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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] |
Archaeaspinus Fedonkini
''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 wi ... [...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] |
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] |
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] |
Andiva Ivantsovi
''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] |
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] |
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] |
Yorgia Sketch
''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] |
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] |
Yorgia Waggoneri
''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] |
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] |
Praecambridium Sigillum
''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] |
