Ausia

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Ausia
Reconstruction of Ausia as a sea feather (Pennatulacea) according to Hahn und Pflug

Reconstruction of Ausia as a sea ​​feather (Pennatulacea) according to Hahn und Pflug

Temporal occurrence
Ediacarium
Locations
Systematics
Multicellular animals (Metazoa)
Tunicates (Tunicata)
Sea squirts (Ascidiae)
Ausia
Scientific name
Ausia
Hahn and Pflug , 1985
species
  • Ausia fenestrata

Ausia is a rather mysterious, extinct animal genus of the Ediacariums , the taxonomic position of which has not been clarified.

Etymology and first description

Ausia is the Latinized feminine of the Aus type locality in Namibia. The taxon name fenestrata (windowed) is derived - in allusion to the many openings in the fossil - from fenestra (or fenestrare ), the Latin word for window.

The fossil was first scientifically described by Hahn and Pflug in 1985 .

Occurrence

The only known fossil of Ausia fenestrata comes from the Kuibis quartzite of the Nama Group , which was deposited at the time of the Ediacarian in the Nama foreland basin in central and southern Namibia .

description

The 75 millimeter long and 15 to 30 millimeter wide fossil is a sandstone impression in typical Nama preservation. It has an elongated, bag-like shape that tapers at one end. The surface is broken up by oval depressions ("windows") that are arranged in parallel, concentric rows at regular intervals.

Taxonomy

The exact taxonomic position of Ausia is not clear. The fossil has similarities to Burykhia from the siliciclastic sediments of the Vendian on the Syusma ( Arkhangelsk Oblast , northern Russia ).

Taxonomic Interpretations

Rooster and plow interpret Ausia as belonging to the Veretillidae family - corals that are part of sea ​​feathers . The fossil shows no signs of secondary polyps , even if the cock and plow show them in their reconstruction drawing. In addition, no veretillids are known in the fossil record .

Some researchers see pores in the depressions and therefore interpret Ausia as an ancestor of archaeocyathids and other sponge-like organisms or real sponges . This view is not shared by Adolf Seilacher , who believes he can only see indentations in the so-called windows.

Perhaps one Ausia to the sea squirts (Ascidiacea), one to master the chordates belong (Chordata) Invertebratengruppe.

Reconstruction of Ausia fenestrata as a tunicate

Russian re-assays where also the family of Ausiidae belonging taxon burykhia create an affinity with the tunicates counting (tunicates) sea squirts (sub-tribe Urochordata) near. This Russian fossil measures over 90 millimeters and its oval depressions, which are arranged in a row, are separated by structures that probably correspond to depressions on the internal wall of the living organism. The authors interpret the Burykhia fossils as an internal sand print of an extensive, bag-like body cavity, possibly a throat or lung sac. Habitat was a shallow epicontinental sea that they populated between 555 and 548 million years old BP . Fedonkin and colleagues see in these fossils the oldest evidence for the branch of the chordates within the multicellular animals (Metazoa).

The related taxon Yarnemia ascidiformis and Inkrylovia are also interpreted as tunicates.

Jerzy Dzik is of the opinion that Ausia bears a certain resemblance to the Halkieriidae , as their physique is exactly the same as the predecessor of the Halkieriidae according to the Coeloscleritopora hypothesis.

Individual evidence

  1. ↑ a b c Hahn, G. and Pflug, HD: Polyp-like organisms from the Young Precambrian (Nama group) of Namibia . In: Geologica et Palaeontologica . tape 19 , 1985, pp. 1-13 .
  2. ↑ a b M. A. Fedonkin: Ausia as an ancestor of archeocyathans, and other sponge-like organisms . In: Enigmatic Organisms in Phylogeny and Evolution. Abstracts . Moscow, Paleontological Institute, Russian Academy of Sciences 1996, p. 90-91 .
  3. ^ A b Mark AS McMenamin: The Sand Menagerie . In: The Garden of Ediacara: Discovering the First Complex Life . Columbia University Press, New York 1998, pp. 11-46 .
  4. ↑ Fedonkin, MA, Vickers-Rich, P., Swalla, BJ, Trusler, P. and Hall, M .: A new metazoan from the Vendian of the White Sea, Russia, with possible affinities to the ascidians . In: Paleontological Journal . tape 46: 1 , 2012, doi : 10.1134 / S0031030112010042 .
  5. ↑ a b M.A. Fedonkin, P. Vickers Rich, B. Swalla, P. Trusler, and M. Hall .: A Neoproterozoic chordate with possible affinity to the ascidians: New fossil evidence from the Vendian of the White Sea, Russia and its evolutionary and ecological implications . In: HPF-07 Rise and fall of the Ediacaran (Vendian) biota . International Geological Congress - Oslo 2008.
  6. ↑ Chistyakov, VG et al .: On the Presence of Vendian Sediments in the Middle Reaches of the Onega River and Possible Existence of Tunicates (Tunicata: Chordata) in the Precambrian . In: Vestn. Leningr. Univ. No. 6 , 1984, pp. 11-19 .
  7. ↑ Fedonkin, MA et al .: The Rise of Animals. Evolution and Diversification of the Kingdom Animalia . Johns Hopkins University Press, Baltilore 2007.
  8. ↑ Dzik, Jerzy: Possible Ediacaran Ancestry of the Halkieriids . Eds .: Smith, Martin R., O'Brien, Lorna J. and Caron, Jean-Bernard. Abstract volume. International Conference on the Cambrian Explosion. Toronto, Ontario, Canada: The Burgess Shale Consortium 2009, ISBN 978-0-9812885-1-2 .
  9. ↑ Dzik, J .: Possible Ediacaran ancestry of the halkieriids . In: Palaeontographica Canadiana . tape 21 , 2011, p. 205-218 .

Web links

Commons : Ausia  - collection of images, videos and audio files