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Vendiamorpha

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Vendiamorpha
Paravendia janae, Vendia sokolovi,
V. rachiata
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: †Proarticulata
Class: †Vendiamorpha
Fedonkin, 1985
Families and genera

Vendiamorpha[1] 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 the body. This phenomenon is described as the symmetry of glide reflection. Transverse elements decrease in size from one end to the 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.[2][3][4] 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,[5][6] though, overwhelming evidence of them being proarticulatans have since lead researchers to discard this hypothesized relationship.[1][2]

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.[2][3]

Class Vendiamorpha currently includes only one Family Vendiidae (originally referred to as Vendomiidae as the type genus Vendomia,[7] before V. menneri was redescribed as a member of Dickinsonia[8]) that consist of species Vendia sokolovi, V. rachiata, Paravendia janae and possibly Karakhtia nessovi from Ediacaran (Vendian) rocks of the Arkhangelsk Region, Russia.[2][3][4][9]

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,[10] later as a Proarticulata,[1] then speculated as possibly a frond-like organism.[11] Current scientific consensus now recognizes the poorly preserved holoytype of Pseudovendia as a pseudofossil.[12][13]

See also

References

  1. ^ a b c 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.
  2. ^ a b c d Ivantsov, A.Y. (2001). "Vendia and Other Precambrian "Arthropods"". Paleontological Journal. 35 (4): 335–343.
  3. ^ a b c Ivantsov, A. Yu (2004). "New Proarticulata from the Vendian of the Arkhangel'sk Region" (PDF). Paleontological Journal. 38 (3): 247–253. Archived from the original (PDF) on 2007-09-27. Retrieved 2007-09-27.
  4. ^ a b 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.
  5. ^ 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)
  6. ^ Glaessner M. F., Wade M. (1971). "Praecambridium - a primitive arthropod". Lethaia. 4 (1): 71–77. doi:10.1111/j.1502-3931.1971.tb01280.x.
  7. ^ B. M. Keller and M. A. Fedonkin (1976). "New Records of Fossils in the Valdaian Group of the Precambrian on the Syuz'ma River" (PDF). Izv. Akad. Nauk SSSR, Ser. Geol. (in Russian). 3: 38–44. Archived from the original (PDF) on 2007-09-27. Retrieved 2007-09-27.
  8. ^ Ivantsov, A. Yu. (April 2007). "Small Vendian transversely Articulated fossils". Paleontological Journal. 41 (2): 113. doi:10.1134/S0031030107020013.
  9. ^ Ivantsov, A.Y.; Malakhovskaya, Y.E.; Serezhnikova, E.A. (2004). "Some Problematic Fossils from the Vendian of the Southeastern White Sea Region" (PDF). Paleontological Journal. 38 (1): 1–9. Archived from the original (PDF) on 2007-07-04. Retrieved 2007-03-08.
  10. ^ H. E. Boynton, T. D. Ford (1979). "Pseudovendia charnwoodensis — A new Precambrian arthropod from Charnwood Forest, Leicestershire". Mercian Geologist. 7: 175–177.
  11. ^ H. E. Boynton (2010). "Charnian Fossils in the Outwoods" (PDF). Mercian Geologist. 17 (3): 175–177.
  12. ^ 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
  13. ^ Liu, A. G.; McIlroy, D.; Antcliffe, J. B.; Brasier, M. D. (2010). "Effaced preservation in the Ediacara biota and its implications for the early macrofossil record". Palaeontology. 54 (3): 607–630. doi:10.1111/j.1475-4983.2010.01024.x.
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