Ediacaria
Encyclopedia
Ediacaria is a fossil
genus
dating to the Ediacaran
Period of the Neoproterozoic
Era. Unlike most Ediacaran biota which disappeared almost entirely from the fossil record at the end of the Period, Ediacaria fossils have been found dating from the Baikalian age (850–650 Ma) of the Upper Riphean to 501 million years ago, well into the Cambrian
Period. Ediacaria consists of concentric rough circles, radial lines between the circles and a central dome, with a diameter from 1 to 70 cm.
in 1947, after the Ediacara Hills
(from Aborigine
Idiyakra "water is present" or a mispronunciation of Yata Takarra, "hard/stony ground"http://aussieheritage.com.au/listings/sa/Parachilna/EdiacaraFossilSite-Nilpena/9895) in South Australia
. Two species are recognised: E. flindersi, described by Sprigg from the Pound Quartzite
in the Ediacara Hills, and E. booleyi, described in 1995 from a Late Cambrian deposit at Booley Bay (County Wexford
), Ireland
. The species were named after the Flinders Ranges
and Booley Bay, respectively.
Ediacaria is possibly a synonym for Aspidella
terranovica described in 1872. Although Ediacaria is one of the first described organisms from the Precambrian, Aspidella was described earlier, although its age was not understood to be Precambrian. As Aspidella is apparently a form taxon
, Ediacaria may yet be valid and denote one specific genus among several that seem to make up Aspidella. Spriggina
wadea is quite likely a synonym of Ediacaria (and consequently, possibly Aspidella); the differences seem to be merely due to different substrate in which the animals were embedded. (Gehling et al. 2000)
Ediacaria was often classified as a jellyfish (a Scyphozoa
n Cnidaria
n), and has also been interpreted in many of the categories postulated to house the Ediacaran biota. A conspicuous filamentous microstructure preserved in some pyritised
specimens appears to conclusively prove that it was in fact a microbial colony, which disrupted the surrounding microbial mat to create the distinctive pattern (Grazhdankin, in press).
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
dating to the Ediacaran
Ediacaran
The Ediacaran Period , named after the Ediacara Hills of South Australia, is the last geological period of the Neoproterozoic Era and of the Proterozoic Eon, immediately preceding the Cambrian Period, the first period of the Paleozoic Era and of the Phanerozoic Eon...
Period of the Neoproterozoic
Neoproterozoic
The Neoproterozoic Era is the unit of geologic time from 1,000 to 542.0 ± 1.0 million years ago. The terminal Era of the formal Proterozoic Eon , it is further subdivided into the Tonian, Cryogenian, and Ediacaran Periods...
Era. Unlike most Ediacaran biota which disappeared almost entirely from the fossil record at the end of the Period, Ediacaria fossils have been found dating from the Baikalian age (850–650 Ma) of the Upper Riphean to 501 million years ago, well into the Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
Period. Ediacaria consists of concentric rough circles, radial lines between the circles and a central dome, with a diameter from 1 to 70 cm.
Systematics and taxonomy
Ediacaria was named by Reg SpriggReg Sprigg
Reginald Claude Sprigg, AO, HonDSc ANU, HonDSc Flinders, MSc Adelaide, FTSE was an Australian geologist and conservationist. At age 17 he became the youngest Fellow of the Royal Society of South Australia. In 1946, in the Ediacara Hills, South Australia he discovered the Ediacara biota, an...
in 1947, after the Ediacara Hills
Ediacara Hills
Ediacara Hills are a range of low hills in the northern part of the Flinders Ranges of South Australia, around 650 km north of Adelaide. The area has many old copper and silver mines from mining activity in the late 19th century...
(from Aborigine
Indigenous Australians
Indigenous Australians are the original inhabitants of the Australian continent and nearby islands. The Aboriginal Indigenous Australians migrated from the Indian continent around 75,000 to 100,000 years ago....
Idiyakra "water is present" or a mispronunciation of Yata Takarra, "hard/stony ground"http://aussieheritage.com.au/listings/sa/Parachilna/EdiacaraFossilSite-Nilpena/9895) in South Australia
South Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
. Two species are recognised: E. flindersi, described by Sprigg from the Pound Quartzite
Quartzite
Quartzite is a hard metamorphic rock which was originally sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to gray, though quartzites often occur in various shades of pink...
in the Ediacara Hills, and E. booleyi, described in 1995 from a Late Cambrian deposit at Booley Bay (County Wexford
County Wexford
County Wexford is a county in Ireland. It is part of the South-East Region and is also located in the province of Leinster. It is named after the town of Wexford. In pre-Norman times it was part of the Kingdom of Uí Cheinnselaig, whose capital was at Ferns. Wexford County Council is the local...
), Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
. The species were named after the Flinders Ranges
Flinders Ranges
Flinders Ranges is the largest mountain range in South Australia, which starts approximately north west of Adelaide. The discontinuous ranges stretch for over from Port Pirie to Lake Callabonna...
and Booley Bay, respectively.
Ediacaria is possibly a synonym for Aspidella
Aspidella
Aspidella is an Ediacaran disk-shaped fossil.- Morphology :Aspidella consists of disk-shaped fossils, with concentric rings and/or centripetal rays. The diameter of circular Aspidella varies from 1 to 180 mm. Most individuals are between 4 and 10 mm, however; smaller animals would...
terranovica described in 1872. Although Ediacaria is one of the first described organisms from the Precambrian, Aspidella was described earlier, although its age was not understood to be Precambrian. As Aspidella is apparently a form taxon
Form taxon
Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships...
, Ediacaria may yet be valid and denote one specific genus among several that seem to make up Aspidella. Spriggina
Spriggina
Fossils of Spriggina are known from the Ediacaran period, around . The segmented organism reached about 3 cm in length and may have been predatory...
wadea is quite likely a synonym of Ediacaria (and consequently, possibly Aspidella); the differences seem to be merely due to different substrate in which the animals were embedded. (Gehling et al. 2000)
Ediacaria was often classified as a jellyfish (a Scyphozoa
Scyphozoa
Scyphozoa is a class within the phylum Cnidaria, sometimes referred to as the "true jellyfish".The class name Scyphozoa comes from the Greek word skyphos , denoting a kind of drinking cup and alluding to the cup shape of the organism....
n Cnidaria
Cnidaria
Cnidaria is a phylum containing over 9,000 species of animals found exclusively in aquatic and mostly marine environments. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance,...
n), and has also been interpreted in many of the categories postulated to house the Ediacaran biota. A conspicuous filamentous microstructure preserved in some pyritised
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
specimens appears to conclusively prove that it was in fact a microbial colony, which disrupted the surrounding microbial mat to create the distinctive pattern (Grazhdankin, in press).
External links
- Peripatus Home Page: Ediacaran Survivors. Version of 2006-MAY-10. Retrieved 2007-JUN-06.