is based on the current official geologic time scale of the International Commission on Stratigraphy,[1] with the epoch names altered to the early/late format from lower/upper as recommended by the ICS when dealing with chronostratigraphy.[2]

text: A service providing a Resource Description Framework/Web Ontology Language representation of the timescale is available through the Commission for the Management and Application of Geoscience Information GeoSciML project as a service[23] and at a SPARQL end-point.[24][25]

text:
[hide]Supereon
Eon
Era
Period[b]
Epoch
Age[c]
Major events
Start, million years ago[c]

n/a[d]
Phanerozoic
Cenozoic[e]
Quaternary
Holocene

chrons: Subatlantic · Subboreal · Atlantic · Boreal · Preboreal

Quaternary Ice Age recedes, and the current interglacial begins. Sahara forms from savannah. Rise of human civilization, beginning of agriculture. Stone Age cultures give way to Bronze Age (3300 BC) and Iron Age (1200 BC), giving rise to many pre-historic cultures throughout the world. Little Ice Age (stadial) causes brief cooling in Northern Hemisphere from 1400 to 1850. Following the Industrial Revolution, atmospheric CO2 levels rise from around 280 parts per million volume (ppmv) to the current level of 400[28] ppmv.[29][f]
0.0117[g]

Pleistocene
Late (locally Tarantian · Tyrrhenian · Eemian · Sangamonian)
Flourishing and then extinction of Pleistocene megafauna. Evolution of anatomically modern humans. Quaternary Ice Age continues with glaciations and interstadials (and the accompanying fluctuations from 100 to 300 ppmv in atmospheric CO2 levels[29][f]), further intensification of Icehouse Earth conditions, roughly 1.6 Ma. Last glacial maximum (30000 years ago), last glacial period (18000–15000 years ago). Dawn of human stone-age cultures, with increasing technical complexity relative to previous ice age cultures, such as engravings and clay statues (e.g. Venus of Lespugue), particularly in the Mediterranean and Europe. Lake Toba supervolcano erupts 75000 years before present, causing a volcanic winter that possibly pushes humanity to the brink of extinction. Pleistocene ends with Oldest Dryas, Older Dryas/Allerød and Younger Dryas climate events, with Younger Dryas forming the boundary with the Holocene.
0.126

Middle (formerly Ionian)
0.781

Calabrian
1.8*

Gelasian
2.58*

Neogene
Pliocene
Piacenzian
Intensification of present Icehouse conditions, present (Quaternary) ice age begins roughly 2.58 Ma; cool and dry climate. Australopithecines, many of the existing genera of mammals, and recent mollusks appear. Homo habilis appears.
3.6*

Zanclean
5.333*

Miocene
Messinian
Moderate Icehouse climate, punctuated by ice ages; Orogeny in Northern Hemisphere. Modern mammal and bird families become recognizable. Horses and mastodons diverse. Grasses become ubiquitous. First apes appear (for reference see the article: "Sahelanthropus tchadensis"). Kaikoura Orogeny forms Southern Alps in New Zealand, continues today. Orogeny of the Alps in Europe slows, but continues to this day. Carpathian orogeny forms Carpathian Mountains in Central and Eastern Europe. Hellenic orogeny in Greece and Aegean Sea slows, but continues to this day. Middle Miocene Disruption occurs. Widespread forests slowly draw in massive amounts of CO2, gradually lowering the level of atmospheric CO2 from 650 ppmv down to around 100 ppmv.[29][f]
7.246*

Tortonian
11.63*

Serravallian
13.82*

Langhian
15.97

Burdigalian
20.44

Aquitanian
23.03*

Paleogene
Oligocene
Chattian
Warm but cooling climate, moving towards Icehouse; Rapid evolution and diversification of fauna, especially mammals. Major evolution and dispersal of modern types of flowering plants
28.1

Rupelian
33.9*

Eocene
Priabonian
Moderate, cooling climate. 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 and formation of its ice cap; Azolla event triggers ice age, and the Icehouse Earth climate that would follow it to this day, from the settlement and decay of seafloor algae drawing in massive amounts of atmospheric carbon dioxide,[29][f] lowering it from 3800 ppmv down to 650 ppmv. End of Laramide and Sevier Orogenies of the Rocky Mountains in North America. Orogeny of the Alps in Europe begins. Hellenic Orogeny begins in Greece and Aegean Sea.
37.8

Bartonian
41.2

Lutetian
47.8*

Ypresian
56*

Paleocene
Thanetian
Climate tropical. Modern plants appear; Mammals diversify into a number of primitive lineages following the extinction of the dinosaurs. First large mammals (up to bear or small hippo size). Alpine orogeny in Europe and Asia begins. Indian Subcontinent collides with Asia 55 Ma, Himalayan Orogeny starts between 52 and 48 Ma.
59.2*

Selandian
61.6*

Danian
66*

Mesozoic
Cretaceous
Late
Maastrichtian
Flowering plants proliferate, along with new types of insects. More modern teleost fish begin to appear. Ammonoidea, belemnites, rudist bivalves, echinoids and sponges all common. Many new types of dinosaurs (e.g. Tyrannosaurs, Titanosaurs, duck bills, and horned dinosaurs) evolve on land, as do Eusuchia (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. Beginning of Laramide and Sevier Orogenies of the Rocky Mountains. atmospheric CO2 close to present-day levels.
72.1 ± 0.2*

Campanian
83.6 ± 0.2

Santonian
86.3 ± 0.5*

Coniacian
89.8 ± 0.3

Turonian
93.9*

Cenomanian
100.5*

Early
Albian
~113

Aptian
~125

Barremian
~129.4

Hauterivian
~132.9

Valanginian
~139.8

Berriasian
~145

Jurassic
Late
Tithonian
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. Sea urchins very common, along with crinoids, starfish, sponges, and terebratulid and rhynchonellid brachiopods. Breakup of Pangaea into Gondwana and Laurasia. Nevadan orogeny in North America. Rangitata and Cimmerian Orogenies taper off. Atmospheric CO2 levels 4–5 times the present day levels (1200–1500 ppmv, compared to today's 385 ppmv[29][f]).
152.1 ± 0.9

Kimmeridgian
157.3 ± 1.0

Oxfordian
163.5 ± 1.0

Middle
Callovian
166.1 ± 1.2

Bathonian
168.3 ± 1.3*

Bajocian
170.3 ± 1.4*

Aalenian
174.1 ± 1.0*

Early
Toarcian
182.7 ± 0.7*

Pliensbachian
190.8 ± 1.0*

Sinemurian
199.3 ± 0.3*

Hettangian
201.3 ± 0.2*

Triassic
Late
Rhaetian
Archosaurs dominant on land as dinosaurs, in the oceans as Ichthyosaurs and nothosaurs, and in the air as pterosaurs. Cynodonts become smaller and more mammal-like, while first mammals and crocodilia appear. Dicroidiumflora common on land. Many large aquatic temnospondyl amphibians. Ceratitic ammonoids extremely common. Modern corals and teleost fish appear, as do many modern insect clades. Andean Orogeny in South America. Cimmerian Orogeny in Asia. Rangitata Orogeny begins in New Zealand. Hunter-Bowen Orogeny in Northern Australia, Queensland and New South Wales ends, (c. 260–225 Ma)
~208.5

Norian
~227

Carnian
~237*

Middle
Ladinian
~242*

Anisian
247.2

Early
Olenekian
251.2

Induan
251.902 ± 0.06*

Paleozoic
Permian
Lopingian
Changhsingian
Landmasses unite into supercontinent Pangaea, creating the Appalachians. End of Permo-Carboniferous glaciation. Synapsid reptiles (pelycosaurs and therapsids) become plentiful, while parareptiles and temnospondyl amphibians remain common. In the mid-Permian, coal-age flora are replaced by cone-bearing gymnosperms (the first true seed plants) and by the first true mosses. Beetles and flies evolve. Marine life flourishes in warm shallow reefs; productid and spiriferid brachiopods, bivalves, forams, and ammonoids all abundant. Permian-Triassic extinction event occurs 251 Ma: 95% of life on Earth becomes extinct, including all trilobites, graptolites, and blastoids. Ouachita and Innuitian orogenies in North America. Uralian orogeny in Europe/Asia tapers off. Altaid orogeny in Asia. Hunter-Bowen Orogeny on Australian continent begins (c. 260–225 Ma), forming the MacDonnell Ranges.
254.14 ± 0.07*

Wuchiapingian
259.1 ± 0.4*

Guadalupian
Capitanian
265.1 ± 0.4*

Wordian
268.8 ± 0.5*

Roadian
272.95 ± 0.5*

Cisuralian
Kungurian
283.5 ± 0.6

Artinskian
290.1 ± 0.26

Sakmarian
295 ± 0.18

Asselian
298.9 ± 0.15*

Carbon-
iferous[h]
Pennsylvanian
Gzhelian
Winged insects radiate suddenly; some (esp. Protodonata and Palaeodictyoptera) are quite large. Amphibians common and diverse. First reptiles and coal forests (scale trees, ferns, club trees, giant horsetails, Cordaites, etc.). Highest-ever atmospheric oxygen levels. Goniatites, brachiopods, bryozoa, bivalves, and corals plentiful in the seas and oceans. Testate forams proliferate. Uralian orogeny in Europe and Asia. Variscan orogeny occurs towards middle and late Mississippian Periods.
303.7 ± 0.1

Kasimovian
307 ± 0.1

Moscovian
315.2 ± 0.2

Bashkirian
323.2 ± 0.4*

Mississippian
Serpukhovian
Large primitive trees, first land vertebrates, and amphibious sea-scorpions live amid coal-forming coastal swamps. Lobe-finned rhizodonts are dominant big fresh-water predators. In the oceans, early sharks are common and quite diverse; echinoderms (especially crinoids and blastoids) abundant. Corals, bryozoa, goniatites and brachiopods (Productida, Spiriferida, etc.) very common, but trilobites and nautiloids decline. Glaciation in East Gondwana. Tuhua Orogeny in New Zealand tapers off.
330.9 ± 0.2

Viséan
346.7 ± 0.4*

Tournaisian
358.9 ± 0.4*

Devonian
Late
Famennian
First clubmosses, horsetails and ferns appear, as do the first seed-bearing plants (progymnosperms), first trees (the progymnosperm Archaeopteris), and first (wingless) insects. Strophomenid and atrypid brachiopods, rugose and tabulate corals, and crinoids are all abundant in the oceans. Goniatite ammonoids are plentiful, while squid-like coleoids arise. Trilobites and armoured agnaths decline, while jawed fishes (placoderms, lobe-finned and ray-finned fish, and early sharks) rule the seas. First amphibians still aquatic. "Old Red Continent" of Euramerica. Beginning of Acadian Orogeny for Anti-Atlas Mountains of North Africa, and Appalachian Mountains of North America, also the Antler, Variscan, and Tuhua Orogeny in New Zealand.
372.2 ± 1.6*

Frasnian
382.7 ± 1.6*

Middle
Givetian
387.7 ± 0.8*

Eifelian
393.3 ± 1.2*

Early
Emsian
407.6 ± 2.6*

Pragian
410.8 ± 2.8*

Lochkovian
419.2 ± 3.2*

Silurian
Pridoli
First vascular plants (the rhyniophytes and their relatives), first millipedes and arthropleurids on land. First jawed fishes, as well as many armoured jawless fish, populate the seas. Sea-scorpions reach large size. Tabulate and rugose corals, brachiopods (Pentamerida, Rhynchonellida, etc.), and crinoids all abundant. Trilobites and mollusks diverse; graptolites not as varied. Beginning of Caledonian Orogeny for hills in England, Ireland, Wales, Scotland, and the Scandinavian Mountains. Also continued into Devonian period as the Acadian Orogeny, above. Taconic Orogeny tapers off. Lachlan Orogeny on Australian continent tapers off.
423 ± 2.3*

Ludlow
Ludfordian
425.6 ± 0.9*

Gorstian
427.4 ± 0.5*

Wenlock
Homerian
430.5 ± 0.7*

Sheinwoodian
433.4 ± 0.8*

Llandovery
Telychian
438.5 ± 1.1*

Aeronian
440.8 ± 1.2*

Rhuddanian
443.8 ± 1.5*

Ordovician
Late
Hirnantian
Invertebrates diversify into many new types (e.g., long straight-shelled cephalopods). Early corals, articulate brachiopods (Orthida, Strophomenida, etc.), bivalves, nautiloids, trilobites, ostracods, bryozoa, many types of echinoderms (crinoids, cystoids, starfish, etc.), branched graptolites, and other taxa all common. Conodonts (early planktonic vertebrates) appear. First green plants and fungi on land. Ice age at end of period.
445.2 ± 1.4*

Katian
453 ± 0.7*

Sandbian
458.4 ± 0.9*

Middle
Darriwilian
467.3 ± 1.1*

Dapingian
470 ± 1.4*

Early
Floian
(formerly Arenig)
477.7 ± 1.4*

Tremadocian
485.4 ± 1.9*

Cambrian
Furongian
Stage 10
Major diversification of life in the Cambrian Explosion. Numerous fossils; most modern animal phyla appear. First chordates appear, along with a number of extinct, problematic phyla. Reef-building Archaeocyatha abundant; then vanish. Trilobites, priapulid worms, sponges, inarticulate brachiopods (unhinged lampshells), and numerous other animals. Anomalocarids are giant predators, while many Ediacaran fauna die out. Prokaryotes, protists (e.g., forams), fungi and algae continue to present day. Gondwana emerges. Petermann Orogeny on the Australian continent tapers off (550–535 Ma). Ross Orogeny in Antarctica. Adelaide Geosyncline (Delamerian Orogeny), majority of orogenic activity from 514–500 Ma. Lachlan Orogeny on Australian continent, c. 540–440 Ma. Atmospheric CO2 content roughly 20–35 times present-day (Holocene) levels (6000 ppmv compared to today's 385 ppmv)[29][f]
~489.5

Jiangshanian
~494*

Paibian
~497*

Series 3
Guzhangian
~500.5*

Drumian
~504.5*

Stage 5
~509

Series 2
Stage 4
~514

Stage 3
~521

Terreneuvian
Stage 2
~529

Fortunian
~541 ± 1.0*

Precambrian[i]
Proterozoic[j]
Neoproterozoic[j]
Ediacaran
Good fossils of the first multi-celled animals. Ediacaran biota flourish worldwide in seas. Simple trace fossils of possible worm-like Trichophycus, etc. First sponges and trilobitomorphs. Enigmatic forms include many soft-jellied creatures shaped like bags, disks, or quilts (like Dickinsonia). Taconic Orogeny in North America. Aravalli Range orogeny in Indian Subcontinent. Beginning of Petermann Orogeny on Australian continent. Beardmore Orogeny in Antarctica, 633–620 Ma.
~635*

Cryogenian
Possible "Snowball Earth" period. Fossils still rare. Rodinia landmass begins to break up. Late Ruker / Nimrod Orogeny in Antarctica tapers off.
~720[k]

Tonian
Rodinia supercontinent persists. Sveconorwegian orogeny ends. Trace fossils of simple multi-celled eukaryotes. First radiation of dinoflagellate-like acritarchs. Grenville Orogeny tapers off in North America. Pan-African orogeny in Africa. Lake Ruker / Nimrod Orogeny in Antarctica, 1,000 ± 150 Ma. Edmundian Orogeny (c. 920 – 850 Ma), Gascoyne Complex, Western Australia. Adelaide Geosyncline laid down on Australian continent, beginning of Adelaide Geosyncline (Delamerian Orogeny) in Australia.
1000[k]

Mesoproterozoic[j]
Stenian
Narrow highly metamorphic belts due to orogeny as Rodinia forms. Sveconorwegian orogeny starts. Late Ruker / Nimrod Orogeny in Antarctica possibly begins. Musgrave Orogeny (c. 1,080 Ma), Musgrave Block, Central Australia.
1200[k]

Ectasian
Platform covers continue to expand. Green algae colonies in the seas. Grenville Orogeny in North America.
1400[k]

Calymmian
Platform covers expand. Barramundi Orogeny, McArthur Basin, Northern Australia, and Isan Orogeny, c.1,600 Ma, Mount Isa Block, Queensland
1600[k]

Paleoproterozoic[j]
Statherian
First complex single-celled life: protists with nuclei. Columbia is the primordial supercontinent. Kimban Orogeny in Australian continent ends. Yapungku Orogeny on Yilgarn craton, in Western Australia. Mangaroon Orogeny, 1,680–1,620 Ma, on the Gascoyne Complex in Western Australia. Kararan Orogeny (1,650 Ma), Gawler Craton, South Australia.
1800[k]

Orosirian
The atmosphere becomes oxygenic. Vredefort and Sudbury Basin asteroid impacts. Much orogeny. Penokean and Trans-Hudsonian Orogenies in North America. Early Ruker Orogeny in Antarctica, 2,000–1,700 Ma. Glenburgh Orogeny, Glenburgh Terrane, Australian continent c. 2,005–1,920 Ma. Kimban Orogeny, Gawler craton in Australian continent begins.
2050[k]

Rhyacian
Bushveld Igneous Complex forms. Huronian glaciation.
2300[k]

Siderian
Oxygen catastrophe: banded iron formations forms. Sleaford Orogeny on Australian continent, Gawler Craton 2,440–2,420 Ma.
2500[k]

Archean[j]
Neoarchean[j]
Stabilization of most modern cratons; possible mantle overturn event. Insell Orogeny, 2,650 ± 150 Ma. Abitibi greenstone belt in present-day Ontario and Quebec begins to form, stabilizes by 2,600 Ma.
2800[k]

Mesoarchean[j]
First stromatolites (probably colonial cyanobacteria). Oldest macrofossils. Humboldt Orogeny in Antarctica. Blake River Megacaldera Complex begins to form in present-day Ontario and Quebec, ends by roughly 2,696 Ma.
3200[k]

Paleoarchean[j]
First known oxygen-producing bacteria. Oldest definitive microfossils. Oldest cratons on Earth (such as the Canadian Shield and the Pilbara Craton) may have formed during this period.[l] Rayner Orogeny in Antarctica.
3600[k]

Eoarchean[j]
Simple single-celled life (probably bacteria and archaea). Oldest probable microfossils. The first life forms and self-replicating RNA molecules evolve around 4,000 Ma, after the Late Heavy Bombardment ends on Earth. Napier Orogeny in Antarctica, 4,000 ± 200 Ma.
~4000

Hadean[j][m]
Early Imbrian (Neohadean) (unofficial)[j][n]
Indirect photosynthetic evidence (e.g., kerogen) of primordial life. This era overlaps the beginning of the Late Heavy Bombardment of the Inner Solar System, produced possibly by the planetary migration of Neptune into the Kuiper belt as a result of orbital resonances between Jupiter and Saturn. Oldest known rock (4,031 to 3,580 Ma).[30]
4130[31]

Nectarian (Mesohadean) (unofficial)[j][n]
Possible first appearance of plate tectonics. This unit gets its name from the lunar geologic timescale when the Nectaris Basin and other greater lunar basins form by big impact events. Earliest evidence for life based on unusually high amounts of light isotopes of carbon, a common sign of life.
4280[31]

Basin Groups (Paleohadean) (unofficial)[j][n]
End of the Early Bombardment Phase. Oldest known mineral (Zircon, 4,404 ± 8 Ma). Asteroids and comets bring water to Earth.[32]
4533[31]

Cryptic (Eohadean) (unofficial)[j][n]
Formation of Moon (4,533 to 4,527 Ma), probably from giant impact, since the end of this era. Formation of Earth (4,570 to 4,567.17 Ma), Early Bombardment Phase begins. Formation of Sun (4,680 to 4,630 Ma) .
4600

text: Proposed Precambrian timeline[edit]

text: The ICS's Geologic Time Scale 2012 book which includes the new approved time scale also displays a proposal to substantially revise the Precambrian time scale to reflect important events such as the formation of the Earth or the Great Oxidation Event, among others, while at the same time maintaining most of the previous chronostratigraphic nomenclature for the pertinent time span.[33] (See also Period (geology)#Structure.)

text:
Hadean Eon – 4600–4031 MYA[contradictory]

Chaotian Era – 4600–4404 MYA – the name alluding both to the mythological Chaos and the chaotic phase of planet formation[33][34][35][contradictory]
Jack Hillsian or Zirconian Era – 4404–4031 MYA – both names allude to the Jack Hills Greenstone Belt which provided the oldest mineral grains on Earth, zircons[33][34]

Archean Eon – 4031–2420 MYA

Paleoarchean Era – 4031–3490 MYA

Acastan Period – 4031–3810 MYA – named after the Acasta Gneiss[33][34]
Isuan Period – 3810–3490 MYA – named after the Isua Greenstone Belt[33]

Mesoarchean Era – 3490–2780 MYA

Vaalbaran Period – 3490–3020 MYA – a portmanteau based on the names of the Kapvaal (Southern Africa) and Pilbara (Western Australia) cratons[33]
Pongolan Period – 3020–2780 MYA – named after the Pongola Supergroup[33]

Neoarchean Era – 2780–2420 MYA

Methanian Period – 2780–2630 MYA – named for the inferred predominance of methanotrophic prokaryotes[33]
Siderian Period – 2630–2420 MYA – named for the voluminous banded iron formations formed within its duration[33]

Proterozoic Eon – 2420–541 MYA

Paleoproterozoic Era – 2420–1780 MYA

Oxygenian Period – 2420–2250 MYA – named for displaying the first evidence for a global oxidizing atmosphere[33]
Jatulian or Eukaryian Period – 2250–2060 MYA – names are respectively for the Lomagundi–Jatuli δ13C isotopic excursion event spanning its duration, and for the (proposed)[36][37] first fossil appearance of eukaryotes[33]
Columbian Period – 2060–1780 MYA – named after the supercontinent Columbia[33]

Mesoproterozoic Era – 1780–850 MYA

Rodinian Period – 1780–850 MYA – named after the supercontinent Rodinia, stable environment[33]

Neoproterozoic Era – 850–541 MYA

Cryogenian Period – 850–630 MYA – named for the occurrence of several glaciations[33]
Ediacaran Period – 630–541 MYA

text: Shown to scale:

text: Compare with the current official timeline, not shown to scale:


document_title: States of Nigeria

question_text: when did nigeria become a federation of 19 states

root

text: States of Nigeria

text: Current states and the Federal Capital Territory[edit]

text:
A clickable map of Nigeria exhibiting its 36 states and the federal capital territory.

States

Abia
Adamawa
Akwa Ibom
Anambra
Bauchi
Bayelsa
Benue
Borno
Cross River
Delta
Ebonyi
Enugu

Edo
Ekiti
Gombe
Imo
Jigawa
Kaduna
Kano
Katsina
Kebbi
Kogi
Kwara
Lagos

Nasarawa
Niger
Ogun
Ondo
Osun
Oyo
Plateau
Rivers
Sokoto
Taraba
Yobe
Zamfara

Territory

Federal Capital Territory (FCT)

tag: table

text: Evolution of Nigerian states[edit]

text:
Date
Events
Map

1960-1963
At the time of independence in 1960, Nigeria was a Federal State of three Regions: Northern, Western, and Eastern. Additionally, provinces, which were a legacy of colonial times, remained extant until they were abolished in 1976.

1963-1967
In 1963, two provinces were detached from the Western Region to form the new Mid-Western Region.

1967-1976
In 1967, the regions were replaced by 12 states due to a military decree; only the former Mid-Western Region escaped division, and formed a single state following the restructuring. From 1967 to 1970 the areas of Mid-Western State and the Eastern Region attempted to secede, as a nation called Biafra during the Nigerian civil war.

1976-1987
In 1976, seven new states were created, making 19 altogether.[2]

1987-1991
During this period, there were 21 states and later, Abuja, the Federal Capital Territory.

1991-1996
During this period, there were 30 states and the Federal Capital Territory. The Federal Capital Territory was established in 1991. In 1987 two new states were established, followed by another nine in 1991, bringing the total to 30. The latest change, in 1996, resulted in the present number of 36 states.

text: Government[edit]

text: As sovereign entities, States of Nigeria have the right to organize/structure their individual governments in any way within the parameters set by the Constitution of Nigeria.

tag: p

text: Legislature[edit]

text: At the State level the legislature is unicameral with the number of its members equal to three times the amount of legislatures it has in the Federal House of Representatives, it has the power to legislate on matters on the concurrent list.

text: Executive[edit]

text: At the State level the Head of the executive is called the Governor who has the power to appoint people to the State Executive Council subject to the advice and consent of the State House of Assembly (Legislature). The Head of a ministry at the State level is called commissioner who is assisted by a permanent secretary who is also a senior civil servant of the State.

text: Judiciary[edit]

text: The Judiciary is one of the co-equal arms of the State government concerned with the interpretation of the laws of the State government. The Judiciary is headed by the Chief justice of the State appointed by the governor subject to the approval of the State House of Assembly.

text: Chronology[edit]

text:
Regions
States

1960
1963
1967
1976
1987
1991
1996

Eastern
South-Eastern
Cross-River
Akwa Ibom

Cross-River

East Central
Imo
Imo

Abia
Abia

Ebonyi

Anambra
Enugu

Enugu

Anambra

Rivers
Bayelsa

Rivers

Western
Mid-Western
Bendel
Delta

Edo

Western
Lagos

Western
Ogun

Ondo
Ekiti

Ondo

Oyo
Osun

Oyo

Northern
Benue-Plateau
Plateau
Nasarawa

Plateau

Benue
Benue

Kogi

Kwara

Kwara

Kano
Jigawa

Kano

North Central
Kaduna
Kaduna

Katsina

North Western
Niger

Sokoto
Kebbi

Sokoto
Sokoto

Zamfara

North Eastern
Bauchi
Bauchi

Gombe

Borno
Borno

Yobe

Gongola
Adamawa

Taraba


document_title: Richmond, Texas

question_text: how far is richmond tx from houston tx

question_tokens: how far is richmond tx from houston tx

text: Richmond, Texas

text: History[edit]

text: In 1822, a group of Austin's colonists went up the Brazos River, stopping near present-day Richmond where they built a fort called "Fort Bend". Named after Richmond, England, the town was among the 19 cities first incorporated by the short-lived Republic of Texas, in 1837. Early residents of the city include many prominent figures in Texas lore such as Jane Long, Deaf Smith, and Mirabeau Lamar, who are all buried in Richmond. On August 16, 1889, the town was the site of the "Battle of Richmond", an armed fight culminating the Jaybird–Woodpecker War, a violent feud over post-Reconstruction political control of Fort Bend County. The mayor from 1949 until his death in 2012 was Hilmar Moore.[5][6]

text: Historically Richmond had government agencies and nonprofit organizations, while most of the area private businesses were located in Rosenberg.[7]

text:
The Long-Smith Cottage was built around 1837 on Jane Long's property and later moved to its current site.

The John M. Moore Home was built in 1883 and remodeled in 1905. It is now a museum.

The  McNabb House was built by Phillip Vogel in the 1850s and bought by A. D. McNabb in the 1880s.

The McFarlane House belongs to the Fort Bend Museum.

tag: ul

text: Geography[edit]

text: Richmond is located near the center of Fort Bend County.  Most of the city is situated on the southwest side of the Brazos River, with a small portion (Richmond Landing) on the northeast side, connected by US Highway 90A. Richmond is bordered to the southwest by the city of Rosenberg. US 90A leads east 8 miles (13 km) to Sugar Land and west through Rosenberg 19 miles (31 km) to East Bernard. Downtown Houston is 30 miles (48 km) to the northeast.

text: According to the United States Census Bureau, the city of Richmond has a total area of 4.3 square miles (11.1 km2), of which 3.9 square miles (10.2 km2) are land and 0.35 square miles (0.9 km2), or 8.22%, is covered by  water.[4]

text: In 2003, Jeannie Kever of the Houston Chronicle said, "Some of the old buildings have been reincarnated as shops or law offices. But in other ways, life in Richmond isn't so different from that in the big city, with its Wal-Mart and fast-food joints, check-cashing businesses and strip-center sprawl."[7] As of  2006[update] several strip malls are along U.S. Route 59 south of town. During the same year, the community included tack stores, two-lane blacktop roads, and horse ranches. John P. Lopez of the Houston Chronicle said, "Richmond is a city of contradiction and transition. It's as if the place is not sure if it wants to be a part of Houston's bustle or remain a slow-paced farm and ranch town. It tries to be both," and, "It is part Acres Homes, part Fort Bend County Fair."[8]

text: Communities[edit]

text: The wealthiest neighborhood, as of 2003, in Richmond is Hillcrest. Winston Terrace, another neighborhood, had its first houses built in 1940. Construction increased around the end of World War II. Most of the houses were built between 1940 and 1965. Jeannie Kever of the Houston Chronicle said that Winston Terrace is "a swath of mid-20th-century America, with sweeping oak trees and colorful brick or wood bungalows, named for the descendants of one of the region's most illustrious pioneers."[7]

text: "Mud Alley" as of 1985 had older bars and strip clubs. Mud Alley is located in an area which, in 1985, housed most of the African Americans in Richmond.[9] As of 1993 many police raids for drugs occurred in "Mud Alley".[10] "Mud Alley" was known by several other nicknames, including "Little Boomtown". Historically, the area had a lot of recreational drugs.[8]

text: Climate[edit]

text:
hideClimate data for Richmond, TX

Month

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Year

Record high °F (°C)

84 (29)

89 (32)

92 (33)

95 (35)

99 (37)

102 (39)

105 (41)

105 (41)

108 (42)

98 (37)

91 (33)

90 (32)

108 (42)

Average high °F (°C)

65 (18)

68 (20)

74 (23)

81 (27)

88 (31)

93 (34)

95 (35)

96 (36)

91 (33)

84 (29)

75 (24)

67 (19)

81.4 (27.4)

Daily mean °F (°C)

55 (13)

58 (14)

64 (18)

71 (22)

79 (26)

84 (29)

86 (30)

87 (31)

81 (27)

74 (23)

65 (18)

56 (13)

71.7 (22.1)

Average low °F (°C)

44 (7)

48 (9)

53 (12)

61 (16)

69 (21)

75 (24)

77 (25)

77 (25)

71 (22)

63 (17)

54 (12)

45 (7)

61.4 (16.3)

Record low °F (°C)

6 (−14)

9 (−13)

21 (−6)

32 (0)

47 (8)

56 (13)

63 (17)

60 (16)

47 (8)

30 (−1)

22 (−6)

6 (−14)

6 (−14)

Average rainfall inches (mm)

3.55 (90.2)

3.18 (80.8)

3.43 (87.1)

3.36 (85.3)

4.30 (109.2)

5.65 (143.5)

3.97 (100.8)

4.43 (112.5)

5.10 (129.5)

5.28 (134.1)

4.84 (122.9)

3.37 (85.6)

50.46 (1,281.7)

Source: [11]

text: Demographics[edit]

text:
Historical population

Census
Pop.

%±
1870816—18801,15641.7%1890993−14.1%19101,371—19201,273−7.1%19301,43212.5%19402,02641.5%19502,0300.2%19603,66880.7%19705,77757.5%19809,69267.8%19909,8011.1%200011,08113.1%201011,6795.4%Est. 201612,092[12]3.5%U.S. Decennial Census[13]

text: As of the census[2] of 2000, there were 11,081 people, 3,413 households, and 2,628 families residing in the city.  The population density was 2,975.4 people per square mile (1,150.1/km2).  There were 3,595 housing units at an average density of 965.3 per square mile (373.1/km2).  The racial makeup of the city was 51.20% White, 10.55% African American, 0.63% Native American, 3.53% Asian, 0.07% Pacific Islander, 31.00% from other races, and 3.01% from two or more races. Hispanic or Latino of any race were 58.71% of the population.

text: There were 3,413 households out of which 39.6% had children under the age of 18 living with them, 53.6% were married couples living together, 16.4% had a female householder with no husband present, and 23.0% were non-families. 18.7% of all households were made up of individuals and 6.7% had someone living alone who was 65 years of age or older.  The average household size was 3.16 and the average family size was 3.60.

text: In the city, the population was spread out with 31.6% under the age of 18, 11.0% from 18 to 24, 28.5% from 25 to 44, 18.7% from 45 to 64, and 10.1% who were 65 years of age or older.  The median age was 30 years. For every 100 females, there were 98.1 males.  For every 100 females age 18 and over, there were 95.2 males.

text: The median income for a household in the city was $34,888, and the median income for a family was $35,801. Males had a median income of $27,457 versus $22,723 for females. The per capita income for the city was $15,195. About 17.0% of families and 20.0% of the population were below the poverty line, including 30.4% of those under age 18 and 12.9% of those age 65 or over.

text: Economy[edit]

text: The Texas Department of Criminal Justice operates the Jester State Prison Farm units, including the Jester I Unit, the Carol Vance Unit (formerly the Jester II Unit), the Jester III Unit, and the Jester IV Unit, in an unincorporated area 4 miles (6.4 km) east of Richmond.[14][15]

text: Arts and culture[edit]

text: Public libraries[edit]

text: Fort Bend County Libraries operates the George Memorial Library, the central library and the site of the administrative offices of the library system, located along Farm to Market Road 762.[16] Richmond also has the Fort Bend County Law Library.[17]

text: The Main Library moved from Rosenberg to its current location in Richmond in 1986. The George Foundation funded the 77,000 square feet (7,200 m2) library facility, designed by Ronald Wedemeyer Associates and built on 6 acres (2.4 ha) of land. When the library opened, it had unfinished areas to facilitate future expansion.[16] In December 1989 the Commissioners Court of Fort Bend County, in accordance with Texas Local Government code §323.021(a), ordered the construction of a law library.[17] The main library expansion and the 1991 installation of an automation system used funds from the 1989 bond election, and expansion occurred on 1995 and 2002. The 2002 expansion included the addition of two conference rooms.[16]

text: Government[edit]

text: The United States Postal Service Richmond Post Office is located at 5560 Farm to Market Road 1640.[18]

text: The city is governed by a mayor and two commissioners elected at large for two-year terms.  The commission sets policy and the day-to-day management is done by a city manager hired by the commission.[19]

text: Hilmar G. Moore served as mayor from 1949 until his death on December 4, 2012 and was believed to be the longest-serving mayor in the United States.[20][21]

text:
Richmond Police Department is in the old jail.

William B. Travis building belongs to the county.

US post office.

BNSF freight train heads west through Richmond

text: Education[edit]

text: The corporate city limits of Richmond is served by Lamar Consolidated Independent School District.

text: Elementary schools within the Richmond city limits include Jane Long,[22] Pink,[23] and Deaf Smith.[24]

text: Wessendorff Middle School, Lamar Junior High School, and Lamar Consolidated High School serve the Richmond city limits. The three schools are in Rosenberg.[25][26]

text: Various schools operated by LCISD and neighboring Fort Bend Independent School District bear Richmond addresses, but do not serve the city of Richmond. George Ranch High School, Foster High School, Reading Junior High School, and Briscoe Junior High in LCISD and Travis High School and Bush High School in the Fort Bend Independent School District (FBISD) bear "Richmond, Texas" addresses.

text:
Jane Long Elementary School

T. L. Pink Elementary School

Deaf Smith Elementary School

text: Infrastructure[edit]

text: Transportation[edit]

text: Fort Bend County Public Transportation provides local bus service in Richmond.[27]


document_title: Biological pigment

question_text: in general all photosynthetic structures of a plant body will be which color

text: Biological pigment

text: Biological pigments[edit]

text: See conjugated systems for electron bond chemistry that causes these molecules to have pigment.

text:
Heme/porphyrin-based: chlorophyll, bilirubin, hemocyanin, hemoglobin, myoglobin
Light-emitting: luciferin
Carotenoids:
Hematochromes (algal pigments, mixes of carotenoids and their derivates)
Carotenes: alpha and beta carotene, lycopene, rhodopsin
Xanthophylls: canthaxanthin, zeaxanthin, lutein
Proteinaceous: phytochrome, phycobiliproteins
Polyene enolates: a class of red pigments unique to parrots
Other: melanin, urochrome, flavonoids

text: Pigments in plants[edit]

text: The primary function of pigments in plants is photosynthesis, which uses the green pigment chlorophyll along with several red and yellow pigments that help to capture as much light energy as possible.

text: Other functions of pigments in plants include attracting insects to flowers to encourage pollination.

text: Plant pigments include a variety of different kinds of molecule, including porphyrins, carotenoids, anthocyanins and betalains. All biological pigments selectively absorb certain wavelengths of light while reflecting others.[3][4]

text: The principal pigments responsible are:

text:
Chlorophyll is the primary pigment in plants; it is a chlorin that absorbs yellow and blue wavelengths of light while reflecting green. It is the presence and relative abundance of chlorophyll that gives plants their green color. All land plants and green algae possess two forms of this pigment: chlorophyll a and chlorophyll b. Kelps, diatoms, and other photosynthetic heterokonts contain chlorophyll c instead of b, while red algae possess only chlorophyll a. All chlorophylls serve as the primary means plants use to intercept light in order to fuel photosynthesis.
Carotenoids are red, orange, or yellow tetraterpenoids. During the process of photosynthesis, they have functions in light-harvesting (as accessory pigments), in photoprotection (energy dissipation via non-photochemical quenching as well as singlet oxygen scavenging for prevention of photooxidative damage), and also serve as protein structural elements. In higher plants, they also serve as precursors to the plant hormone abscisic acid.

text:
Plants, in general, contain six ubiquitous carotenoids: neoxanthin, violaxanthin, antheraxanthin, zeaxanthin, lutein and β-carotene.[5] Lutein is a yellow pigment found in fruits and vegetables and is the most abundant carotenoid in plants. Lycopene is the red pigment responsible for the color of tomatoes. Other less common carotenoids in plants include lutein epoxide (in many woody species), lactucaxanthin (found in lettuce), and alpha carotene (found in carrots).[6]  In cyanobacteria, many other carotenoids exist such as canthaxanthin, myxoxanthophyll, synechoxanthin, and echinenone.  Algal phototrophs such as dinoflagellates use peridinin as a light harvesting pigment.
While carotenoids can be found complexed within chlorophyll-binding proteins such as the photosynthetic reaction centers and light-harvesting complexes, they also are found within dedicated carotenoid proteins such as the orange carotenoid protein of cyanobacteria.

text: Anthocyanins (literally "flower blue") are water-soluble flavonoid pigments that appear red to blue, according to pH. They occur in all tissues of higher plants, providing color in leaves, plant stem, roots, flowers, and fruits, though not always in sufficient quantities to be noticeable. Anthocyanins are most visible in the petals of flowers of many species.[4]

text: Betalains are red or yellow pigments. Like anthocyanins they are water-soluble, but unlike anthocyanins they are synthesized from tyrosine. This class of pigments is found only in the Caryophyllales (including cactus and amaranth), and never co-occur in plants with anthocyanins.[4] Betalains are responsible for the deep red color of beets.

text:
A particularly noticeable manifestation of pigmentation in plants is seen with autumn leaf color, a phenomenon that affects the normally green leaves of many deciduous trees and shrubs whereby they take on, during a few weeks in the autumn season, various shades of red, yellow, purple, and brown.[7]
Chlorophylls degrade into colorless tetrapyrroles known as nonfluorescent chlorophyll catabolites (NCCs).[8]
As the predominant chlorophylls degrade, the hidden pigments of yellow xanthophylls and orange beta-carotene are revealed. These pigments are present throughout the year, but the red pigments, the anthocyanins, are synthesized de novo once roughly half of chlorophyll has been degraded. The amino acids released from degradation of light harvesting complexes are stored all winter in the tree's roots, branches, stems, and trunk until next spring when they are recycled to re‑leaf the tree.

text: Pigments in animals[edit]

text: Pigmentation is used by many animals for protection, by means of camouflage, mimicry, or warning coloration. Some animals including fish, amphibians and cephalopods use pigmented chromatophores to provide camouflage that varies to match the background.

text: Pigmentation is used in signalling between animals, such as in courtship and reproductive behavior. For example, some cephalopods use their chromatophores to communicate.

text: The photopigment rhodopsin intercepts light as the first step in the perception of light.

text: Skin pigments such as melanin may protect tissues from sunburn by ultraviolet radiation.

text: However, some biological structures in animals, such as heme groups that help to carry oxygen in the blood, are colored as a result of their structure. Their color does not have a protective or signalling function.

text: Diseases and conditions[edit]

text: A variety of diseases and abnormal conditions that involve pigmentation are in humans and animals, either from absence of or loss of pigmentation or pigment cells, or from the excess production of pigment.

text:
Albinism is an inherited disorder characterized by total or partial loss of melanin. Humans and animals that suffer from albinism are called "albinistic" (the term "albino" is also sometimes used, but may be considered offensive when applied to people).
Lamellar ichthyosis, also called "fish scale disease", is an inherited condition in which one symptom is excess production of melanin. The skin is darker than normal, and is characterized by darkened, scaly, dry patches.
Melasma is a condition in which dark brown patches of pigment appear on the face, influenced by hormonal changes. When it occurs during a pregnancy, this condition is called the mask of pregnancy.
ocular pigmentation is an accumulation of pigment in the eye, and may be caused by latanoprost medication.[9]
Vitiligo is a condition in which there is a loss of pigment-producing cells called melanocytes in patches of skin.

text: Pigments in marine animals[edit]

text: Carotenoids and carotenoproteins[edit]

text: Carotenoids are the most common group of pigments found in nature.[10] Over 600 different kinds of carotenoids are found in animals, plants, and microorganisms.

text: Animals are incapable of making their own carotenoids and thus rely on plants for these pigments.  Carotenoproteins are especially common among marine animals. These complexes are responsible for the various colors (red, purple, blue, green, etc.) to these marine invertebrates for mating rituals and camouflage. There are two main types of carotenoproteins: Type A and Type B. Type A has carotenoids (chromogen) which are stoichiometrically associated with a simple protein (glycoprotein). The second type, Type B, has carotenoids which are associated with a lipo protein and is usually less stable. While Type A is commonly found in the surface (shells and skins) of marine invertebrates, Type B is usually in eggs, ovaries, and blood. The colors and characteristic absorption of these carotenoprotein complexes are based upon the chemical binding of the chromogen and the protein subunits.

text: For example, the blue carotenoprotein, linckiacyanin has about 100-200 carotenoid molecules per every complex.[11] In addition, the functions of these pigment-protein complexes also change their chemical structure as well. Carotenoproteins that are within the photosynthetic structure are more common, but complicated. Pigment-protein complexes that are outside of the photosynthetic system are less common, but have a simpler structure. For example, there are only two of these blue astaxanthin-proteins in the jellyfish, Velella velella, contains only about 100 carotenoids per complex.[citation needed]

text: A common carotenoid in animals is astaxanthin, which gives off a purple-blue and green pigment. Astaxanthin’s color is formed by creating complexes with proteins in a certain order. For example, the crustochrin has approximately 20 astaxanthin molecules bonded with protein. When the complexes interact by exciton-exciton interaction, it lowers the absorbance maximum, changing the different color pigments.

text: In lobsters, there are various types of astaxanthin-protein complexes present. The first one is crustacyanin (max 632 nm), a slate-blue pigment found in the lobster’s carapace. The second one is crustochrin (max 409), a yellow pigment which is found on the outer layer of the carapace. Lastly, the lipoglycoprotein and ovoverdin forms a bright green pigment that is usually present in the outer layers of the carapace and the lobster eggs.[12][13]

text: Tetrapyrroles[edit]

text: Tetrapyrroles are the next most common group of pigments.[citation needed] They have four pyrrole rings, each ring consisting of C4H4NH. The main role of the tetrapyrroles is their connection in the biological oxidation process. Tetrapyrroles have a major role in electron transport and act as a replacement for many enzymes. They also have a role in the pigmentation of the marine organism's tissues.

text: Melanin[edit]

text: Melanin[14] is a class of compounds that serves as a pigment with different structures responsible for dark, tan, yellowish / reddish pigments in marine animals. It is produced as the amino acid tyrosine is converted into melanin, which is found in the skin, hair, and eyes. Derived from aerobic oxidation of phenols, they are polymers.

text: There are several different types of melanins considering that they are an aggregate of smaller component molecules, such as nitrogen containing melanins. There are two classes of pigments: black and brown insoluble eumelanins, which are derived from aerobic oxidation of tyrosine in the presence of tyrosinase, and the alkali-soluble phaeomelanins which range from a yellow to red brown color, arising from the deviation of the eumelanin pathway through the intervention of cysteine and/or glutathione. Eumelanins are usually found in the skin and eyes. Several different melanins include melanoprotein (dark brown melanin that is stored in high concentrations in the ink sac of the cuttlefish Sepia Officianalis), echinoidea (found in sand dollars, and the hearts of sea urchins), holothuroidea (found in sea cucumbers), and ophiuroidea (found in brittle and snake stars). These melanins are possibly polymers which arise from the repeated coupling of simple bi-polyfunctional monomdric intermediates, or of high molecular weights. The compounds benzothiazole and tetrahydroisoquinoline ring systems act as UV-absorbing compounds. There are several different types of melanins considering that they are an aggregate of smaller component molecules, such as nitrogen containing melanins.

text: Bioluminescence[edit]

text: The only light source in the deep sea, marine animals give off visible light energy called bioluminescence,[15] a subset of chemiluminescence. This is the chemical reaction in which chemical energy is converted to light energy. It is estimated that 90% of deep-sea animals produce some sort of bioluminescence. Considering that a large proportion of the visible light spectrum is absorbed before reaching the deep sea, most of the emitted light from the sea-animals is blue and green. However, some species may emit a red and infrared light, and there has even been a genus that is found to emit yellow bioluminescence. The organ that is responsible for the emission of bioluminescence is known as photophores. This type is only present in squid and fish, and is used to illuminate their ventral surfaces, which disguise their silhouettes from predators. The uses of the photophores in the sea-animals differ, such as lenses for controlling intensity of color, and the intensity of the light produced. Squids have both photophores and chromatophores which controls both of these intensities. Another thing that is responsible for the emission of bioluminescence, which is evident in the bursts of light that jellyfish emit, start with a luciferin (a photogen) and ends with the light emitter (a photagogikon.) Luciferin, luciferase, salt, and oxygen react and combine to create a single unit called photo-proteins, which can produce light when reacted with another molecule such as Ca+. Jellyfish use this as a defense mechanism; when a smaller predator is attempting to devour a jellyfish, it will flash its lights, which would therefore lure a larger predator and chase the smaller predator away. It is also used as mating behavior.

text: In reef-building coral and sea anemones, they fluoresce; light is absorbed at one wavelength, and re-emitted at another. These pigments may act as natural sunscreens, aid in photosynthesis, serve as warning coloration, attract mates, warn rivals, or confuse predators.

text: Chromatophores[edit]

text: Chromatophores are color pigment changing cells that are directly stimulated by central motor neurons. They are primarily used for quick environmental adaptation for camouflaging. The process of changing the color pigment of their skin relies on a single highly developed chromatophore cell and many muscles, nerves, glail and sheath cells. Chromatophores contract and contain vesicles that stores three different liquid pigments. Each color is indicated by the three types of chromatophore cells: erythrophores, melanophores, and xanthophores. The first type is the erythrophores, which contains reddish pigments such as carotenoids and pteridines. The second type is the melanophores, which contains black and brown pigments such as the melanins. The third type is the xanthophores which contains yellow pigments in the forms of carotenoids. The various colors are made by the combination of the different layers of the chromatophores. These cells are usually located beneath the skin or scale the animals. There are two categories of colors generated by the cell – biochrome and schematochromes. Biochromes are colors chemically formed microscopic, natural pigments. Their chemical composition is created to take in some color of light and reflect the rest. In contrast, schematochromes (structural colors) are colors created by light reflections from a colorless surface and refractions by tissues. Schematochromes act like prisms, refracting and dispersing visible light to the surroundings, which will eventually reflect a specific combination of colors. These categories are determined by the movement of pigments within the chromatophores. The physiological color changes are short-term and fast, found in fishes, and are a result from an animal’s response to a change in the environment. In contrast, the morphological color changes are long-term changes, occurs in different stages of the animal, and are due the change of numbers of chromatophores. To change the color pigments, transparency, or opacity, the cells alter in form and size, and stretch or contract their outer covering.

text: Photo-protective pigments[edit]

text: Due to damage from UV-A and UV-B, marine animals have evolved to have compounds that absorb UV light and act as sunscreen. Mycosporine-like amino acids (MAAs) can absorb UV rays at 310-360 nm. Melanin is another well-known UV-protector. Carotenoids and photopigments both indirectly act as photo-protective pigments, as they quench oxygen free-radicals. They also supplement photosynthetic pigments that absorb light energy in the blue region.

text: Defensive role of pigments[edit]

text: It's known that animals use their color patterns to warn off predators, however it has been observed that a sponge pigment mimicked a chemical which involved the regulation of moulting of an amphipod that was known to prey on sponges. So whenever that amphipod eats the sponge, the chemical pigments prevents the moulting, and the amphipod eventually dies.

text: Environmental influence on color[edit]

text: Coloration in invertebrates varies based on the depth, water temperature, food source, currents, geographic location, light exposure, and sedimentation. For example, the amount of carotenoid a certain sea anemone decreases as we go deeper into the ocean. Thus, the marine life that resides on deeper waters is less brilliant than the organisms that live in well-lit areas due to the reduction of pigments. In the colonies of the colonial ascidian-cyanophyte symbiosis Trididemnum solidum, their colors are different depending on the light regime in which they live. The colonies that are exposed to full sunlight are heavily calcified, thicker, and are white. In contrast the colonies that live in shaded areas have more phycoerythrin (pigment that absorbs green) in comparison to phycocyanin (pigment that absorbs red), thinner, and are purple. The purple color in the shaded colonies are mainly due to the phycobilin pigment of the algae, meaning the variation of exposure in light changes the colors of these colonies.

text: Adaptive coloration[edit]

text: Aposematism is the warning coloration to signal potential predators to stay away. In many chromodrorid nudibranchs, they take in distasteful and toxic chemicals emitted from sponges and store them in their repugnatorial glands (located around the mantle edge). Predators of nudibranchs have learned to avoid these certain nudibranchs based on their bright color patterns. Preys also protect themselves by their toxic compounds ranging from a variety of organic and inorganic compounds.

text: Physiological activities[edit]

text: Pigments of marine animals serve several different purposes, other than defensive roles. Some pigments are known to protect against UV (see photo-protective pigments.) In the nudibranch Nembrotha Kubaryana, tetrapyrrole pigment 13 has been found to be a potent antimicrobial agent. Also in this creature, tamjamines A, B, C, E, and F has shown antimicrobial, antitumor, and immunosuppressive activities.

text: Sesquiterpenoids are recognized for their blue and purple colors, but it has also been reported to exhibit various bioactivities such as antibacterial, immunoregulating, antimicrobial, and cytotoxic, as well as the inhibitory activity against cell division in the fertilized sea urchin and ascidian eggs. Several other pigments have been shown to be cytotoxic. In fact, two new carotenoids that were isolated from a sponge called Phakellia stelliderma showed mild cytotoxicity against mouse leukemia cells. Other pigments with medical involvements include scytonemin, topsentins, and debromohymenialdisine have several lead compounds in the field of inflammation, rheumatoid arthritis and osteoarthritis respectively. There’s evidence that topsentins are potent mediators of immunogenic inflation, and topsentin and scytonemin are potent inhibitors of neurogenic inflammation.

text: Uses[edit]

text: Pigments may be extracted and used as dyes.

text: Pigments (such as astaxanthin and lycopene) are used as dietary supplements.