Vendiamorpha

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Vendiamorpha
Temporal range: Late Ediacaran, between 567–550  Ma
Vendia rachiata.JPG
Paravendia janae, Vendia sokolovi,
V. rachiata
Scientific classification OOjs UI icon edit-ltr.svg
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.

Contents

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.

Description

Karakhtia Karakhtia nessovi.jpg
Karakhtia

The phenomenon of left-right alternating segments is called glide reflection symmetry, and is a diagnostic feature of proarticulatans. 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 have originally considered them to be ancestral or related to arthropods, [5] [6] though, overwhelming evidence of them being proarticulatans have since led researchers to discard this hypothetical 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 in Russia. [2] [3] [4] [9]

Name

The clade name Pseudovendia refers to the resemblances to a fossil imprint described as Vendia sokolovi. Originally, that fossil was interpreted as an arthropod, [10] later as a proarticulatan, [1] then conjectured as possibly a frond-like organism. [11]

Current scientific consensus now recognizes the poorly preserved holotype of Pseudovendia as a pseudofossil. [12] [13]

See also

Related Research Articles

<i>Dickinsonia</i> Extinct genus of early animals

Dickinsonia is a genus of extinct organism, most likely an animal, that lived during the late Ediacaran period in what is now Australia, China, Russia, and Ukraine. It is one of the best known members of the Ediacaran biota. The individual Dickinsonia typically resembles a bilaterally symmetrical ribbed oval. Its affinities are presently unknown; its mode of growth has been considered consistent with a stem-group bilaterian affinity, though various other affinities have been proposed. It lived during the late Ediacaran. The discovery of cholesterol molecules in fossils of Dickinsonia lends support to the idea that Dickinsonia was an animal, though these results have been questioned.

<i>Tribrachidium</i> Extinct genus of invertebrates

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.

<i>Yorgia</i> Extinct proarticulate animal

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 25 cm (9.8 in). It is classified within the extinct animal phylum Proarticulata.

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.

<i>Cephalonega</i> Extinct genus of invertebrates

Cephalonega stepanovi is a fossil organism from Ediacaran deposits of the Arkhangelsk Region, Russia. It was described by Mikhail A. Fedonkin in 1976

<i>Vendia</i> Fossil taxon

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.

<i>Praecambridium</i> Extinct genus of marine animals

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.

<i>Albumares</i> Extinct genus of soft-bodied Trilobozoan

Albumares brunsae is a tri-radially symmetrical fossil animal that lived in the late Ediacaran seafloor. It is a member of the extinct group Trilobozoa.

<i>Anfesta</i> Extinct genus of marine invertebrates

Anfesta stankovskii is a tri-radially symmetrical fossil animal that lived in the late Ediacaran (Vendian) seafloor. It is a member of the extinct group Trilobozoa.

<span class="mw-page-title-main">Proarticulata</span> Extinct phylum of animals

Proarticulata is a proposed phylum of extinct, near-bilaterally symmetrical animals known from fossils found in the Ediacaran (Vendian) marine deposits, and dates to approximately 567 to 550 million years ago. The name comes from the Greek προ = "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.

<i>Tamga hamulifera</i> Extinct species of Cambrian organism

Tamga hamulifera is a disk-shaped fossil from Precambrian strata of the White Sea area, in Russia, the only member of the genus Tamga.

<span class="mw-page-title-main">Isomer (Proarticulata)</span> Element in fossils

Isomer 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.

<i>Epibaion</i>

Epibaion is a trace fossil imprint of the Ediacaran animals of the phylum Proarticulata, which became extinct in the Precambrian. Imprints often occurring in chains, that is interpreted as a feeding trace; some chains terminate in a body fossil, allowing their maker to be identified. Several specimens are known; E. waggoneris was produced by Yorgia waggoneri; E. costatus by Dickinsonia costata, and E. axiferus, the type species, has as yet not been found with a trace-maker. It is proposed that the Australian fossil Phyllozoon is also a feeding trace of Proarticulata.

<i>Andiva</i> Vendian fossil

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.

<i>Lossinia</i> Extinct species of marine organism

Lossinia lissetskii is a fossil marine organism from Precambrian strata of the White Sea area, in Russia. L. lissetskii is a member of the extinct phylum Proarticulata.

<i>Cyanorus</i> Genus of Precambrian organisms

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.

<i>Archaeaspinus fedonkini</i> Extinct species of animal

Archaeaspinus fedonkini is an extinct proarticulatan organism from the Late Precambrian (Ediacaran) period.

<span class="mw-page-title-main">Cephalozoa</span> Extinct class of marine animals

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.

<i>Ivovicia</i> Genus of proarticulate

Ivovicia is an extinct genus of proarticulates. This monotypic genus has only one species: Ivovicia rugulosa.The genus is named after the Ivovik creek, near the place where the specimen was found.

References

  1. 1 2 3 Fedonkin, M.A. (1985). "Systematic description of Vendian metazoa". In Sokolov, B.S.; Iwanowski, A.B. (eds.). Vendian System: Historical–Geological and Paleontological Foundation. Vol. 1: Paleontology. Moscow, RU: Nauka. pp. 70–106.
  2. 1 2 3 4 Ivantsov, A.Yu (2001). "Vendia and Other Precambrian "Arthropods"". Paleontological Journal. 35 (4): 335–343.
  3. 1 2 3 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 27 September 2007. Retrieved 27 September 2007.
  4. 1 2 Ivantsov, A.Yu. (2004). Vendian animals in the phylum Proarticulata (PDF). The Rise and Fall of the Vendian Biota (abstract). Prato, Italy. p. 52. IGSP Project 493.
  5. ↑ Menner, V.V. (1963). "The other problematical organic remains". Stratigraphy of the USSR: Upper Precambrian (in Russian). Moscow, RU: Gos. Nauchno-Tekh. Izd. pp. 504–507.
  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. ↑ Keller, B.M.; Fedonkin, M.A. (1976). "New records of fossils in the Valdaian group of the precambrian on the Syuz'ma River" (PDF). Izvestiya Akademii Nauk SSR. Seriya Geologicheskaya (in Russian). 3: 38–44. Archived from the original (PDF) on 27 September 2007. Retrieved 27 September 2007.
  8. ↑ Ivantsov, A.Yu. (April 2007). "Small Vendian transversely articulated fossils". Paleontological Journal. 41 (2): 113. doi:10.1134/S0031030107020013.
  9. ↑ Ivantsov, A.Yu.; Malakhovskaya, Y.E.; Serezhnikova, E.A. (2004). "Some problematic fossils from the Vendian of the south-eastern White Sea region" (PDF). Paleontological Journal. 38 (1): 1–9. Archived from the original (PDF) on 4 July 2007. Retrieved 8 March 2007.
  10. ↑ Boynton, H.E.; Ford, T.D. (1979). "Pseudovendia charnwoodensis — A new Precambrian arthropod from Charnwood Forest, Leicestershire". Mercian Geologist. 7: 175–177.
  11. ↑ Boynton, H.E. (2010). "Charnian fossils in the outwoods" (PDF). Mercian Geologist. 17 (3): 175–177.
  12. ↑ Grazhdankin, D.V. (2007). Charnwood biota as seen from arctic Russia – Ediacarans and their environments (PDF). Leicester’s fossil celebrity: Charnia and the evolution of early life (abstract). Leicester, UK: University of Leicester. pp. 15–16.
  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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