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Vendiamorpha〔M. A. Fedonkin (1985). "Systematic Description of Vendian Metazoa". In Sokolov, B. S. and Iwanowski, A. B., eds., "Vendian System: Historical–Geological and Paleontological Foundation, Vol. 1: Paleontology". Moscow: Nauka, pp. 70–106.〕 is a class of extinct animals within the Ediacaran phylum Proarticulata. The typical vendiamorph had an oval-shaped or round-shaped body divided completely into segmented isomers, that were arranged alternately in two rows with reference to the longitudinal axis of body. This phenomenon is described as ''the symmetry of glide reflection''. Transverse elements decrease in size from one end to other and are inclined in the same direction. The larger isomers cover the smaller ones externally and the first isomer is much larger than the rest.〔〔〔 Typically, the first few, or largest isomers are fused together to form a headshield-like structure, leading some researchers to originally consider them ancestral or related to arthropods,〔V. V. Menner. (1963). "The Other Problematical Organic Remains". In: "Stratigraphy of the USSR: Upper Precambrian". Moscow: Gos. Nauchno-Tekh. Izd., 504-507. (In Russian)〕 though, overwhelming evidence of them being proarticulatans have since lead researchers to discard this hypothesized relationship.〔〔 Some vendiamorphs, e.g., ''Vendia'' and ''Paravendia'', supposedly demonstrate a digestive-distributive system consisting of a simple axial tube and lateral appendages, with one lateral appendage corresponding to one isomer.〔〔 Class Vendiamorpha currently includes only one Family Vendiidae (originally referred to as Vendomiidae as the type genus ''Vendomia'', before ''V. menneri'' was redescribed as a member of ''Dickinsonia'') that consist of species ''Vendia sokolovi'', ''V. rachiata'', ''Paravendia janae'' and ''Karakhtia nessovi'' from Ediacaran (Vendian) rocks of the Arkhangelsk Region, Russia.〔Ivantsov, A.Y. (2004) ("Vendian Animals in the Phylum Proarticulata" ). The Rise and Fall of the Vendian Biota. IGSP Project 493. Abstracts. Prato, Italy, p. 52.〕 ''Pseudovendia'', its name refers to the some resemblance of this fossil with imprint of the ''Vendia sokolovi''. Originally, this fossil was interpreted as an arthropod, later as a Proarticulata,〔 then speculated as possibly a frond-like organism. Current scientific consensus now recognizes the poorly preserved holoytype of ''Pseudovendia'' as a pseudofossil.〔Grazhdankin, 2007. "Leicester’s fossil celebrity: ''Charnia'' and the evolution of early life" (pages 15-16) http://www.le.ac.uk/gl/charnia2007/AbstractBooklet2007r.pdf〕 ==See also== List of Ediacaran genera 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Vendiamorpha」の詳細全文を読む スポンサード リンク
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