Cyclomedusa is a circular fossil of the Ediacaran biota; it has a circular bump in the middle and as many as five circular growth ridges around it. Many specimens are small, but specimens in excess of 20 cm are known. The concentric disks are not necessarily circular, especially when adjacent individuals interfere with each other's growth. Many radial segment lines — somewhat pineapple-like — extend across the outer disks. A few specimens show what might be a stem extending from the center in some direction or other.
Cyclomedusa is widely distributed in Ediacaran strata, with a number of species described. It has also been found in sediments dating to the Mayanian (~1,000 million years ago).[1]Cyclomedusa was originally thought to be a jellyfish[2] but some specimens seem to be distorted to accommodate adjacent specimens on the substrate, apparently indicating a benthic (bottom-dwelling) creature.[3] The markings do not match the musculature pattern of modern jellyfish. The fossils have been conjectured to represent a holdfast for some stalked form — possibly an octacorallian, or something else entirely.[4] Alternatively, it was thought[citation needed] that the described species actually represent different modes of preservation for one organism or that several different organisms have been grouped together under one name as a form taxon.
It is now suggested that Cyclomedusa was a microbial colony;[5] D. Grazhdankin reinterprets the concentric rings and radial structures as comparable to those seen in modern-day microbial colonies exposed to homogeneously distributed environmental conditions.
^Khomentovsky, V.; Nagovitsin, K.; Postnikov, A. (2008). "Mayanian (1100–850 Ma) – Prebaikalian Upper Riphean of Siberia". Russian Geology and Geophysics. 49 (1): 1–6. Bibcode:2008RuGG...49....1K. doi:10.1016/j.rgg.2007.12.001.
^* Sprigg, R. C. (1947): "Early Cambrian jellyfishes (?) from the Flinders Range, South Australia", Transactions of the Royal Society of South Australia. 71.2, p. 220
^(University of California at Berkeley) Cyclomedusa
^(Queens University) "Disk-Form Fossils of Canada" 2012-02-05 at the Wayback Machine. Adolf Seilacher, in a series of papers (1985-92) called into question the assignment of the Ediacaran organisms to Animalia.
^GRAZHDANKIN, D.; GERDES, G. (2007). "Ediacaran microbial colonies". Lethaia. 40 (3): 201–210. doi:10.1111/j.1502-3931.2007.00025.x. Archived from the original on 2013-01-05.
^The few Ediacaran biota that survived into the Cambrian are discussed by Conway Morris 1993 and Narbonne 1998. However, if Cyclomedusa was a microbial colony, related microbes may be extant.
External links
(University of California at Berkeley) Cyclomedusa
April 13, 2023
cyclomedusa, circular, fossil, ediacaran, biota, circular, bump, middle, many, five, circular, growth, ridges, around, many, specimens, small, specimens, excess, known, concentric, disks, necessarily, circular, especially, when, adjacent, individuals, interfer. Cyclomedusa is a circular fossil of the Ediacaran biota it has a circular bump in the middle and as many as five circular growth ridges around it Many specimens are small but specimens in excess of 20 cm are known The concentric disks are not necessarily circular especially when adjacent individuals interfere with each other s growth Many radial segment lines somewhat pineapple like extend across the outer disks A few specimens show what might be a stem extending from the center in some direction or other CyclomedusaTemporal range Mayanian Ediacaran Pha Proterozoic Archean Had nTwo large and small specimens of cyclomedusaScientific classificationKingdom Animalia Genus CyclomedusaSprigg 1947Species C davidiiBinomial name Cyclomedusa davidiiSprigg 1947Cyclomedusa is widely distributed in Ediacaran strata with a number of species described It has also been found in sediments dating to the Mayanian 1 000 million years ago 1 Cyclomedusa was originally thought to be a jellyfish 2 but some specimens seem to be distorted to accommodate adjacent specimens on the substrate apparently indicating a benthic bottom dwelling creature 3 The markings do not match the musculature pattern of modern jellyfish The fossils have been conjectured to represent a holdfast for some stalked form possibly an octacorallian or something else entirely 4 Alternatively it was thought citation needed that the described species actually represent different modes of preservation for one organism or that several different organisms have been grouped together under one name as a form taxon It is now suggested that Cyclomedusa was a microbial colony 5 D Grazhdankin reinterprets the concentric rings and radial structures as comparable to those seen in modern day microbial colonies exposed to homogeneously distributed environmental conditions Cyclomedusa is known from Neoproterozoic beds in Ediacara Australia Finnmark Norway Charnwood Forest England Olenek Russia North China Newfoundland Northwest Canada Podolia Ukraine the Ural Mountains Russia the White Sea Russia and Sonora Mexico It is regarded as a member of the Ediacaran biota a group of somewhat obscure organisms that thrived just before most of the modern multicellular animal phyla appeared Cyclomedusa has no known relatives 6 See also EditList of Ediacaran generaReferences Edit Khomentovsky V Nagovitsin K Postnikov A 2008 Mayanian 1100 850 Ma Prebaikalian Upper Riphean of Siberia Russian Geology and Geophysics 49 1 1 6 Bibcode 2008RuGG 49 1K doi 10 1016 j rgg 2007 12 001 Sprigg R C 1947 Early Cambrian jellyfishes from the Flinders Range South Australia Transactions of the Royal Society of South Australia 71 2 p 220 University of California at Berkeley Cyclomedusa Queens University Disk Form Fossils of Canada Archived 2012 02 05 at the Wayback Machine Adolf Seilacher in a series of papers 1985 92 called into question the assignment of the Ediacaran organisms to Animalia GRAZHDANKIN D GERDES G 2007 Ediacaran microbial colonies Lethaia 40 3 201 210 doi 10 1111 j 1502 3931 2007 00025 x Archived from the original on 2013 01 05 The few Ediacaran biota that survived into the Cambrian are discussed by Conway Morris 1993 and Narbonne 1998 However if Cyclomedusa was a microbial colony related microbes may be extant External links Edit University of California at Berkeley Cyclomedusa Retrieved from https en wikipedia org w index php title Cyclomedusa amp oldid 1123224131, wikipedia, wiki, book, books, library,
