Proarticulata

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Proarticulata
Temporal range: Late Ediacaran, between 567–550  Ma
DickinsoniaCostata.jpg
Fossil of Dickinsonia costata
Spriggina Floundensi 4.png
Fossil of Spriggina
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Stem group: Bilateria
Phylum:† Proarticulata
Fedonkin, 1985
Class / Family

For more taxa, see text

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. [1] [2] The name comes from the Greek προ (pro-) = "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 [3] and currently many other Proarticulata are described (see list). [4] [5]

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 isomers occupy only half the width of their bodies, and are organized in an alternating pattern along the longitudinal axis of their bodies. [5] In other words, one side is not the direct mirror image of its opposite ( chirality ). Opposite isomers of left and right side are located with displacement of half of their width. This phenomenon is described as the symmetry of gliding reflection. [6] [7] Some recent research suggests that some proarticulatans like Dickinsonia have genuine segments, and the isomerism is superficial and due to taphonomic distortion. [8] However, other researchers dispute this. [9] [10] Displacement of left-right axis is known in bilaterians, notably lancelets. [11] [12]

Morphology

Examples of the classes Proarticulata, including reconstructions of Vendia sokolovi, Dickinsonia costata and Yorgia waggoneri. Proarticulata Classes.jpg
Examples of the classes Proarticulata, including reconstructions of Vendia sokolovi, Dickinsonia costata and Yorgia waggoneri.

Vendiamorpha

The body is completely segmented, with all isomers curved towards the posterior, and the first isomer is normally much larger than the rest. The first two isomers at the anterior dorsal end are partly fused. (e.g., Vendia , Paravendia and Karakhtia ). [6] [13] [14] [15]

Cephalozoa

These proarticulatans are incompletely segmented, as the anterior zone is free of isomers, often making a "hairband" like appearance (example cephalozoans include Yorgia , Praecambridium , Andiva , Archaeaspinus , Ivovicia , Podolimirus , Tamga , Spriggina , Marywadea and Cyanorus ). [6] [13] [15] [16] Some cephalozoans from the family Yorgiidae demonstrate pronounced asymmetry of the left and right parts of the body. For instance, Yorgia’s initial right isomer is the only one which spreads far towards the left side of the body. Archaeaspinus has an unpaired anterior lobe confined by the furrow to the left side only. [6] [7] [15]

Artist's reconstruction of Cephalonega stepanovi. Cephalonega stepanovi.jpg
Artist's reconstruction of Cephalonega stepanovi.
Artist's reconstruction of Lossinia feeding on surface algae. Lossinia lissetski.jpg
Artist's reconstruction of Lossinia feeding on surface algae.

In Cephalonega stepanovi and Tamga hamulifera the zone containing the isomers is encircled by a peripheral, undivided zone. [16] The Cephalonega 's isomers are connected to each other, forming a body resembling a rubber raft; the Tamga 's isomers are separated from each other, and do not touch.

In Lossinia , the center undivided region has no visible isomers, instead having the lobe-like isomers emanate from the periphery of the undivided region as "transverse articulations." [16]

Dipleurozoa

The dipleurozoan body is subradial, divided by isomers entirely (e.g., Dickinsonia and Phyllozoon ). Dickinsonia juveniles show undivided anterior areas but these regions were reduced in the course of ontogeny, and in the adult stages Dickinsonia-like proarticulates changed so radically that they became almost indistinguishable from isomers. [13] [16] [18]

List of Proarticulata

Andiva ivantsovi.jpg
Andiva ivantsovi
DickinsoniaCostata3.png
Dickinsonia costata
Spriggina Floundensi 4.png
Spriggina floundersi
Ovatoscutum concentricium cropped.png
Ovatoscutum concentricum
Yorgia.jpg
Yorgia waggoneri
Tamga hamulifera.JPG
Tamga hamulifera

Body fossils

A. parva Fedonkin, 1980
A. ivantsovi Fedonkin, 2002
A. fedonkini Ivantsov, 2001
C. stepanovi (Fedonkin, 1976) [16] [22]
C. bilobatum Wade, 1971
C. singularis Ivantsov, 2004
D. costata Sprigg, 1947
D. menneri Keller 1976 [16] (=Vendomia menneri Keller 1976 [22] )
D. tenuis Glaessner & Wade, 1966
I. rugulosa Ivantsov, 2007
K. nessovi Ivantsov, 2004
L. lissetskii Ivantsov, 2007
M. ovata Glaessner & Wade, 1966
O. concentricum Glaessner & Wade, 1966
P. janae Ivantsov, 2001 (=Vendia janae Ivantsov, 2001)
P. mirus Fedonkin, 1983 (Valdainia plumosa Fedonkin, 1983)
P. siggilum Glaessner & Wade, 1966
S. floundersi Glaessner, 1958
T. hamulifera Ivantsov, 2007
V. sokolovi Keller, 1969
V. rachiata Ivantsov, 2004
W. aitkeni Narbonne, 1994 [24]
Y. waggoneri Ivantsov, 1999

Trace fossils

E. axiferus Ivantsov, 2002.
E. waggoneris Ivantsov, 2011. This is a trace of Yorgia waggoneri
E. costatus Ivantsov, 2011. This is a trace of Dickinsonia costata
P. hanseni Jenkins & Gehling, 1978

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. 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>Kimberella</i> Primitive Mollusc-like organism

Kimberella is an extinct genus of bilaterian known only from rocks of the Ediacaran period. The slug-like organism fed by scratching the microbial surface on which it dwelt in a manner similar to the gastropods, although its affinity with this group is contentious.

<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.

<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.

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

Trilobozoa is a phylum of extinct, sessile animals that were originally classified into the Cnidaria. The basic body plan of trilobozoans is often a tri-radial or radial sphere-shaped form with lobes radiating from its centre. Fossils of trilobozoans are restricted to marine strata of the Late Ediacaran period.

<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>Ovatoscutum</i> Extinct species of enigmatic organism

Ovatoscutum concentricum is one of many enigmatic organisms known from the Ediacaran deposits of the Flinders Ranges, Australia, and the White Sea area in Russia, dating around 555 Ma.

<span class="mw-page-title-main">Vendiamorpha</span> Extinct class of simple animals

Vendiamorpha is a class of extinct animals within the Ediacaran phylum Proarticulata.

<i>Tamga hamulifera</i>

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>

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. ↑ Maslov AV, Podkovyrov VN, Grazhdankin DV, Kolesnikov AV (2018). "Upper Vendian in the east, northeast and north of East European Platform: Depositional processes and biotic evolution". Litosfera. 18 (4): 520–542. doi: 10.24930/1681-9004-2018-18-4-520-542 .
  2. ↑ Kolesnikov AV, Liu AG, Danelian T, Grazhdankin DV (2018). "A reassessment of the problematic Ediacaran genus Orbisiana Sokolov 1976". Precambrian Research. 316: 197–205. Bibcode:2018PreR..316..197K. doi:10.1016/j.precamres.2018.08.011. S2CID   134213721.
  3. ↑ Fedonkin MA (1985). "Systematic Description of Vendian Metazoa". In Sokolov BS, Iwanowski AB (eds.). Vendian System: Historical–Geological and Paleontological Foundation. Vol. 1: Paleontology. Moscow: Nauka. pp. 70–106.
  4. ↑ Fedonkin MA (31 March 2003). "The origin of the Metazoa in the light of the Proterozoic fossil record" (PDF). Paleontological Research. 7 (1): 9–41. doi:10.2517/prpsj.7.9. S2CID   55178329.
  5. 1 2 Ivantsov AY, Fedonkin MA, Nagovitsyn AL, Zakrevskaya ZA (2019). "Cephalonega, a new generic name, and the system of Vendian Proarticulata". Paleontological Journal. 53 (5): 447–454. doi:10.1134/S0031030119050046. S2CID   203853224.
  6. 1 2 3 4 5 6 7 Ivantsov, A.Yu. (2001). "Vendia and other precambrian "Arthropods"". Paleontological Journal. 35 (4): 335–343.
  7. 1 2 3 Ivantsov, A.Yu. (1999). "A new Dickinsoniid from the upper Vendian of the White Sea Winter Coast (Russia, Arkhangelsk region)". Paleontological Journal. 33 (3): 233–241.
  8. ↑ Dunn FS, Liu AG, Donoghue PC (May 2018). "Ediacaran developmental biology". Biological Reviews of the Cambridge Philosophical Society. 93 (2): 914–932. doi:10.1111/brv.12379. PMC   5947158 . PMID   29105292.
  9. ↑ Ivantsov AY, Zakrevskaya MA, Nagovitsyn AL (June 2019). "Morphology of integuments of the Precambrian animals, Proarticulata". Invertebrate Zoology. 16 (1): 19–26. doi: 10.15298/invertzool.16.1.03 .
  10. ↑ Ivantsov Y, Fedonkin MA, Nagovitsyn AL, Zakrevskaya MA (September 2019). "Cephalonega, A New Generic Name, and the System of Vendian Proarticulata". Paleontological Journal. 53 (5): 447–454. doi:10.1134/s0031030119050046. S2CID   203853224.
  11. ↑ Blum M, Feistel K, Thumberger T, Schweickert A (April 2014). "The evolution and conservation of left-right patterning mechanisms". Development. 141 (8): 1603–13. doi: 10.1242/dev.100560 . PMID   24715452.
  12. ↑ Soukup V (2017). "Left-right asymmetry specification in amphioxus: review and prospects". The International Journal of Developmental Biology. 61 (10–11–12): 611–620. doi: 10.1387/ijdb.170251vs . PMID   29319110.
  13. 1 2 3 4 5 6 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.
  14. ↑ 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 2007-07-04.
  15. 1 2 3 Ivantsov, A.Yu. (2004). Vendian animals in the phylum Proarticulata (PDF). The Rise and Fall of the Vendian Biota. Prato, Italy. p. 52. IGSP Project 493.
  16. 1 2 3 4 5 6 7 8 9 10 Ivantsov, A.Yu. (April 2007). "Small Vendian transversely articulated fossils". Paleontological Journal. 41 (2): 113–122. doi:10.1134/S0031030107020013. S2CID   86636748.
  17. ↑ illustration (c) Stanton F. Fink
  18. 1 2 Ivantsov, A.Yu.; Malakhovskaya, Y.E. (2002). "Giant traces of Vendian animals" (PDF). Doklady Earth Sciences. 385 (6): 618–622. Archived from the original (PDF) on 2007-07-04.
  19. ↑ Ivantsov AY (December 2010). "Paleontological evidence for the supposed precambrian occurrence of mollusks". Paleontological Journal. 40 (12): 1552–1559. doi:10.1134/S0031030110120105. S2CID   86523806.
  20. ↑ Fedonkin MA (2002). "Andiva ivantsovi gen. et sp. n. and related carapace‐bearing Ediacaran fossils from the Vendian of the Winter Coast, White Sea, Russia". Italian Journal of Zoology. 69 (2): 175–181. doi: 10.1080/11250000209356456 . S2CID   85352552.
  21. ↑ Ivantsov AY, Fedonkin MA, Nagovitsyn AL, Zakrevskaya MA (2019). "Cephalonega, a new generic name, and the system of Vendian Proarticulata". Paleontological Journal. 53 (5): 447–454. doi:10.1134/S0031030119050046. S2CID   203853224.
  22. 1 2 Keller BM, Fedonkin MA (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 2007-09-27.
  23. ↑ Dzik, J.; Martyshyn, A. (2015). "Taphonomy of the Ediacaran Podolimirus and associated dipleurozoans from the Vendian of Ukraine". Precambrian Research. 269: 139–146. doi:10.1016/j.precamres.2015.08.015.
  24. ↑ Narbonne GM (May 1994). "New Ediacaran fossils from the Mackenzie Mountains, Northwestern Canada". Journal of Paleontology. 63 (3): 411–416. doi:10.1017/S0022336000025816. JSTOR   1306192. S2CID   133215767.
  25. ↑ Ivantsov AY (May 2011). "Feeding traces of Proarticulata — the Vendian metazoa". Paleontological Journal. 45 (3): 237–248. doi:10.1134/S0031030111030063. S2CID   128741869.
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