| Vendiamorpha | |
|---|---|
 | |
| Paravendia janae, Vendia sokolovi, V. rachiata | |
Scientific classification  | |
| 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.
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]
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]
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". The discovery of cholesterol molecules in fossils of Dickinsonia lends support to the idea that Dickinsonia was an animal.
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.
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 3–5 centimetres (1.2–2.0 in) 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."
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.
Cephalonega stepanovi is a fossil organism from Ediacaran deposits of the Arkhangelsk Region, Russia. It was described by Mikhail A. Fedonkin in 1976
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.
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.
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.
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.
Proarticulata is a proposed phylum of extinct, 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.
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.
The "ivesheadiomorphs" are a group of fossilised structures known from Ediacaran localities in England and Newfoundland. They are considered to be taphomorphs, representing the poorly preserved biological remains of various contemporary taxa such as Charnia, Charniodiscus, Bradgatia, Primocandelabrum, Pectinifrons and others, that were effaced by partial decay by micro-organisms following death on the seafloor before burial by sediment.
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.
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.
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.
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.
Archaeaspinus fedonkini is an extinct proarticulatan organism from the Late Precambrian (Ediacaran) period.
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.
Ivovicia is an extinct genus of proarticulates. This monotypic genus has only one species: Ivovicia rugulosa.
| |||||||
| Vendiamorpha |
|  | |||||
| Dipleurozoa |
| ||||||
| Cephalozoa |
| ||||||
| Unclassified | |||||||
Part of the Ediacaran biota | |||||||
 | This Ediacaran biota-related article is a stub. You can help Wikipedia by expanding it. |