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Isomer (Proarticulata)
Isomer (Greek ''isos'' = "equal", ''méros'' = "part") is an element of transverse body articulation of the bilateral fossil animals of the Phylum Proarticulata from the Ediacaran (Vendian) period. This term has been proposed by Andrey Yu. Ivantsov, a Russian paleontologist from the Laboratory of the Precambrian organisms, Paleontological Institute, Russian Academy of Sciences. Morphology Proarticulatan isomers are distinct from the segments of the Annelida and Panarthropoda, as each of these elements occupies only half of width of a body and are organized in an alternating pattern relatively to the axis of the body. In other words, although proarticulatans are bilaterally symmetrical, one side is not the direct mirror image of its opposite. Opposite isomers of left and right side are located with displacement of half of its width. This phenomenon is described as the symmetry of gliding reflection.M. A. Fedonkin (1985). "Systematic Description of Vendian Metazoa". In Sokolov, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yorgia
''Yorgia waggoneri'' is a discoid Ediacaran organism. It has a low, segmented body consisting of a short wide "head", no appendages, and a long body region, reaching a maximum length of . It is classified within the extinct animal phylum Proarticulata. Etymology The generic name ''Yorgia'' comes from the Yorga river on the Zimnii Bereg (Winter Coast) of the White Sea, where the first specimens were found. The specific name ''Yorgia waggoneri'' honors the American paleontologist Ben Waggoner, who found the first specimen. Morphology The body plan of the ''Yorgia'' and other proarticulates is unusual for solitary (non-colonial) metazoans. These bilateral organisms have segmented metameric bodies, but left and right transverse elements (isomers) are organized in an alternating pattern relatively to the axis of the body – they are not direct mirror images. This phenomenon is described as the symmetry of glide reflection, which is a characteristic also found in the similar ''Spri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proarticulata Classes
Proarticulata is a proposed phylum of extinct, bilaterally symmetrical animals known from fossils found in the Ediacaran (Vendian) marine deposits, and dates to approximately . The name comes from the Greek () = "before" and Articulata, i.e. prior to animals with true segmentation such as annelids and arthropods. This phylum was established by Mikhail A. Fedonkin in 1985 for such animals as '' Dickinsonia'', '' Vendia'', ''Cephalonega'', ''Praecambridium'' and currently many other Proarticulata are described (see list). Due to their simplistic morphology, their affinities and mode of life are subject to debate. They are almost universally considered to be metazoans, and due to possessing a clear central axis have been suggested to be stem-bilaterians. In the traditional interpretation, the Proarticulatan body is divided into transverse articulation (division) into isomers as distinct from the transverse articulation segments in annelids and arthropods, as their individual i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Onega Stepanovi
''Cephalonega stepanovi'' is a fossil organism from Ediacaran deposits of the Arkhangelsk Region, Russia. It was described by Mikhail A. Fedonkin in 1976 Name Its original genus name ''Onega'' comes from the Onega Peninsula of the White Sea, where the first fossils were found. The species name was given to honour V.A. Stepanov, who discovered the Ediacaran fossil site on the Letniy Bereg (" Summer Coast") in 1972, on the Onega Peninsula, the first Proterozoic site found in the Arkhangelsk Oblast. The original generic name is previously occupied by the hemipteran genus ''Onega'' Distant (1908). Ivantsov ''et al.'' (2019) coined a replacement generic name ''Cephalonega''. Morphology The small fossils, which range up to long, have oval outlines and low bodies with an articulated central zone built of isomers encircled by an undivided zone. The surface of the undivided region of ''Cephalonega'' is covered with small tubercles. ''Cephalonega'' was originally described ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phyllozoon
''Phyllozoon''(lit. "Leaf animal" in greek) is an Ediacaran imprint that resembles a proarticulatan and has been interpreted as a feeding trace. It usually occurs in long chains of imprints formed, presumably as the organism that made it moved. See also *List of Ediacaran genera This is a list of all described Ediacaran genera, including the Ediacaran biota. It contains 227 genera. References {{reflist, 30em * Ediacaran The Ediacaran Period ( ) is a geological period that spans 96 million years from the end ... References Fossils of Australia Dipleurozoa Ediacaran life Fossil taxa described in 1978 Trace fossils {{ediacaran-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yorgiidae
Yorgiidae is an extinct family of cephalozoans, which lived 635 million years ago. They were filter fed. Description Like most proarticulates, they present semi-bilateral symmetry. They had a discoid appearance, with the body segmented by isomers. Distribution Ediacaran of Russian Federation and South Australia. Gallery Archaeaspinus_fedonkini.jpg , ''Archaeaspinus fedonkini'' Photo_of_"Archaeaspinus_fedonkini"_fossil_Ivantsov_2007.png , ''Other fossil of Archaeaspinus fedonkini'' Yorgia_trace.jpg , ''Epibaion waggoneri, possible ichnofossil of Yorgia waggoneri'' See also * Cephalozoa References Cephalozoa Yorgiidae Ediacaran life Fossils of Russia {{Ediacaran-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Family (biology)
Family ( la, familia, plural ') is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae, but that family is commonly referred to as the "walnut family". What belongs to a family—or if a described family should be recognized at all—are proposed and determined by practicing taxonomists. There are no hard rules for describing or recognizing a family, but in plants, they can be characterized on the basis of both vegetative and reproductive features of plant species. Taxonomists often take different positions about descriptions, and there may be no broad consensus across the scientific community for some time. The publishing of new data and opini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanorus
''Cyanorus singularis'' is a small proarticulatan, closely related to ''Spriggina'' and '' Marywadea''. Its two largest pairs of appendages are located on the anterior part of the body. The anterior part of the body was most likely not segmented. The axial structure of it combines features of the ''Vendia'' species and ''Dickinsonia'' species. It was found in the Upper Vendian of the White Sea area, Arkhangel'sk Region. It is a White Sea Ediacaran fossil and it became extinct during the Late Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the .... Notes References {{Taxonbar, from=Q60760937 Ediacaran life Sprigginidae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marywadea
''Marywadea'' is a genus of Ediacaran biota shaped like an oval with a central ridge. It is a bilaterian organism as evidenced by its symmetry, vaguely resembling a very primitive trilobite. The fossil has an asymmetrical first chamber of the quilt. It has transverse ridges away from the central axis that may be gonads. The head is shaped as a semicircle and is the same width as the rest of the body. The ridges number about 50. There are two oval shapes below the head. ''Marywadea ovata'' is the only described species of the genus. Originally ''M. ovata'' was grouped under the genus ''Spriggina'', but recent research has moved the species into its own genus. It is most often interpreted as an early arthropod, annelid, or a member of Proarticulata, but as with all Ediacarian fauna its phylogeny remains uncertain. Initially, it was described as the second species of ''Spriggina''. The genus was established by Martin Glaessner in 1976, who named it after fellow paleontologist M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spriggina
''Spriggina'' is a genus of early bilaterian animals whose relationship to living animals is unclear. Fossils of ''Spriggina'' are known from the late Ediacaran period in what is now South Australia. ''Spriggina floundersi'' is the official fossil emblem of South Australia. It has been found nowhere else. The organism reached about in length and may have been predatory. Its bottom was covered with two rows of tough interlocking plates, while one row covered its top; its front few segments fused to form a "head." ''Spriggina'' affinity is currently unknown; it has been variously classified as an annelid worm, a rangeomorph-like frond, a variant of ''Charniodiscus'', a proarticulatan, or an arthropod perhaps related to the trilobites, or even an extinct phylum. Lack of known segmented legs or limbs, and glide reflection instead of symmetric segments, suggest an arthropod classification is unlikely despite some superficial resemblance. The genus ''Spriggina'' may have originally co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ivovicia
''Ivovicia'' is an extinct genus of proarticulates. This monotypic genus has only one species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...: ''Ivovicia rugulosa''. References Notes Budd, Graham E.; Jensen, Sören. The origin of the animals and a ‘Savannah’ hypothesis for early bilaterian evolution. Biological Reviews November 2015.Freeman, Gary. The rise of bilaterians. Historical Biology 2009 03.Sokolov, B.S.. The chronostratigraphic space of the lithosphere and the Vendian as a geohistorical subdivision of the Neoproterozoic. Russian Geology and Geophysics October 2011.Grazhdankin, Dmitriy. Patterns of Evolution of the Ediacaran Soft-Bodied Biota. Journal of Paleontology 2014 03.Retallack, Gregory J.. Ediacaran fossils in thin-section. Alcheringa: An Australasian Jou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaeaspinus
''Archaeaspinus fedonkini'' is an extinct proarticulatan organism from the Late Precambrian (Ediacaran) period. Background ''Archaeaspinus'' was discovered in Zimnii Bereg, the Winter Coast of the White Sea in Russia, by A. Yu. Ivantsov in 2001. Since then, numerous additional fossils have been attributed to the genus, mostly from that same type locality, but a small number from Flinders Ranges in South Australia as well.Mikhail A. Fodonkin, James G. Gehling, Kathleen Grey, Guy M. Narbonne, Patricia Vickers-Rich''The Rise of Animals, Evolution and Diversification of the Kingdom Animalia'' Johns Hopkins University Press, Baltimore, 2007 Originally called '' Archaeaspis''—a name already preoccupied by a redlichiid trilobite—in 2001 by Ivantsov, it was later recombined under its current name in 2007 by the same author. The type species ''A. fedonkini'' is the only species known to the genus. It appears in the fossil record between 571-551Ma. Description Like other genera w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andiva
''Andiva ivantsovi'' is a Vendian fossil, identified to be a bilaterian triploblastic animal in the Ediacaran phylum Proarticulata, known from the Winter Coast, White Sea, Russia. It was first discovered in 1977, and described as a new species in a new genus by Mikhail Fedonkin in 2002. It lived about 555 million years ago. Fossils of ''Andiva'' also occur in South Australia. All known fossils of ''Andiva'' are external molds. Description ''Andiva'' was between long and from wide, with a bilaterally symmetrical shape, larger on the anterior end and narrower at the posterior. The anterior part features a smooth "fringe" followed by a surface "covered by fine ribs and sutura", also described as a "quilt" with narrow, tightly packed chambers The symmetry of these ribs is a glide symmetry, that is, in which the corresponding segments on the left and right sides do not line up, but are staggered. This is a feature shared by other forms belonging to the proposed taxon Proarticulat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
