Pseudorhizostomites howchini is an enigmatic member of the Ediacaran Biota which was originally thought to have been a jellyfish of some kind (Sepkoski, 2002).[1] P. howchini is now thought to either have been a pseudofossil, a gas escape structure or perhaps the result of a rangeomorph holdfast being pulled by currents or, if any of these possibilities are not true, some other force from the sediments which enclosed the fossil.[2]
| Pseudorhizostomites Temporal range:
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| Pseudorhizostomites howchini fossil | |
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| GN14254 and GN14295 in The History Trust of South Australia collection. | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Genus: | †Pseudorhizostomites Sprigg, 1949 |
| Species: | †P. howchini
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| Binomial name | |
| †Pseudorhizostomites howchini Sprigg, 1949
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| Synonyms | |
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Distribution and discovery
editReginald Sprigg found the Holotype of P. howchini within the Flinders Ranges of South Australia. Fossils of Pseudorhizostomites also occur within the White Sea region of Russia on Zimnii Bereg, the Dniester River Basin of Podolia, Ukraine and Gornaya Baskkiria of the Ryauzyak Basin. These fossils are commonly found at all locations.[2]
Classification and interpretations
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Originally, Sepkoski (2002) suggested the possibility of the problematic fossils as being a Jellyfish.[1] Although a more modern and updated interpretation of P. howchini is it being a pseudo-fossil or a structure caused by the Holdfast of a Petalonamid being pulled out by the currents. Pseudorhizostomites tends to occur around very thin impressions and casts of fossils which are the likely producer of Pseudorhizostomites if they decayed.[3] The decayed parts of the organisms preserved alongside the biogenic structure were also interpreted as escaping through an overlying sand lamina.[4] The species Rugoconites tenuirugosus was thought to be the originator behind P. howchini ; the fossil was also compared with the living Hydrozoan Campanularia.[4]
Description
editPseudorhizostomites howchini is a form which represents a large amount of grooves radiating from a centre, which along the way irregularly branch out from one-another towards the outside. No distinct peripheral boundary is present in fossils. The central part which has the grooves radiating from is often strongly depressed (Negative hyporelief). The diameter of the grooves can often vary significantly, and can be from 9–60 mm in some specimens.[2]
See also
editReferences
edit- ^ a b "mindat.org". Retrieved 19 July 2022.
- ^ a b c Fedonkin, Mikhail A.; Sciences), Mikhail A. (Head Fedonkin, Laboratory of Precambrian Organisms Russian Academy of; Gehling, James G.; Museum), James G. (Senior Curator Gehling, retired 6 27 2019 South Australian; Grey, Kathleen; Narbonne, Guy M.; Vickers-Rich, Patricia; University), Patricia (Director Vickers-Rich, Monash (16 March 2007). The Rise of Animals: Evolution and Diversification of the Kingdom Animalia. JHU Press. ISBN 9780801886799. Retrieved 19 July 2022 – via Google Books.
{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link) - ^ Fedonkin, Mikhail A.; Sciences), Mikhail A. (Head Fedonkin, Laboratory of Precambrian Organisms Russian Academy of; Gehling, James G.; Museum), James G. (Senior Curator Gehling, retired 6 27 2019 South Australian; Grey, Kathleen; Narbonne, Guy M.; Vickers-Rich, Patricia; University), Patricia (Director Vickers-Rich, Monash (17 August 1990). The Vendian System: Paleontology. Springer. ISBN 9780801886799. Retrieved 19 July 2022 – via Google Books.
{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link) - ^ a b The Dawn of Animal Life: A Biohistorical Study. CUP Archive. 20 June 1985. ISBN 9780521312165.