query: part_of silurian
supports: Devon (archaically known as Devonshire) is a county of England, reaching from the Bristol Channel in the north to the English Channel in the south. It is part of South West England, bounded by Cornwall to the west, Somerset to the northeast, and Dorset to the east. The City of Exeter is the county town; seven other districts of East Devon, Mid Devon, North Devon, South Hams, Teignbridge, Torridge, and West Devon are under the jurisdiction of Devon County Council; Plymouth and Torbay are each a part of Devon but administered as unitary authorities. Combined as a ceremonial county, Devon's area is and its population is about 1.1 million. Placodermi (from the Greek  = plate and  = skin, literally "plate-skinned") is an extinct class of armoured prehistoric fish, known from fossils, which lived from the Silurian to the end of the Devonian Period. Their head and thorax were covered by articulated armoured plates and the rest of the body was scaled or naked, depending on the species. Placoderms were among the first jawed fish; their jaws likely evolved from the first of their gill arches. Placoderms are paraphyletic, and consist of several distinct outgroups or sister taxa to all living jawed vertebrates, which originated among their ranks. This is illustrated by a 419-million-year-old fossil, "Entelognathus", from China, which is the only known placoderm with a type of bony jaw like that found in modern bony fishes. This includes a dentary bone, which is found in humans and other tetrapods. The jaws in other placoderms were simplified and consisted of a single bone. Placoderms were also the first fish to develop pelvic fins, the precursor to hindlimbs in tetrapods, as well as true teeth. 380-million-year-old fossils of three other genera, "Incistoscutum", "Materpiscis" and "Austroptyctodus", represent the oldest known examples of live birth. The Ordovician is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.2 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The Ordovician, named after the Celtic tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in northern Wales into the Cambrian and Silurian periods, respectively. Lapworth, recognized that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian periods, and placed them in a period of their own. It received international sanction in 1960, when it was adopted as an official period of the Paleozoic Era by the International Geological Congress. The Cambrian Period (or ) was the first geological period of the Paleozoic Era, of the Phanerozoic Eon. The Cambrian lasted 55.6 million years from the end of the preceding Ediacaran Period 541 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established (as Cambrian series) by Adam Sedgwick, who named it after Cambria, the Latinised form of "Cymru", the Welsh name for Wales, where Britain's Cambrian rocks are best exposed. The Cambrian is unique in its unusually high proportion of lagerstätte sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian biology surpasses that of some later periods. Roderick Impey Murchison, 1st Baronet KCB DCL FRS FRSE FLS PRGS PBA MRIA (22 February 1792  22 October 1871) was a Scottish geologist who first described and investigated the Silurian system. England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west. The Irish Sea lies northwest of England and the Celtic Sea lies to the southwest. England is separated from continental Europe by the North Sea to the east and the English Channel to the south. The country covers five-eighths of the island of Great Britain (which lies in the North Atlantic) in its centre and south; and includes over 100 smaller islands such as the Isles of Scilly, and the Isle of Wight. A continent is one of several very large landmasses on Earth. Generally identified by convention rather than any strict criteria, up to seven regions are commonly regarded as continents. Ordered from largest in size to smallest, they are: Asia, Africa, North America, South America, Antarctica, Europe, and Australia. In geology, areas of continental crust include regions covered with water. FOREST (short for "Freedom Organisation for the Right to Enjoy Smoking Tobacco") is a United Kingdom political pressure group which campaigns against tobacco control activity. The Devonian is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, where rocks from this period were first studied.
  The first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. Various terrestrial arthropods also became well-established. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the "Age of Fish". The first ray-finned and lobe-finned bony fish appeared, while the placodermi began dominating almost every known aquatic environment. FOSSIL is a standard protocol for allowing serial communication for telecommunications programs under the DOS operating system. FOSSIL is an acronym for "Fido Opus SEAdog Standard Interface Layer". "Fido" refers to FidoBBS, "Opus" refers to Opus-CBCS BBS, and "SEAdog" refers to a Fidonet compatible mailer. The standards document that defines the FOSSIL protocol is maintained by the Fidonet Technical Standards Committee. In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges, or opens new environmental niches. Starting with a recent single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different morphological and physiological traits. An example of adaptive radiation would be the avian species of the Hawaiian honeycreepers. Via natural selection, these birds adapted rapidly and converged based on the different environments of the Hawaiian islands. The Carboniferous is a geologic period and system that spans 60 million years from the end of the Devonian Period million years ago (Mya), to the beginning of the Permian Period, Mya. The name "Carboniferous" means "coal-bearing" and derives from the Latin words "carb" ("coal") and "fer" ("I bear, I carry"), and was coined by geologists William Conybeare and William Phillips in 1822. Based on a study of the British rock succession, it was the first of the modern 'system' names to be employed, and reflects the fact that many coal beds were formed globally during that time. The Carboniferous is often treated in North America as two geological periods, the earlier Mississippian and the later Pennsylvanian. Adam Sedgwick (22 March 1785  27 January 1873) was one of the founders of modern geology. He proposed the Devonian period of the geological timescale. Later, he proposed the Cambrian period, based on work which he did on Welsh rock strata. An arthropod (from Greek "arthro-", joint + "podos", foot) is an invertebrate animal having an exoskeleton (external skeleton), a segmented body, and jointed appendages (paired appendages). Arthropods form the phylum Arthropoda, which includes the insects, arachnids, myriapods, and crustaceans. 
  Arthropods are characterized by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. The rigid cuticle inhibits growth, so arthropods replace it periodically by moulting. Their versatility has enabled them to become the most species-rich members of all ecological guilds in most environments. They have over a million described species, making up more than 80% of all described living animal species, some of which, unlike most animals, are very successful in dry environments. The Paleozoic (or Palaeozoic) Era (from the Greek "palaios" (), "old" and "zoe" (), "life", meaning "ancient life") is the earliest of three geologic eras of the Phanerozoic, from . It is the longest of the Phanerozoic eras, and is subdivided into six geologic periods (from oldest to youngest): the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. The Paleozoic comes after the Neoproterozoic era of the Proterozoic and is followed by the Mesozoic. Charles Lapworth, FRS, FGS (20 September 1842  13 March 1920) was an English geologist who pioneered faunal analysis using index fossils and identified the Ordovician period. The Ordovices were one of the Celtic tribes living in Great Britain before the Roman invasion. Their tribal lands were located in present-day North Wales and England between the Silures to the south and the Deceangli to the north-east. The Ordovices were conquered by the Roman governor Gnaeus Julius Agricola in the campaign of AD 7778. The Silurian is a geologic period and system that extends from the end of the Ordovician Period , at 443.8 million years ago ( mya ) , to the beginning of the Devonian Period . As with other geologic periods , the rock beds that define the period 's start and end are well identified , but the exact dates are uncertain by several million years . The base of the Silurian is set at a major extinction event when 60 % of marine species were wiped out . See Ordovician - Silurian extinction events . A significant evolutionary milestone during the Silurian was the diversification of jawed and bony fish . Life also began to appear on land in the form of small , moss - like , vascular plants that grew beside lakes , streams , and coastlines , and also in the form of small terrestrial arthropods . However , terrestrial life would not greatly diversify and affect the landscape until the Devonian . A fish is any member of a group of organisms that consist of all gill-bearing aquatic craniate animals that lack limbs with digits. They form a sister group to the tunicates, together forming the olfactores. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Tetrapods emerged within lobe-finned fishes, so cladistically they are fish as well. However, traditionally fish are rendered obsolete or paraphyletic by excluding the tetrapods (i.e., the amphibians, reptiles, birds and mammals which all descended from within the same ancestry). Because in this manner the term "fish" is defined negatively as a paraphyletic group, it is not considered a formal taxonomic grouping in systematic biology. The traditional term pisces (also ichthyes) is considered a typological, but not a phylogenetic classification. Vascular plants (from Latin "vasculum": duct), also known as tracheophytes (from the equivalent Greek term "trachea") and also higher plants, form a large group of plants (c. 308,312 accepted known species ) that are defined as those land plants that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They also have a specialized non-lignified tissue (the phloem) to conduct products of photosynthesis. Vascular plants include the clubmosses, horsetails, ferns, gymnosperms (including conifers) and angiosperms (flowering plants). Scientific names for the group include Tracheophyta and Tracheobionta.
candidates: africa animal biology bristol channel c cambrian china city class communication congress country day earth england english channel event evolutionary biology exoskeleton february fish foot forest geological period geology gill irish sea islands january joint march name north america north sea october operating system paleozoic phylum population proterozoic radiation rock september skin species system the city welsh work year
answer: paleozoic