Tribrachidium

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Tribrachidium heraldicum
Temporal range: Ediacaran, 558–555  Ma
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Tribrachidium.jpg
Fossil of Tribrachidium heraldicum
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum:† Trilobozoa
Family:† Tribrachididae
Runnegar, 1992
Genus:† Tribrachidium
Glaessner, 1959
Species:
†T. heraldicum
Binomial name
†Tribrachidium heraldicum
Glaessner, 1959
Synonyms

PomoriaFedonkin, 1980 [1] [2]

  • P. corolliformisFedonkin, 1980

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.[ citation needed ]

Contents

Etymology

The generic name Tribrachidium is derived from combination of the Ancient Greek : τρία (tria, "three") + Latin : brachium ("arm") + diminutive suffix -idium. The specific name T. heraldicum references the similarity of the pattern of this fossil with the well-known heraldic triskelion design, such as the coat of arms of the Isle of Man. [3]

Occurrence

Tribrachidium fossils were first discovered in the Ediacara Member of the Rawnslay Quartzite, Flinders Ranges in South Australia. [3] [4] This fossil is also known from the Mogilev Formation in the Dniester River Basin, Podolia, Ukraine [5] and from the Verkhovka, Zimnegory and Yorga formations in the White Sea area of the Arkhangelsk Region, Russia. [6] [7] This fossil is also known from the Sonia Formation of Marwar Supergroup near Jodhpur, India. [8]

Description

T. heraldicum is preserved as negative impressions on the base of sandstone beds. These fossils have a circular, three-lobe form, with straight or trefoil-like edges; they are usually covered by numerous radial branched furrows. The central part of the fossil has three hooked ridges ("arms"). The lobes are twisted into weak spirals. [9]

The diameter of specimens ranges from 3 to 40 millimetres (0.3 to 4.0 cm). [10] Its meter-scale distribution was found to be variable occurring both as solitary individuals and in groups. [11]

Feeding Method

In a 2015 study, Rahman et al. proposed that Tribrachidium heraldicum used a rare 'gravity settling' mode of suspension feeding based on computational fluid dynamics simulations, which showed that water flow was directed passively by the arms, funneling it towards three depressions (‘apical pits’) where water flow slowed down so that food particles would fall out of suspension. [12]

Reconstruction and affinity

Reconstruction of Tribrachidium and other organisms: Tribrachidium heraldicum (top); Wigwamiella enigmatica,a taphomorph of aspidella (left); and Rugoconites enigmatica (right). Tribrachidium heraldicum e.JPG
Reconstruction of Tribrachidium and other organisms: Tribrachidium heraldicum (top); Wigwamiella enigmatica,a taphomorph of aspidella (left); and Rugoconites enigmatica (right).

Tribrachidium was originally described by Martin Glaessner as a problematic organism, one that is excluded from all known major groups of animals by its tri-radial symmetry. However, Tribrachidium's superficial resemblance to edrioasteroid echinoderms was well known to researchers and discussed. [3] [4] Later, Glaessner rejected any putative affinities of this animal with any known phyla, leaving the status of its taxonomy uncertain. [13] Originally, the various structures on the poorly preserved Australian specimens were interpreted as tentacles, peculiar arms and mouth, [4] but later this interpretation was rejected. Its mode of locomotion in life also remains unknown.[ citation needed ]

Pomoria Corolliformis was once thought to be a Cnidarian polyp, although it has been disproven as instead being a poorly preserved Tribrachidium. Pomoria corolliformis.jpg
Pomoria Corolliformis was once thought to be a Cnidarian polyp, although it has been disproven as instead being a poorly preserved Tribrachidium.

With the discovery of the closely related Albumares and Anfesta , along with the discoveries of much better-preserved Russian specimens, Mikhail Fedonkin proposed for these animals the new taxon, Trilobozoa – an extinct group of tri-radially symmetrical coelenterate-grade animals. [14] [15] Originally, Trilobozoa was erected as a separate class in the phylum Coelenterata, but after Coelenterata was divided into separate phyla Cnidaria and Ctenophora, the Trilobozoa was transferred to the rank of phylum. [16]

M. Fedonkin has shown that the fossil of Tribrachidium is an imprint of the upper side of the animal's body, with some elements of its external and internal anatomy. The radial furrows on the fossil are radial grooves on the surface of the living animal, while the three hooked ridges in central part of the fossil are imprints of cavities within the body. [14] Tribrachidium was a soft-bodied benthic organism that temporarily attached (but did not accrete) to the substrate of its habitat (microbial mats). [9]

See also

Related Research Articles

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

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<span class="mw-page-title-main">Vendobionta</span> Group of extinct creatures that were part of the Ediacaran biota

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<i>Yorgia</i> Extinct proarticulate animal

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<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>Rangea</i> Fossil taxon

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<i>Parvancorina</i> Genus of fossil arnimal

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

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<i>Bomakellia</i> Ediacaran fossil organism

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

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

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<span class="mw-page-title-main">Ediacaran biota</span> Life of the Ediacaran period

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

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

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<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>Rugoconites</i> Extinct genus of invertebrates

Rugoconites is a genus of Ediacaran biota found as fossils in the form of a circular or oval-like impression preserved in high relief, six or more centimeters in diameter. The fossils are surrounded by frills that have been interpreted as sets of tentacles. The bifurcating radial ribs, spreading from a central dome, serve to distinguish this genus from the sponge Palaeophragmodictya, and may represent the channels of the gastrovascular system. Fossils of Rugoconites have been interpreted as early sponges, although this is countered by Sepkoski et al. (2002), who interpreted the organism as a free-swimming jellyfish-like cnidarian; similar to Ovatoscutum. However, the fossil is consistently preserved as a neat circular form and its general morphology does not vary, therefore a benthic and perhaps slow-moving or sessile lifestyle is more likely. Ivantstov & Fedonkin (2002), suggest that Rugoconites may possess tri-radial symmetry and be a member of the Trilobozoa.

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

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<span class="mw-page-title-main">Petalonamae</span> Proposed extinct group of animals

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<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.

References

  1. ↑ Fedonkin, M. A. (1980). "New representative of the Precambrian coelenterates in the northern Russian platform". Paleontologicheskii Zhurnal. 5: 7–15.
  2. ↑ Ivantsov, A. Yu.; Zakrevskaya, M. A. (2021). "Trilobozoa, Precambrian Tri-Radial Organisms". Paleontological Journal. 55 (7): 727–741. Bibcode:2021PalJ...55..727I. doi:10.1134/S0031030121070066. S2CID   245330736.
  3. 1 2 3 Glaessner, M.F.; Daily, B. (1959). "The geology and Late Precambrian fauna of the Ediacara fossil reserve" (PDF). Records of the South Australian Museum. 13 (3): 369–401.
  4. 1 2 3 Glaessner, M.F.; Wade, M. (1966). "The late Precambrian fossils from Ediacara, South Australia" (PDF). Palaeontology. 9 (4): 599.
  5. ↑ Fedonkin, M. A. (1983). "Non-skeletal fauna of Podoloia, Dniester River valley". In Velikanov, V. A.; Asse]eva, E. A.; Fedonkin, M. A. (eds.). The Vendian of the Ukraine (in Russian). Kiev: Naukova Dumka. pp. 128–139.
  6. ↑ Fedonkin M.A. (1978). "New locality of non-skeletal Metazoa in the Vendian of Whinter Coast". Doklady Akademii Nauk SSSR (in Russian). 239 (6): 1423–1426.
  7. ↑ Fedonkin M. A.; Gehling J. G.; Grey K.; Narbonne G. M. & Vickers-Rich P. (2007). The Rise of Animals. Evolution and Diversification of the Kingdom Animalia. Johns Hopkins University Press. p. 326. ISBN   978-0-8018-8679-9.
  8. ↑ Parihar, V.S.; Hukmaram; Kumar, Pawan; Harsh, Anshul (25 February 2023). "Trilobozoan (Tribrachidium and Albumares) Ediacaran organisms from Marwar Supergroup, Western India" (PDF). Current Science. 124 (4): 485–490. doi:10.18520/cs/v124/i4/485-490 (inactive 1 November 2024).{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link)
  9. 1 2 Ivantsov, A. Yu.; Leonov M. V. (2009). The imprints of Vendian animals - unique paleontological objects of the Arkhangelsk region (in Russian). Arkhangelsk. p. 16. ISBN   978-5-903625-04-8.{{cite book}}: CS1 maint: location missing publisher (link)
  10. ↑ "Tribrachidium". www.Ediacaran.org. Retrieved 4 June 2021.
  11. ↑ Boan, Phillip C.; Evans, Scott D.; Hall, Christine M. S.; Droser, Mary L. (13 March 2023). "Spatial distributions of Tribrachidium, Rugoconites, and Obamus from the Ediacara Member (Rawnsley Quartzite), South Australia" . Paleobiology. 49 (4): 601–620. Bibcode:2023Pbio...49..601B. doi:10.1017/pab.2023.9. ISSN   0094-8373. S2CID   257521294.
  12. ↑ Rahman, Imran A.; Darroch, Simon A. F.; Racicot, Rachel A.; Laflamme, Marc (27 November 2015). "Suspension feeding in the enigmatic Ediacaran organism Tribrachidium demonstrates complexity of Neoproterozoic ecosystems". Science Advances. 1 (10): e1500800. Bibcode:2015SciA....1E0800R. doi: 10.1126/sciadv.1500800 . PMC   4681345 . PMID   26702439.
  13. ↑ Glaessner, M. F. (1979). "Precambrian". In Robison, R. A.; Teichen, C. (eds.). Treatise on invertebrate paleontology, Part A. Boulder, Colorado, Geological Society of America: University of Kansas Press. pp. 79–118.
  14. 1 2 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 (in Russian). Moscow: Nauka. pp. 70–106.
  15. ↑ Fedonkin, M. A. (1990). "Precambrian Metazoans". In Briggs D.; Crowther P. (eds.). Palaeobiology: A Synthesis (PDF). Blackwell. pp. 17–24. Archived from the original (PDF) on 12 January 2012. Retrieved 24 March 2013.
  16. ↑ Runnegar, B. N.; Fedonkin, M. A (1992). "Proterozoic Metazoan Body Fossils". In Schopf, J. W.; Klein, C. (eds.). The Proterozoic Biosphere: A Multidisciplinary Study. Cambridge University Press. p. 373. ISBN   9780521366151.
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