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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] |
Andiva Sketch
''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 Proarticulata ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proarticulata
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 isome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalozoa
Cephalozoa are an extinct class of primitive segmented marine organisms within the Phylum Proarticulata from the Ediacaran period. They possessed bilateral symmetry and were characterized by a thin, rounded body. Description Unlike the other classes of proarticulates, the segmentation of the body is not complete and shows a "head" with fine distribution channels. Some species of the Yorgiidae family also show some asymmetry.Ivantsov, A. Y. (2004"Vendian Animals in the Phylum Proarticulata" The Rise and Fall of the Vendian Biota. IGSP Project 493. Abstracts. Prato, Italy, . They were discovered in Russia near the White Sea in the Arkhangelsk region, where they lived during the Ediacaran, approximately 635 to 540 Ma (millions of years ago). Taxonomy Cephalozoa includes the families Yorgiidae and Sprigginidae: Yorgiidae *† ''Archaeaspinus'' Ivantsov, 2007 (synonym of ''Archaeaspis'') **† ''Archaeaspinus fedonkini'' Ivantsov, 2001 *† ''Yorgia'' Ivantsov, 1999 **† ''Yorgi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ovatoscutum
''Ovatoscutum concentricum'' is one of many enigmatic organisms known from the Ediacaran deposits of the Flinders Ranges, Australia, and the White Sea area in Russia, dating around 555 Ma. Etymology The generic name ''Ovatoscutum'' is derived from the Latin ''ovatus'' (oval) and ''scutum'' (shield). Description This fossil has the form of a rounded shield, enclosing strongly concentric corrugations or ribs, which weaken adjacent to a triangular neckline. A suture-like zone extends through the center from the apex of the neckline towards the opposite margin. The ribs become wider towards the periphery. The symmetry of these ribs exhibits glide reflection (opposite isometry); that is, the corresponding segments on the left and right sides do not line up, but are offset. Affinity ''Ovatoscutum'' was first described by Martin Glaessner and Mary Wade in 1966, and this team tentatively interpreted it as a chondrophoran pneumatophore. This notion was based on morphologies apparently ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dickinsonia
''Dickinsonia'' is an extinct genus of basal animal that lived during the late Ediacaran period in what is now Australia, China, Russia and Ukraine. The individual ''Dickinsonia'' typically resembles a bilaterally symmetrical ribbed oval. Its affinities are presently unknown; its mode of growth is consistent with a stem-group bilaterian affinity, though some have suggested that it belongs to the fungi, or even an "extinct kingdom". It lived during the late Ediacaran (part of Precambrian). The discovery of cholesterol molecules in fossils of ''Dickinsonia'' lends support to the idea that ''Dickinsonia'' was an animal. Description ''Dickinsonia'' fossils are known only in the form of imprints and casts in sandstone beds. The specimens found range from a few millimetres to about in length, and from a fraction of a millimetre to a few millimetres thick. They are nearly bilaterally symmetric, segmented, round or oval in outline, slightly expanded to one end (i.e. egg-shaped out ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kimberella
''Kimberella'' is an extinct genus of bilaterian known only from rocks of the Ediacaran period. The slug-like organism fed by scratching the microbial surface on which it dwelt in a manner similar to the gastropods, although its affinity with this group is contentious. Specimens were first found in Australia's Ediacara Hills, but recent research has concentrated on the numerous finds near the White Sea in Russia, which cover an interval of time from . As with many fossils from this time, its evolutionary relationships to other organisms are hotly debated. Paleontologists initially classified ''Kimberella'' as a type of Cubozoan, but, since 1997, features of its anatomy and its association with scratch marks resembling those made by a radula have been interpreted as signs that it may have been a mollusc. Although some paleontologists dispute its classification as a mollusc, it is generally accepted as being at least a bilaterian. The classification of ''Kimberella'' is imp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vendia
''Vendia'' is a genus of oval-shaped, Ediacaran fossils ranging from 4.5 to 12.5 mm long. The body is completely segmented into isomers, which are arranged alternately in two rows longitudinal to the axis of the body. The larger isomers cover the smaller ones externally but the posterior ends of all the isomers remain free. The transverse elements decrease in size from anterior to posterior and are all inclined in the same direction. The fossil bears a depression along a body that is interpreted as a digestive-distributive system that consists of a simple axial tube and short lateral appendages located along the borders between the isomers. Except for the first isomer of ''Vendia rachiata'', all the isomers have one lateral appendage. The first species, ''V. sokolovi'', was originally found in a core from a Yarensk borehole in the south of Arkhangelsk Oblast of Russia in beginning of the 1960s V. V. Menner. (1963). "The Other Problematical Organic Remains". In: "Stratigrap ... [...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] |
Praecambridium
''Praecambridium sigillum'' is an extinct organism that superficially resembles a segmented trilobite-like arthropod. It was originally described as being a trilobite-like arthropod, though the majority of experts now place it within the Proarticulata as a close relative of the much larger ''Yorgia''. It is from the Late Ediacaran deposit of Ediacara Hills, Australia, about 555 million years ago. On average, ''P. sigillum'' had at least 5 pairs of segments, with each unit becoming progressively larger as they approach the cephalon-like head. Etymology The generic name is a compound word, with the Latin prefix ''prae'' "before" and a reference to the Cambrian mollusc genus '' Cambridium'', in reference to how the appearance of the various segments are reminiscent of the muscle-scars on the inner surface of the shells of '' Cambridium''. The specific name is from Latin ''sigillum'' "a sigil". Classification and interpretations Originally, Runnegar and M.A. Fedokin (1992) suggested ... [...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] |
Carapace
A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron. Crustaceans In crustaceans, the carapace functions as a protective cover over the cephalothorax (i.e., the fused head and thorax, as distinct from the abdomen behind). Where it projects forward beyond the eyes, this projection is called a rostrum (anatomy), rostrum. The carapace is Calcification, calcified to varying degrees in different crustaceans. Zooplankton within the phylum Crustacea also have a carapace. These include Cladocera, ostracods, and Isopoda, isopods, but isopods only have a developed "cephalic shield" carapace covering the head. Arachnids In arachnids, the carapace is formed by the fusion of prosomal tergites into a single Plate (animal anatomy), plate which carries the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tribrachidium
''Tribrachidium heraldicum'' is a tri-radially symmetric fossil animal that lived in the late Ediacaran (Vendian) seas. In life, it was hemispherical in form. ''T. heraldicum'' is the best known member of the extinct group Trilobozoa. Etymology The generic name ''Tribrachidium'' is derived from combination of the grc, τρία (, "three") + la, brachium ("arm") + diminutive suffix . The specific name ''T. heraldicum'' references the similarity of the pattern of this fossil with the well-known heraldic triskelion design, such as the coat of arms of the Isle of Man. Occurrence ''Tribrachidium'' fossils were first discovered in the Ediacara Member of the Rawnslay Quartzite, Flinders Ranges in South Australia. This fossil is also known from the Mogilev Formation in the Dniester River Basin, Podolia, Ukraine and from the Verkhovka, Zimnegory and Yorga Formations in the White Sea area of the Arkhangelsk Region, Russia. Description ''T. heraldicum'' is preserved as negative impressio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
