Archaeaspinus
Temporal range:
Archaeaspinus fedonkini
Scientific classification
Kingdom:
Animalia
Phylum:
Proarticulata
Class:
Cephalozoa
Family:
Yorgiidae
Genus:
Archaeaspinus

Ivantsov, 2007
Species:
A. fedonkini Ivantsov, 2001
Synonyms
  • Archaeaspis Ivantsov, 2001

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

Background

Archaeaspinus was discovered in Zimnii Bereg, the Winter Coast of the White Sea in Russia, by A. Yu. Ivantsov in 2001.[1] Since then, numerous additional fossils have been attributed to the genus, mostly from that same type locality, but a small number from Flinders Ranges in South Australia as well.[2]

Originally called Archaeaspis—a name already applied to a redlichiid trilobite—in 2001 by Ivantsov, it was later recombined under its current name in 2007 by the same author.[3][1][4] The type species, A. fedonkini is the only species known in this genus. It appears in the fossil record between 571-551Ma.[5]

A. fedonkini, Ivantsov 2007

Description

As with other genera within the family Yorgiidae, Archaeaspinus is discoid. Much of its body segmented by up to 15 bilateral isomers.[2] It has an unsegmented anterior end reminiscent of a head, full of what may be distribution channels. It also contains what appears to be an unpaired lobe which branches off the isomer that is furthest forward to loop within the "head" section, following the shape of the body.[6] This lobe, or perhaps irregular isomer, is bordered by a shallow furrow on the anterior and left edge.[3]

The isomers are arranged in a gliding reflection symmetry, thought to have increased in size and quantity as the organism aged and grew. The dorsal side is covered with evenly spaced tubercles.

Though originally thought to have been soft bodied, it has also been suggested that Archaeaspinus had a delicate, flexible carapace ("cover tissue") covering its dorsal side.[7]

It closely resembles Yorgia, because of the similar anterior region, and to a lesser extent Dickinsonia and other Proarticulates.[8]

Phylogenetic relationships

Archaeaspinus belongs to the phylum Proarticulata. Within that, its class is Cephalozoa and family Yorgiidae.[9][10] Until 2004 Cephalozoans were categorized within the class Vendiamorpha, so older records of the Archaeaspinus may label it a Vendiamorph.[11]

Newer analyses suggest that tissue on the ventral side of most Proarticulates, and therefore Archaeaspinus, bore cilia for feeding.[8]

Paleoecology

Archaeaspinus is thought to have used an osmotrophic or filter-feeding strategy, absorbing nutrients from the microbial mat below in much the same way that Yorgia did.[12]

References

  1. 1 2 Ivantsov, Andrey (January 2004). "New Proarticulata from the Vendian of the Arkhangel'sk Region". {{cite journal}}: Cite journal requires |journal= (help)
  2. 1 2 Mikhail A. Fodonkin, James G. Gehling, Kathleen Grey, Guy M. Narbonne, Patricia Vickers-Rich (2007). The Rise of Animals, Evolution and Diversification of the Kingdom Animalia. Johns Hopkins University Press, Baltimore. p. 261. ISBN 9780801886799.{{cite book}}: CS1 maint: multiple names: authors list (link)
  3. 1 2 Ivantsov, Andrey (January 2001). "Vendia and Other Precambrian "Arthropods"". Paleontological Journal.
  4. ↑ Ivantsov, A. Yu (2007). "Small Vendian transversely Articulated fossils". Paleontological Journal. 41 (2): 113–122. doi:10.1134/S0031030107020013. ISSN 0031-0301. S2CID 86636748.
  5. ↑ Muscente, A. D.; Bykova, Natalia; Boag, Thomas H.; Buatois, Luis A.; Mángano, M. Gabriela; Eleish, Ahmed; Prabhu, Anirudh; Pan, Feifei; Meyer, Michael B.; Schiffbauer, James D.; Fox, Peter (2019-02-22). "Ediacaran biozones identified with network analysis provide evidence for pulsed extinctions of early complex life". Nature Communications. 10 (1): 911. Bibcode:2019NatCo..10..911M. doi:10.1038/s41467-019-08837-3. ISSN 2041-1723. PMC 6384941. PMID 30796215.
  6. ↑ Ivantsov AY (2004). "Vendian Animals in the Phylum Proarticulata" (PDF). The Rise and Fall of the Vendian Biota. IGSP Project 493. Prato, Italy. p. 52
  7. ↑ Fedonkin, Mikhail A. (2003-03-31). "The origin of the Metazoa in the light of the Proterozoic fossil record". Paleontological Research. 7 (1): 9–41. doi:10.2517/prpsj.7.9. ISSN 1342-8144. S2CID 55178329.
  8. 1 2 Ivantsov, A. Yu.; Zakrevskaya, M. A.; Nagovitsyn, A. L. (December 2019). "Morphology of integuments of the Precambrian animals, Proarticulata". Invertebrate Zoology. 16 (1): 19–26. doi:10.15298/invertzool.16.1.03. ISSN 1812-9250.
  9. ↑ "PBDB". paleobiodb.org. Retrieved 2020-11-30.
  10. ↑ "IRMNG - Cephalozoa †". www.irmng.org. Retrieved 2020-11-30.
  11. ↑ Ivantsov, A. Yu.; Fedonkin, M. A.; Nagovitsyn, A. L.; Zakrevskaya, M. A. (September 2019). "Cephalonega, A New Generic Name, and the System of Vendian Proarticulata". Paleontological Journal. 53 (5): 447–454. doi:10.1134/s0031030119050046. ISSN 0031-0301. S2CID 203853224.
  12. ↑ Budd, Graham E.; Jensen, Sören (2017). "The origin of the animals and a 'Savannah' hypothesis for early bilaterian evolution". Biological Reviews. 92 (1): 446–473. doi:10.1111/brv.12239. hdl:10662/8091. ISSN 1469-185X. PMID 26588818. S2CID 39110115.
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