View source for Ausia fenestrata

{{Short description|Genus of marine filter feeders}}
{{Speciesbox
|fossil_range = [[Ediacaran]] {{fossil range|635|539}}
| image = Ausia.jpg
| image2 = Ausia2.jpg
| image2_caption = Fossil and M. Fedonkin reconstruction of ''Ausia'' as sponge-like organism
| taxon = Ausia fenestrata
| parent_authority = Hahn and Pflug, 1985
| authority = Hahn and Pflug, 1985<ref name= Hahn_Pflug_1985>{{cite journal 
 |author1=Hahn, G. |author2=Pflug, H. D. | year = 1985
 | title = Polypenartige Organismen aus dem Jung-Präkambrium (Nama-Gruppe) von Namibia
 | journal = Geologica et Palaeontologica
 | volume = 19
 | pages = 1–13
}}</ref>
}}

'''''Ausia fenestrata''''' is an  [[Ediacaran|Ediacaran period]] (635 – 539 million years ago)<ref>{{cite web |title=Stratigraphic Chart 2022 |url=https://stratigraphy.org/ICSchart/ChronostratChart2022-02.pdf |publisher=International Stratigraphic Commission | date=February 2022  |access-date=25 April 2022}}</ref> [[fossil]] represented by only one specimen 5&nbsp;cm long from the [[Nama Group]], a [[Vendian]] to [[Cambrian]] group of stratigraphic sequences deposited in the Nama foreland basin in central and southern [[Namibia]].<ref name= Hahn_Pflug_1985/> It has similarity to ''[[Burykhia]]'' from Ediacaran (Vendian) [[siliciclastic]] sediments exposed on the Syuzma River of [[Arkhangelsk Oblast]], northwest Russia.<ref name=IGCP>{{Cite web |url=http://www.geosci.monash.edu.au/precsite/docs/reports/canadian-ar03.pdf |title=IGCP 493 Annual Report 2003 |access-date=2008-11-20 |archive-url=https://web.archive.org/web/20080721220025/http://www.geosci.monash.edu.au/precsite/docs/reports/canadian-ar03.pdf |archive-date=2008-07-21 |url-status=dead }}</ref><ref name=Fedonkin_1996/><ref name=Oslo_2008/>
This fossil is of the form of an elongate bag-like sandstone cast (Nama-type preservation) tapering to a cone on one end. The surface of the fossil is covered with oval depressions ("windows") regularly spaced over the surface in the manner of concentric/parallel rows. The taxonomic identity of ''Ausia'' is unresolved.

==Interpretations==
* G. Hahn and H. D. Pflug suggested that ''Ausia'' is a [[pennatulacea]]n coral from the family Veretillidae, but there are no signs of secondary polyps on the fossil, which are nonetheless represented in Hahn and Pflug's reconstruction.<ref name=Hahn_Pflug_1985/> No veretillids are represented in the fossil record as far as is known.<ref name=Williams>{{cite journal
 | author = Gary C. Williams
 | title = Aspects of the Evolutionary Biology of Pennatulacean Octocorals
 | url = http://research.calacademy.org/research/izg/EvolutionaryBiology.htm
}}</ref>
* Some researchers have assumed that these depressions are pores and interpreted  ''Ausia'' as an ancestor of [[Archaeocyatha|archeocyathans]] and other sponge-like organisms<ref name=Fedonkin_1996>M. A. Fedonkin (1996). "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, p. 90-91.</ref> or true [[sponge]].<ref name= McMenamin>Mark A. S. McMenamin (1998). "The Sand Menagerie". In: ''The Garden of Ediacara: Discovering the First Complex Life''. Columbia University Press. New York. pp.11-46.</ref> But [[Adolf Seilacher]] has argued that the "windows" are merely dimples.<ref name= McMenamin/>
* ''Ausia'' may represent [[ascidians]] (sea squirts),<ref name="Fedonkin2012">{{Cite journal | last1 = Fedonkin | first1 = M. A. | last2 = Vickers-Rich | first2 = P. | last3 = Swalla | first3 = B. J. | last4 = Trusler | first4 = P. | last5 = Hall | first5 = M. | title = A new metazoan from the Vendian of the White Sea, Russia, with possible affinities to the ascidians | journal = Paleontological Journal | volume = 46 | pages = 1–11 | year = 2012 | issue = 1 | doi = 10.1134/S0031030112010042 | bibcode = 2012PalJ...46....1F | s2cid = 128415270 }}</ref> an invertebrate group related to the [[chordates]].<ref name=Oslo_2008/><ref name=Vickers-Rich>Vickers-Rich P. (2007). "Chapter 4. The Nama Fauna of Southern Africa". In: Fedonkin M.A., Gehling J.G., Grey K., Narbonne G.M., Vickers-Rich P. ''The Rise of Animals: Evolution and Diversification of the Kingdom Animalia'', Johns Hopkins University Press. pp. 69-87</ref> Results of a new study of a ''[[Burykhia]]'' from Russia have shown a possible affinity of these organisms to the ascidians, which are [[urochordates]]. The Russian species is more than 90&nbsp;mm across, and the rows of oval depressions are separated by structures which were probably grooves in the internal wall surface of the living organism. The study's authors interpret these fossils as the internal sand casts of a vast bag-like cavity, possibly a pharynx or branchial basket.<ref name=Oslo_2008>M.A. Fedonkin, P. Vickers Rich, B. Swalla, P. Trusler, M. Hall. (2008). "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". HPF-07 Rise and fall of the Ediacaran (Vendian) biota. International Geological Congress - Oslo 2008.</ref> The animals represented by these two genera were thought to live in the shallow waters of an epicontinental sea, slightly more than 555-548 million years ago, and the authors feel this is probably the oldest evidence of the chordate lineage of metazoans.<ref name=Oslo_2008/>
* Jerzy Dzik has suggested that ''Ausia'' bears some similarity to the [[halkieriid]]s, and resembles the body plan that might be expected of halkieriid ancestors under the [[coeloscleritophoran]] hypothesis.<ref name=Dzik2009>{{walcott 2009|dzik}}</ref><ref>{{Cite journal|journal=Palaeontographica Canadiana|title=Possible Ediacaran ancestry of the halkieriids|author=Dzik, J.|year=2011|volume=21|pages=205–218}}</ref>

<gallery>
Ausia3.jpg|Hahn and Pflug reconstruction of ''Ausia'' as a [[pennatulacea]]n
Ausia fenestra.jpg|Reconstructed as a tunicate
</gallery>

==See also==
*[[List of Ediacaran genera]]
*''[[Yarnemia]]'', another Ediacaran thought to be a tunicate.

==References==
{{Reflist}}
{{Tunicata|F.}}
{{Taxonbar|from1=Q4822760|from2=Q130356471}}

[[Category:Ediacaran life]]
[[Category:Fossils of Namibia]]
[[Category:Fossil taxa described in 1985]]