Devonian period 416 - 359. 2 million years ago ↓ PЄ Є O S D C P T J K PG N
Mean atmospheric O2 content over period duration	ca. The Precambrian ( Pre-Cambrian) is an informal name for the supereon comprising the eons of the Geologic timescale that came before the current The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with The Ordovician is a geologic period and system, the second of six of the Paleozoic era, and covers the time between 488 The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443 The Carboniferous is a geologic period and system that extends from the end of the Devonian period about 359 The Permian is a geologic period and system that extends from 299 The Triassic is a geologic period and system that extends from about 251 to 199 Ma (million years ago The Jurassic is a geologic period and system that extends from about Ma (million years ago to  Ma that is from the end of the Triassic to the beginning The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of The Paleogene (alternatively Palaeogene) is a geologic period and system that began 65 The Neogene is a geologic period and system starting 2303 ± 0 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the 15 Vol %[1] (75 % of modern level)
Mean atmospheric CO2 content over period duration	ca. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single 2200 ppm[2] (8 times pre-industrial level)
Mean surface temperature over period duration	ca. "Parts-per" notation is used especially in Science and Engineering, to denote Ratios (relative proportions in measured quantities particularly 20°C [3] (6°C above modern level)
Events of the Devonian period view • discuss • edit -420 — – -415 — – -410 — – -405 — – -400 — – -395 — – -390 — – -385 — – -380 — – -375 — – -370 — – -365 — – -360 — – -355 —     Silurian   Lochkovian Pragian Emsian Eifelian Givetian Frasnian Famennian   Carbon- iferous   ← Rhynie chert ← Hangenberg event ← Kellwasser event(s)[4] ← Widespread[5] shrubs & trees ← S. The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443 The Carboniferous is a geologic period and system that extends from the end of the Devonian period about 359 The Rhynie chert is an Early Devonian Lagerstätte found near the village of Rhynie, Aberdeenshire, Scotland, containing exceptionally The Late Devonian extinction was one of five major Extinction events in the history of the Earth's Biota. The Late Devonian extinction was one of five major Extinction events in the history of the Earth's Biota. America glaciation begins ← Hunsrück fauna D e v o n i a n  Palæozoic Key events of the Devonian period. The Hunsrück Slate (Hunsrückschiefer is a Devonian Lagerstätte famous for exceptional preservation of a highly diverse Fossil fauna assemblage The Paleozoic or Palaeozoic Era (from the Greek palaio (παλαιο "old" and zoe (ζωη "life" meaning "ancient life" Axis scale: millions of years ago.

The Devonian is a geologic period and system of the Paleozoic era spanning from 416 ±2. The Paleozoic or Palaeozoic Era (from the Greek palaio (παλαιο "old" and zoe (ζωη "life" meaning "ancient life" 8 to 359.2 ±2. 5 million years ago (ICS, 2004)^[6]. The International Commission on Stratigraphy (ICS, sometimes referred to by the unofficial " International Stratigraphic Commission " is a daughter or major Subcommittee It is named after Devon, England, where rocks from this period were first studied. Devon is a large county in the South West of England. The county is also referred to as Devonshire, but that is an entirely unofficial name England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland

During the Devonian Period, which occurred in the Paleozoic era, the first fish evolved legs^[7]and started to walk on land as tetrapods around 365 Ma. Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two A leg is a limb on an Animal 's Body that supports the rest of the animal above the ground between the Ankle and the Hip and is used for Tetrapods ( Greek τετραποδη tetrapoda, Latin Quadruped, "four-footed" are Vertebrate Animals Annum is one form of the Latin noun meaning Year, not a form normally used for derivatives in modern languages the accusative singular Various terrestrial arthropods also became well-established.

The first seed-bearing plants spread across dry land, forming huge forests. The spermatophytes (from the Greek word "Σπερματόφυτα" (also known as phanerogams) comprise those Plants that produce Seeds They are A forest is an area with a high density of Trees There are many definitions of a forest based on various criteria In the oceans, primitive sharks became more numerous than in the Silurian and the late Ordovician, and the first lobe-finned and bony fish. An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. Sharks ( Superorder Selachimorpha) are a type of Fish with a full cartilaginous Skeleton and a highly streamlined body The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443 The Late Ordovician, also called the Upper Ordovician by Geologists is the third epoch of the Ordovician period Sarcopterygii (from Greek σαρξ sarx, flesh and πτερυξ pteryx, fin is traditionally the class of lobe-finned Fishes consisting Osteichthyes (ˌɒstiːˈɪkθiːz also called bony fish, are a taxonomic Class of Fish that includes the ray-finned fish ( Actinopterygii The first ammonite mollusks appeared, and trilobites, the mollusc-like brachiopods, as well as great coral reefs were still common. Ammonites are an extinct group of marine animals of the subclass Ammonoidea in the class Cephalopoda phylum Molluscs are animals belonging to the phylum Mollusca. There are around 250000 extant Species within the phylum with an estimated 70000 Trilobites ("three-lobes" are extinct Arthropods that form the class Trilobita. Brachiopods (from Latin brachium, arm + New Latin -poda, foot are a small phylum of Benthic Invertebrates Also Coral reefs are Aragonite structures produced by living organisms found in marine waters with little to no nutrients in the water The Late Devonian extinction severely affected marine life. The Late Devonian extinction was one of five major Extinction events in the history of the Earth's Biota.

The paleogeography was dominated by the supercontinent of Gondwana to the south, the continent of Siberia to the north, and the early formation of the small supercontinent of Euramerica in the middle. Palaeogeography (sometimes spelled paleogeography) is the study of what the Geography was in times past In Geology, a supercontinent is a Landmass comprising more than one Continental core or Craton. Gondwana (ɡɒnˈdwɑːnə originally Gondwanaland) was a southern Supercontinent that existed about 500 to 200 Ma ago A continent is one of several large Landmasses on Earth. They are generally identified by Convention rather than any strict criteria with seven regions Siberia is the Craton located in the heart of the region of Siberia. Euramerica (also known as Laurussia or Old Red Continent) was a minor Supercontinent created in the Devonian as the result of a collision between

Naming

The Devonian period marks the beginning of extensive land colonization by plants. Plants are living Organisms belonging to the kingdom Plantae. With large herbivorous land-animals not yet being present, large forests could grow and shape the landscape. Herbivory is a form of Predation in which an Organism, known as a herbivore, consumes principally Autotrophs ref name=Campbell>Campbell

The period is named after Devon, a county in southwestern England, where Devonian outcrops are common. Devon is a large county in the South West of England. The county is also referred to as Devonshire, but that is an entirely unofficial name While the rock beds that define the start and end of the period are well identified, the exact dates are uncertain. In Geology and related fields a stratum (plural strata) is a layer of rock or Soil with internally consistent characteristics that distinguishes According to the International Commission on Stratigraphy (Ogg, 2004), the Devonian extends from the end of the Silurian Period 416. The International Commission on Stratigraphy (ICS, sometimes referred to by the unofficial " International Stratigraphic Commission " is a daughter or major Subcommittee The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443 0 ± 2. 8 million years ago (Mya), to the beginning of the Carboniferous Period 359. Annum is one form of the Latin noun meaning Year, not a form normally used for derivatives in modern languages the accusative singular The Carboniferous is a geologic period and system that extends from the end of the Devonian period about 359 2 ± 2. 5 Mya (in North America, the beginning of the Mississippian subperiod of the Carboniferous) (ICS 2004).

Well into the 20th century, the Devonian was often quoted as being "the age of fishes", referring to the great diversification of various piscine groups in the period. While the development of fishes is of great importance from an anthropocentric point of view (inasmuch as they are our vertebrate relatives), the name is now avoided, as fishes were but one of several important groups to see extensive development on the Devonian (see under Devonian biota). Vertebrates are members of the Subphylum Vertebrata, Chordates with backbones or spinal columns The grouping sometimes includes The name is frequently found in older (and a few newer) works.

In nineteenth-century texts the Devonian has been called the "Old Red Age", after the red and brown terrestrial deposits known in the United Kingdom as the Old Red Sandstone in which early fossil discoveries were found. The Old Red Sandstone is a Rock formation of considerable importance to early Paleontology.

The Devonian has also erroneously been characterized as a "greenhouse age", due to sampling bias: most of the early Devonian-age discoveries came from the strata of western Europe and eastern North America, which at the time straddled the Equator as part of the supercontinent of Euramerica where fossil signatures of widespread reefs indicate tropical climates that were warm and moderately humid but in fact the climate in the Devonian differed greatly between epochs and geographic regions. A biased sample is a statistical sample of a population in which some members of the population are less likely to be included than others In Geology and related fields a stratum (plural strata) is a layer of rock or Soil with internally consistent characteristics that distinguishes Western Europe at its most general meaning means 'all the countries in the West of Europe ' The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. Climate encompasses the temperatures humidity rainfall atmospheric particle count and numerous other meteorogical factors in a given region over long periods of The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other For example, during the Early Devonian, arid conditions were prevalent through much of the world including Siberia, Australia, North America, and China, but Africa and South America had a warm temperate climate. South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a In the Late Devonian, by contrast, arid conditions were less prevalent across the world and temperate climates were more common.

Devonian subdivisions

The Devonian Period is formally broken into Early, Middle, and Late subdivisions. The rocks corresponding to these epochs are referred to as belonging to the Lower, Middle, and Upper parts of the Devonian System. The international standard faunal stages from youngest to oldest are:

Late (most recent)

• Famennian
• Frasnian

Middle

• Givetian
• Eifelian

Early (oldest)

• Emsian
• Pragian
• Lochkovian

Devonian palaeogeography

Geography of the Devonian world

The Devonian period was a time of great tectonic activity, as Laurasia and Gondwanaland drew closer together. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere Laurasia (lɔˈreɪʃiə lɔˈreɪʒə was a Supercontinent that most recently existed as a part of the split of the Pangaean supercontinent in the late Mesozoic Gondwana (ɡɒnˈdwɑːnə originally Gondwanaland) was a southern Supercontinent that existed about 500 to 200 Ma ago

The continent Euramerica (or Laurussia) was created in the early Devonian by the collision of Laurentia and Baltica, which rotated into the natural dry zone along the Tropic of Capricorn, which is formed as much in Paleozoic times as nowadays by the convergence of two great airmasses, the Hadley cell and the Ferrel cell. Euramerica (also known as Laurussia or Old Red Continent) was a minor Supercontinent created in the Devonian as the result of a collision between Laurentia (also known as the North American craton) like all Craton land was created as continents moved about the surface of the Earth Baltica redirects here For the Russian beer, see Baltika Breweries Baltica is a name applied by geologists to a late- Proterozoic, For the novel by Henry Miller, see Tropic of Capricorn (novel. The Hadley cell is a circulation pattern that dominates the tropical atmosphere with rising motion near the equator poleward flow 10-15 kilometers above the surface descending motion Atmospheric circulation is the large-scale movement of air and the means (together with the smaller Ocean circulation) by which Heat is distributed on the surface In these near-deserts, the Old Red Sandstone sedimentary beds formed, made red by the oxidized iron (hematite) characteristic of drought conditions. The Old Red Sandstone is a Rock formation of considerable importance to early Paleontology. Hematite, also spelt hæmatite, is the Mineral form of Iron(III oxide (Fe2O3 one of several Iron oxides

Near the equator, Pangaea began to consolidate from the plates containing North America and Europe, further raising the northern Appalachian Mountains and forming the Caledonian Mountains in Great Britain and Scandinavia. The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the Pangaea, Pangæa or Pangea (pænˈdʒiːə from παν pan, meaning entire, and Γαῖα Gaea, meaning Earth in Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere The Appalachian Mountains ( often called the Appalachians, are a vast system of mountains in eastern North America. The Caledonian orogeny is a mountain building event recorded in the Mountains and Hills of northern Scotland, Ireland, England, See also Kingdom of Great Britain Great Britain (Breatainn Mhòr Prydain Fawr Breten Veur Graet Breetain is the larger of the two main islands Terminology and usage As a cultural term "Scandinavia" has no official definition and is subject to usage by those who identify with the culture in question as well

The west coast of Devonian North America, by contrast, was a passive margin with deep silty embayments, river deltas and estuaries, in today's Idaho and Nevada; an approaching volcanic island arc reached the steep slope of the continental shelf in Late Devonian times and began to uplift deep water deposits, a collision that was the prelude to the mountain-building episode of Mississippian times called the Antler orogeny [2]. The State of Idaho ( is a state in the Pacific Northwest region of the United States of America. Nevada ( is a state located in the western region of the United States of America. A volcanic arc is a chain of volcanic islands or Mountains formed by Plate tectonics as an oceanic Tectonic plate subducts under The Antler orogeny is a mountain-building episode that is named for Antler Peak at Battle Mountain Nevada.

The southern continents remained tied together in the supercontinent of Gondwana. A continent is one of several large Landmasses on Earth. They are generally identified by Convention rather than any strict criteria with seven regions In Geology, a supercontinent is a Landmass comprising more than one Continental core or Craton. The remainder of modern Eurasia lay in the Northern Hemisphere. Sea levels were high worldwide, and much of the land lay submerged under shallow seas, where tropical reef organisms lived. In nautical terminology a reef is a rock, sandbar, or other feature lying beneath the surface of the water (six fathoms or less at low water

The deep, enormous Panthalassa (the "universal ocean") covered the rest of the planet. Panthalassa ( Greek, meaning 'all seas' also known as the Panthalassic Ocean, was the vast global Ocean that surrounded the Supercontinent A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is Other minor oceans were Paleo-Tethys, Proto-Tethys, Rheic Ocean, and Ural Ocean (which was closed during the collision with Siberia and Baltica). The Paleo-Tethys Ocean was an ancient Paleozoic Ocean. It was located between the Paleocontinent Gondwana and the so called Hunic terranes The Proto-Tethys Ocean was an ancient Ocean that existed from the latest Ediacaran to the Carboniferous (550-330 Ma) The Rheic Ocean was an Ocean in the Paleozoic Era that existed between to the north the Continent of Baltica (northern Ural Ocean was a small ancient ocean that was situated between Siberia and Baltica. Siberia is the Craton located in the heart of the region of Siberia.

Devonian rocks are oil and gas producers in some areas.

Devonian biota

Devonian fishes, from Joseph Smits "from Nebula to Man", 1905, showing early shark, ray-finned fishes, a lungfish and the placoderm Bothriolepis. Sharks ( Superorder Selachimorpha) are a type of Fish with a full cartilaginous Skeleton and a highly streamlined body The Actinopterygii (the plural form of Actinopterygius) comprise the class of the ray-finned fishes. Lungfish are freshwater fish belonging to the Subclass Dipnoi. The Placodermi were a class of armoured Prehistoric fishes known from Fossils which lived from the late Silurian to the end of the Devonian Bothriolepis ("pitted scale" or "trench scale" was the most successful Genus of Antiarch Placoderms if not the

Fossil trilobite Ductina vietnamica from the Devonian of China

SEM image of a hederelloid from the Devonian of Michigan (largest tube diameter is 0. Hederellids are Extinct colonial Animals with calcitic tubular branching Exoskeletons They range from the Silurian to the Permian and 75 mm).

A Devonian spiriferid brachiopod from Ohio which served as a host substrate for a colony of hederelloids. Brachiopods (from Latin brachium, arm + New Latin -poda, foot are a small phylum of Benthic Invertebrates Also Ohio ( is a Midwestern state of the United States. As part of the Great Lakes region, Ohio has long been a cultural and geographical crossroads Hederellids are Extinct colonial Animals with calcitic tubular branching Exoskeletons They range from the Silurian to the Permian and The specimen is 5 cm wide.

Marine biota

Sea levels in the Devonian were generally high. Marine faunas continued to be dominated by bryozoa, diverse and abundant brachiopods, the enigmatic hederelloids, and corals. Bryozoans are tiny colonial Animals that generally build stony Skeletons of Calcium carbonate, superficially similar to Coral (although some Brachiopods (from Latin brachium, arm + New Latin -poda, foot are a small phylum of Benthic Invertebrates Also Hederellids are Extinct colonial Animals with calcitic tubular branching Exoskeletons They range from the Silurian to the Permian and Corals are Marine organisms from the class Anthozoa and exist as small Sea anemone –like Polyps typically in colonies of many Lily-like crinoids were abundant, and trilobites were still fairly common, but less diverse than in earlier periods due to the abundance of mobile swimming predators such as early sharks and predatory bony fish (Osteichthyes) such as Dunkleosteus. Crinoids, also known as sea lilies or feather-stars, are marine animals that make up the class Crinoidea of the Echinoderms (phylum Echinodermata Trilobites ("three-lobes" are extinct Arthropods that form the class Trilobita. Dunkleosteus (From "(David Dunkle" + Greek: osteus / οστεος = bone; meaning "Dunkle's Bone" is a The ostracoderms were joined in the mid-Devonian by the first jawed fishes and were declining in diversity and were being out competed by the jawed fish in both the sea and fresh water, also the great armored placoderms, as well as the first sharks and ray-finned fish. Ostracoderms ("shell-skinned" are any of several groups of extinct, primitive jawless Fishes that were covered in an armor of bony plates Freshwater is a word that refers to bodies of water such as Ponds lakes rivers and streams containing low concentrations of dissolved Salts and other Total dissolved The Placodermi were a class of armoured Prehistoric fishes known from Fossils which lived from the late Silurian to the end of the Devonian The Actinopterygii (the plural form of Actinopterygius) comprise the class of the ray-finned fishes. The first abundant species of shark, the Cladoselache, appeared in the oceans during the Devonian period. Cladoselache is a Genus of extinct Shark. It appeared in the Devonian period They became abundant and diverse. In the late Devonian the lobe-finned fish appeared, giving rise to the first tetrapods. Sarcopterygii (from Greek σαρξ sarx, flesh and πτερυξ pteryx, fin is traditionally the class of lobe-finned Fishes consisting Tetrapods ( Greek τετραποδη tetrapoda, Latin Quadruped, "four-footed" are Vertebrate Animals

The first Ammonites also appeared during or slightly before the early devonian period around 400 million years ago. Ammonites are an extinct group of marine animals of the subclass Ammonoidea in the class Cephalopoda phylum [3]

A recently discovered fossil of a fish embryo attached to its mother by an umbilical cord in 380 million year old Devonian strata provides the earliest fossil evidence of vertebrates giving live birth to their young. ^[8]

Reefs

A great barrier reef, now left high and dry in the Kimberley Basin of northwest Australia, once extended a thousand kilometers, fringing a Devonian continent. The Kimberley is one of the nine Regions of Western Australia. For a topic outline on this subject see List of basic Australia topics. Reefs in general are built by various carbonate-secreting organisms that have the ability to erect wave-resistant frameworks close to sea level. In Chemistry, a carbonate is a salt or Ester of Carbonic acid. The main contributors of the Devonian reefs were unlike modern reefs, which are constructed mainly by corals and calcareous algae. Algae ( sing. alga are a large and diverse group of simple typically Autotrophic organisms ranging from Unicellular to Multicellular forms They were composed of calcareous algae and coral-like stromatoporoids, and tabulate and rugose corals, in that order of importance. Stromatoporoidea is an order of colonial aquatic Invertebrates that until recently was believed to have gone extinct in the Devonian. The Rugosa Rose is also sometimes just called "Rugosa" The Rugosa, also called the Tetracoralla, are an extinct order

Terrestrial biota

By the Devonian Period, life was well underway in its colonization of the land. The moss forests and bacterial and algal mats of the Silurian were joined early in the period by primitive rooted plants that created the first stable soils and harbored arthropods like mites, scorpions and myriapods (although arthropods appeared on land much earlier than in the Early Devonian and the existence of fossils such as Climactichnites suggest that land arthropods may have appeared as early as the Cambrian period). Mosses are small soft Plants that are typically 1–10  cm (0 The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443 Plants are living Organisms belonging to the kingdom Plantae. Soil, often typeset as SOiL, is a four piece rock band from Chicago Illinois United States founded by Shaun Glass Tom Schofield Tim King and Adam Zadel Mites, along with Ticks belong to the subclass Acarina (also known as Acari and the class Arachnida Mites are among the most diverse and successful Scorpions are eight-legged Carnivorous Arthropods They are members of the order Scorpiones within the class Arachnida. Myriapoda is a Subphylum of Arthropods containing Millipedes Centipedes and others Climactichnites is an enigmatic late Cambrian fossil formed on sandy tidal flats around. The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with Early Devonian plants did not have roots or leaves like the plants most common today, and many had no vascular tissue at all. They probably spread largely by vegetative growth, and did not grow much more than a few centimeters tall. Also the first possible fossils of insects appeared around 416 Ma in the Early Devonian. Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described Annum is one form of the Latin noun meaning Year, not a form normally used for derivatives in modern languages the accusative singular

By the Devonian, shrub-like forests of small, primitive plants existed: lycophytes, sphenophytes, ferns, and progymnosperms had evolved. The Division Lycopodiophyta (sometimes called Lycophyta) is a tracheophyte subdivision of the Kingdom Plantae It is the oldest extant (living A fern is any one of a group of about 20000 Species of Plants classified in the phylum or division Pteridophyta, also known as Filicophyta eVolution is the third Album by eLDee, it was due to be released in 2008 Most of these plants had true roots and leaves, and many were quite tall. In the Late Devonian, the tree-like ancestral fern Archaeopteris and the giant cladoxylopsid trees grew with true wood. Archaeopteris is an Extinct genus of tree-like plants with Fern -like leaves The cladoxylopsids are a group of Plants known only as Fossils that are thought to be ancestors of Ferns and Horsetails They had a central trunk Wood is hard fibrous lignified structural tissue produced as secondary Xylem in the stems of Woody plants notably trees but also shrubs (See also: lignin. Lignin or lignen is a complex Chemical compound most commonly derived from Wood and an integral part of the secondary Cell walls of Plants ) These are the oldest known trees of the world's first forests. Prototaxites was the fruiting body of an enormous fungus that stood more than 8 meter tall. The genus Prototaxites (ˌproʊtoʊˈtæksɨtiːz describes terrestrial organisms known only from fossils dating from the Silu - Devonian, approximately By the end of the Devonian, the first seed-forming plants had appeared. This rapid appearance of so many plant groups and growth forms has been called the "Devonian Explosion". Primitive arthropods co-evolved with this diversified terrestrial vegetation structure. The evolving co-dependence of insects and seed-plants that characterizes a recognizably modern world had its genesis in the Late Devonian. The development of soils and plant root systems probably led to changes in the speed and pattern of erosion and sediment deposition. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind The rapid evolution of a terrestrial ecosystem containing copious animals opened the way for the first vertebrates to seek out a terrestrial living. Vertebrates are members of the Subphylum Vertebrata, Chordates with backbones or spinal columns The grouping sometimes includes By the end of the Devonian, early amphibians and arthropods were solidly established on the land. Prehistoric amphibian Amphibians (class Amphibia such as Frogs Toads Salamanders Newts Gymnophiona, Sirens and

The earliest known trees, from the genus Wattieza, appeared in the Late Devonian around 380 Ma. Wattieza was a Genus of Prehistoric trees that existed in the mid-Devonian that belong to the Cladoxylopsids close relatives of the Annum is one form of the Latin noun meaning Year, not a form normally used for derivatives in modern languages the accusative singular [4]

The 'greening' of the continents acted as a carbon dioxide sink, and atmospheric levels of this greenhouse gas may have dropped. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five Greenhouse gases are gaseous constituents of the atmosphere bothnatural and anthropogenic that absorb and emit radiation at specific wavelengths within the spectrum of thermal infrared This may have cooled the climate and led to a massive extinction event. An extinction event (also known as mass extinction; extinction-level event, ELE is a sharp decrease in the number of Species in a relatively short period See Late Devonian extinction. The Late Devonian extinction was one of five major Extinction events in the history of the Earth's Biota.

Late Devonian extinction

Comparison of the three episodes of extinction in the Late Devonian ("Late D") to other mass extinction events in Earth's history. The history of Earth covers approximately 46 billion years (4567000000 years from Earth ’s formation out of the Solar nebula to the present Data based on marine genera. A genus (plural genera from Γένος Latin genus "descent family type gender" is a low-level Taxonomic

Main article: Late Devonian extinction

A major extinction occurred at the beginning of the last phase of the Devonian period, the Famennian faunal stage, (the Frasnian-Famennian boundary), about 364 million years ago, when all the fossil agnathan fishes, save for the psammosteid heterostracans, suddenly disappeared. The Late Devonian extinction was one of five major Extinction events in the history of the Earth's Biota. The Psammosteidae are a family of flattened benthic jawless Vertebrates that lived in marine and Estuary environments in Europe Russia & North America Heterostraci ("Different scales" is an Extinct class of jawless Vertebrate that lived primarily in marine and Estuary A second strong pulse closed the Devonian period. The Late Devonian extinction was one of five major extinction events in the history of the Earth's biota, more drastic than the familiar extinction event that closed the Cretaceous.

The Devonian extinction crisis primarily affected the marine community, and selectively affected shallow warm-water organisms rather than cool-water organisms. The most important group to be affected by this extinction event were the reef-builders of the great Devonian reef-systems .

Amongst the severely affected marine groups were the brachiopods, trilobites, ammonites, conodonts, and acritarchs, as well as jawless fish, and all placoderms. Brachiopods (from Latin brachium, arm + New Latin -poda, foot are a small phylum of Benthic Invertebrates Also Ammonites are an extinct group of marine animals of the subclass Ammonoidea in the class Cephalopoda phylum Conodonts are extinct chordates resembling eels classified in the class Conodonta. Acritarchs are small organic Fossils present from approximately to the present Freshwater species, including our tetrapod ancestors, were less affected.

Reasons for the late Devonian extinctions are still speculative. The Canadian paleontologist Digby McLaren suggested in 1969 that the Devonian extinction events were caused by an asteroid impact; however, little evidence supports the existence of a Devonian crater large enough. Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page Palaeontology redirects here For the Scientific journal, see Palaeontology (journal. Dr Digby Johns McLaren PhD FRSC ( December 11, 1919 &ndash December 8, 2004) was a Canadian geologist and

Notes

References

• Ogg, Jim; June, 2004, Overview of Global Boundary Stratotype Sections and Points (GSSP's) http://www.stratigraphy.org/gssp.htm Accessed April 30, 2006.
• Palaeos

See also

• Geologic timescale
• Phacops rana: a Devonian trilobite. The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other Phacops rana ( Eldgredgeops rana) is a species of Trilobite from the middle Devonian period
• List of fossil sites (with link directory)

External links

• The Devonian times - an excellent and frequently updated resource focussing on the Devonian period
• UC Berkeley site introduces the Devonian.
• Devonian reef system in northwest Australia.
• International Commission on Stratigraphy (ICS). This is a worldwide list of important and/or well-known localities where Fossils have been found Geologic Time Scale 2004. Retrieved on Sept 19, 2005. Events 335 - Dalmatius is raised to the rank of Caesar by his uncle Constantine I. Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar.
• Falls of the Ohio State Park USA, Indiana. Falls of the Ohio State Park is a State park in Indiana. It is located on the banks of the Ohio River at Clarksville Indiana, across from One of the largest exposed Devonian fossil beds in the world.
• Examples of Devonian Fossils