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Devonian Conodonts
The Devonian ( ) is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at million years ago ( Ma), to the beginning of the succeeding Carboniferous period at Ma. It is the fourth period of both the Paleozoic and the Phanerozoic. It is named after Devon, South West England, where rocks from this period were first studied. The first significant evolutionary radiation of life on land occurred during the Devonian, as free- sporing land plants (pteridophytes) began to spread across dry land, forming extensive coal forests which covered the continents. By the middle of the Devonian, several groups of vascular plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants ( pteridospermatophytes) appeared. This rapid evolution and colonization process, which had begun during the Silurian, is known as the Silurian-Devonian Terrestrial R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Commission On Stratigraphy
The International Commission on Stratigraphy (ICS), sometimes unofficially referred to as the International Stratigraphic Commission, is a daughter or major subcommittee grade scientific organization that concerns itself with stratigraphy, stratigraphical, geology, geological, and chronology, geochronological matters, worldwide. It is the largest subordinate body of the International Union of Geological Sciences (IUGS). The ICS is essentially a permanent working committee, working subcommittee, which meets far more regularly than the quadrennial meetings scheduled by the IUGS, when it meets as a congress or committee, membership of the whole. Aims One of its main aims, a project begun in 1974, is to establish a multidisciplinary standard and global geologic time scale that will ease paleontology, paleontological and geobiology, geobiological comparisons region to region by benchmarks with stringent and rigorous strata criteria called Global Boundary Stratotype Section and Points ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silurian
The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of the Paleozoic Era, and the third of twelve periods of the Phanerozoic Eon. 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 a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out. One important event in this period was the initial establishment of terrestrial life in what is known as the Silurian-Devonian Terrestrial Revolution: vascular plants emerged from more primitive land plants, dikaryan fungi started expanding and diversifying along with glomeromycotan fungi, and three groups of arthropods ( myriapods, arachnids and hexapods) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vascular Plant
Vascular plants (), also called tracheophytes (, ) or collectively tracheophyta (; ), are plants that have lignin, lignified tissues (the xylem) for conducting water and minerals throughout the plant. They also have a specialized non-lignified Tissue (biology), tissue (the phloem) to conduct products of photosynthesis. The group includes most embryophyte, land plants ( accepted known species) excluding mosses. Vascular plants include the clubmosses, Equisetum, horsetails, ferns, gymnosperms (including conifers), and angiosperms (flowering plants). They are contrasted with nonvascular plants such as mosses and green algae. Scientific names for the vascular plants group include Tracheophyta, Tracheobionta and Equisetopsida sensu lato, Equisetopsida ''sensu lato''. Some early land plants (the rhyniophytes) had less developed vascular tissue; the term eutracheophyte has been used for all other vascular plants, including all living ones. Historically, vascular plants were known as "hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coal Forest
Coal forests were the vast swathes of freshwater swamp and riparian forests that covered much of the lands on Earth's tropical regions during the late Carboniferous ( Pennsylvanian) and Permian periods.Cleal, C. J. & Thomas, B. A. (2005). "Palaeozoic tropical rainforests and their effect on global climates: is the past the key to the present?" ''Geobiology'', ''3'', p. 13-31. As plant matter from these wetland forests decayed, enormous deposits of peat accumulated, which later became buried and converted into coal over the subsequent geologic eras. Overview Much of the carbon in the peat deposits produced by coal forests came from photosynthetic fixation of atmospheric carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ..., which released the accompanying split-o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dry Land
Land, also known as dry land, ground, or earth, is the solid terrestrial surface of Earth not submerged by the ocean or another body of water. It makes up 29.2% of Earth's surface and includes all continents and islands. Earth's land surface is almost entirely covered by regolith, a layer of rock, soil, and minerals that forms the outer part of the crust. Land plays an important role in Earth's climate system, being involved in the carbon cycle, nitrogen cycle, and water cycle. One-third of land is covered in trees, another third is used for agriculture, and one-tenth is covered in permanent snow and glaciers. The remainder consists of desert, savannah, and prairie. Land terrain varies greatly, consisting of mountains, deserts, plains, plateaus, glaciers, and other landforms. In physical geology, the land is divided into two major categories: Mountain ranges and relatively flat interiors called cratons. Both form over millions of years through plate tectonics. Streams ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pteridophyte
A pteridophyte is a vascular plant (with xylem and phloem) that reproduces by means of spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as " cryptogams", meaning that their means of reproduction is hidden. They are also the ancestors of the plants we see today. Ferns, horsetails (often treated as ferns), and lycophytes ( clubmosses, spikemosses, and quillworts) are all pteridophytes. However, they do not form a monophyletic group because ferns (and horsetails) are more closely related to seed plants than to lycophytes. "Pteridophyta" is thus no longer a widely accepted taxon, but the term ''pteridophyte'' remains in common parlance, as do ''pteridology'' and ''pteridologist'' as a science and its practitioner, for example by the International Association of Pteridologists and the Pteridophyte Phylogeny Group. Etymology The name ''Pteridophyte'' is a Neo-Latin compound word created by English speakers around 1880. It is for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Land Plant
The embryophytes () are a clade of plants, also known as Embryophyta (Plantae ''sensu strictissimo'') () or land plants. They are the most familiar group of photoautotrophs that make up the vegetation on Earth's dry lands and wetlands. Embryophytes have a common ancestor with green algae, having emerged within the Phragmoplastophyta clade of freshwater charophyte green algae as a sister taxon of Charophyceae, Coleochaetophyceae and Zygnematophyceae. Embryophytes consist of the bryophytes and the polysporangiophytes. Living embryophytes include hornworts, liverworts, mosses, lycophytes, ferns, gymnosperms and angiosperms (flowering plants). Embryophytes have biological life cycle, diplobiontic life cycles. The embryophytes are informally called "land plants" because they thrive primarily in Terrestrial ecosystem, terrestrial habitats (despite aquatic plant, some members having evolved secondarily to live once again in semiaquatic/aquatic habitats), while the related green algae ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spore
In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the Biological life cycle, life cycles of many plants, algae, fungus, fungi and protozoa. They were thought to have appeared as early as the mid-late Ordovician period as an adaptation of early land plants. Bacterial spores are not part of a sexual cycle, but are resistant structures used for survival under unfavourable conditions. Myxozoan spores release amoeboid infectious germs ("amoebulae") into their hosts for parasitic infection, but also reproduce within the hosts through the pairing of two nuclei within the plasmodium, which develops from the amoebula. In plants, spores are usually haploid and unicellular and are produced by meiosis in the sporangium of a diploid sporophyte. In some rare cases, a diploid spore is also p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of Life
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as ''Ga'', for '' gigaannum'') and evidence suggests that life emerged prior to 3.7 Ga. The similarities among all known present-day species indicate that they have diverged through the process of evolution from a common ancestor. The earliest clear evidence of life comes from biogenic carbon signatures and stromatolite fossils discovered in 3.7 billion-year-old metasedimentary rocks from western Greenland. In 2015, possible "remains of biotic life" were found in 4.1 billion-year-old rocks in Western Australia. There is further evidence of possibly the oldest forms of life in the form of fossilized microorganisms in hydrothermal vent precipitates from the Nuvvuagittuq Belt, that may have lived as early as 4.28 billion years ago, not long after the oceans formed 4.4 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolutionary Radiation
An evolutionary radiation is an increase in taxonomic diversity that is caused by elevated rates of speciation, that may or may not be associated with an increase in morphological disparity. A significantly large and diverse radiation within a relatively short geologic time scale (e.g. a period or epoch) is often referred to as an explosion. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment, they are termed adaptive radiations. Examples Perhaps the most familiar example of an evolutionary radiation is that of placental mammals immediately after the extinction of the non-avian dinosaurs at the end of the Cretaceous, about 66 million years ago. At that time, the placental mammals were mostly small, insect-eating animals similar in size and shape to modern shrews. By the Eocene (58–37 million years ago), they had evolved into such diverse forms as bats, whales, and hor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South West England
South West England, or the South West of England, is one of the nine official regions of England, regions of England in the United Kingdom. Additionally, it is one of four regions that altogether make up Southern England. South West England consists of the counties of Cornwall (including the Isles of Scilly), Dorset, Devon, Bristol, Gloucestershire, Somerset and Wiltshire. Cities and large towns in the region include Bath, Somerset, Bath, Bristol, Bournemouth, Cheltenham, Exeter, Gloucester, Plymouth and Swindon. It is geographically the largest of the nine regions of England with a land area of , but the third-least populous, with an estimated residents in . The region includes the West Country and much of the ancient kingdom of Wessex. It includes two entire national parks of England and Wales, national parks, Dartmoor and Exmoor (a small part of the New Forest is also within the region); and four List of World Heritage Sites in the United Kingdom, World Heritage Sites: Ston ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devon
Devon ( ; historically also known as Devonshire , ) is a ceremonial county in South West England. It is bordered by the Bristol Channel to the north, Somerset and Dorset to the east, the English Channel to the south, and Cornwall to the west. The city of Plymouth is the largest settlement, and the city of Exeter is the county town. The county has an area of and a population of 1,194,166. The largest settlements after Plymouth (264,695) are the city of Exeter (130,709) and the Seaside resort, seaside resorts of Torquay and Paignton, which have a combined population of 115,410. They all are located along the south coast, which is the most populous part of the county; Barnstaple (31,275) and Tiverton, Devon, Tiverton (22,291) are the largest towns in the north and centre respectively. For local government purposes Devon comprises a non-metropolitan county, with eight districts, and the Unitary authorities of England, unitary authority areas of Plymouth City Council, Plymouth an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
