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The Ediacaran Period (named 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 mining from mining activity in the late 19th century....
 of South Australia
South Australia

South Australia is a States and territories of Australia 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....
) is the last geological period of the Neoproterozoic
Neoproterozoic

The Neoproterozoic Era is the unit of geologic time scale from 1,000 to 542 +/- 0.3 million years ago. The terminal Era of the formal Proterozoic Eon , it is further subdivided into the Tonian, Cryogenian, and Ediacaran Periods....
 Era and of the Proterozoic Eon, immediately preceding the Cambrian
Cambrian

The Cambrian is a geologic period that began about Mya at the end of the Proterozoic eon and ended about Ma with the beginning of the Ordovician period ....
 Period, the first period of the Paleozoic
Paleozoic

The Paleozoic or Palaeozoic Era is the earliest of three geology Era of the Phanerozoic Eon . The Paleozoic spanned from roughly , and is subdivided into six period ; from oldest to youngest they are: the Cambrian, Ordovician, Silurian, Devonian period, Carboniferous, and Permian...
 Era and of the Phanerozoic Eon. Its status as an official geological period was ratified in 2004 by the International Union of Geological Sciences
International Union of Geological Sciences

The International Union of Geological Sciences is an international non-governmental organization devoted to international cooperation in the field of geology....
 (IUGS), making it the first new geological period declared in 120 years. The type section
Global Boundary Stratotype Section and Point

A Global Boundary Stratotype Section and Point, abbreviated GSSP, is an internationally agreed upon stratigraphy section which serves as the reference section for a particular boundary on the geologic time scale....
 is in the Flinders Ranges
Flinders Ranges

Flinders Ranges is the largest mountain range in South Australia, which starts approximately 200 km north west of Adelaide, Australia. The discontinuous ranges stretch for over 430 km from Port Pirie to Lake Callabonna....
 in South Australia.






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The Ediacaran Period (named 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 mining from mining activity in the late 19th century....
 of South Australia
South Australia

South Australia is a States and territories of Australia 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....
) is the last geological period of the Neoproterozoic
Neoproterozoic

The Neoproterozoic Era is the unit of geologic time scale from 1,000 to 542 +/- 0.3 million years ago. The terminal Era of the formal Proterozoic Eon , it is further subdivided into the Tonian, Cryogenian, and Ediacaran Periods....
 Era and of the Proterozoic Eon, immediately preceding the Cambrian
Cambrian

The Cambrian is a geologic period that began about Mya at the end of the Proterozoic eon and ended about Ma with the beginning of the Ordovician period ....
 Period, the first period of the Paleozoic
Paleozoic

The Paleozoic or Palaeozoic Era is the earliest of three geology Era of the Phanerozoic Eon . The Paleozoic spanned from roughly , and is subdivided into six period ; from oldest to youngest they are: the Cambrian, Ordovician, Silurian, Devonian period, Carboniferous, and Permian...
 Era and of the Phanerozoic Eon. Its status as an official geological period was ratified in 2004 by the International Union of Geological Sciences
International Union of Geological Sciences

The International Union of Geological Sciences is an international non-governmental organization devoted to international cooperation in the field of geology....
 (IUGS), making it the first new geological period declared in 120 years. The type section
Global Boundary Stratotype Section and Point

A Global Boundary Stratotype Section and Point, abbreviated GSSP, is an internationally agreed upon stratigraphy section which serves as the reference section for a particular boundary on the geologic time scale....
 is in the Flinders Ranges
Flinders Ranges

Flinders Ranges is the largest mountain range in South Australia, which starts approximately 200 km north west of Adelaide, Australia. The discontinuous ranges stretch for over 430 km from Port Pirie to Lake Callabonna....
 in South Australia. It overlaps, but is shorter than the Vendian period, a name that was earlier proposed by Boris Sokolov
Boris Sokolov

Boris Sokolov is a historian and a Russian literature researcher . In 1979 he graduated from the department of geography of the Moscow State University, specialising in economic geography....
 of Russia
Russia

Russia , or the Russian Federation , is a list of countries spanning more than one continent country extending over much of northern Eurasia....
. In 1952, Boris Sokolov proposed the name Vendian to label a discrete system of siliciclastic
Siliciclastic

Siliciclastic rocks are clastic noncarbonate sedimentary rocks that are almost exclusively silica-bearing, either as forms of quartz or other silicate minerals....
 rocks.

Base of the Ediacaran

Although the Ediacaran Period does contain soft-bodied fossil
Fossil

Fossils are the preserved remains or trace fossil of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous Rock formations and sedimentary rock layers is known as the fossil record....
s, it is unusual in comparison to later periods because its beginning is not defined by a change in the fossil record. Rather, the beginning is defined at the base of a chemically distinctive carbonate
Carbonate

In chemistry, a carbonate is a salt or ester of carbonic acid....
 layer, referred to as a "cap carbonate
Cap carbonate

Cap carbonates are layers of distinctively textured carbonate rock s which typically form the uppermost layer of sedimentary sequences reflecting major glaciations in the geological record....
", because it caps glacial
Glacier

A glacier is a large, slow-moving mass of ice, formed from compacted layers of snow, that slowly deforms and flows in response to gravity and high pressure....
 deposits and indicates a sudden climatic change at the end of an ice age
Ice age

The general term "ice age" or, more precisely, "glacial age" denotes a geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in an expansion of continental ice sheets, polar ice sheets and alpine glaciers....
. This bed is characterized by an unusual depletion of 13C
Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
, but most large isotopic excursions in the Ediacaran period are too large to represent a global signal, and must reflect local changes.

Dating

No dating
Absolute dating

Absolute dating is the process of determining a specific date for an archaeology or Palaeontology site or artifact. Some archaeologists prefer the terms chronometric or calendar dating, as use of the word "absolute" implies a certainty and precision that is rarely possible in archaeology....
 has been possible at the type section of the Ediacaran Period in South Australia. Therefore the age range of 635 to 542 million years before the present is based on correlations to other countries where dating has been possible. The base age of approximately 635 million years ago is based on U-Pb (uranium
Uranium

Uranium is a silvery-gray metallic chemical element in the actinide series of the periodic table that has the chemical symbol U and atomic number 92....
-lead
Lead

Lead is a main-group Chemical element with symbol Pb and atomic number 82. Lead is a soft, malleable poor metal, also considered to be one of the heavy metal ....
) isochron dating
Isochron dating

Isochron dating is a common technique of radiometric dating and is applied to date certain events, such as crystallization, metamorphism, shock events, and differentiation of precursor melts, in the history of rock ....
 from Namibia
Namibia

Namibia, officially the Republic of Namibia, is a country in southern Africa on the Atlantic Ocean coast. It shares borders with Angola and Zambia to the north, Botswana to the east, and South Africa to the south....
 and China. Applying this age to the base of the Ediacaran assumes that individual cap carbonates are synchronous around the world and that the correct cap carbonate layers have been correlated between Australian and Namibia. This is controversial because an age of about 580 million years has been obtained in association with glacial rocks in Tasmania
Tasmania

Tasmania is an Australian island and States and territories of Australia of the same name. It is located south of the eastern side of the continent, being separated from it by Bass Strait....
 which some scientists tentatively correlate with those just beneath the Ediacaran rocks of the Flinders Ranges. The age of the top is the same as the widely recognised age for the base of the Cambrian
Cambrian

The Cambrian is a geologic period that began about Mya at the end of the Proterozoic eon and ended about Ma with the beginning of the Ordovician period ....
 Period 542± 0.3 Ma (million years ago).

Biota


The animal fossil record from this period is sparse, possibly because animals had yet to evolve hard shells, which make for easier fossilization. The Ediacaran biota include the oldest definite multicellular organism
Multicellular organism

Multicellular organisms are organisms consisting of more than one cell , and having differentiated cells that perform specialized functions in the cell....
s with tissues, and the most common types resemble segmented worms, fronds, disks, or immobile bags. They bear little resemblance to modern lifeforms, and their relationship even with the later lifeforms of the Cambrian explosion
Cambrian explosion

The Cambrian explosion or Cambrian radiation was the seemingly rapid appearance of most major groups of complex animals around , as evidenced by the fossil record....
 is difficult to interpret. More than 100 genera
Genus

A genus is a low-level taxonomic rank used in the classification of living and fossil organisms. The taxonomic ranks are domain , kingdom , phylum, class , order , family , genus, and species....
 have been described, and well known forms include Arkarua
Arkarua

Arkarua is a small, Precambrian disk-like fossil with a raised center, a number of radial ridges on the rim, and a five-pointed central depression marked with radial lines of 5 small dots from the middle of the disk center....
, Charnia
Charnia

Charnia is the genus name given to a frond-like Ediacaran lifeform with segmented ridges branching alternately to the right and left from a zig-zag medial suture....
, Dickinsonia
Dickinsonia

Dickinsonia is an iconic fossil of the Ediacaran biota. It resembles a bilaterally symmetrical ribbed oval. Its affinities are presently unknown; most interpretations consider it to be an animal, although others suggest it may be fungal, or a member of an "extinct kingdom"....
, Ediacaria
Ediacaria

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 of the Upper Riphean to 501 million years ago, well into the Cambrian Peri...
, Marywadea
Marywadea

Marywadea is a genus of Ediacaran biota shaped like an oval with a central ridge. It is a bilaterian organism as evidenced by its symmetry ....
, Onega
Onega (fossil)

Onega stepanovi is one of the lesser known Ediacara biota from the Ediacaran Period, it was described by Mikhail A. Fedonkin in 1976and was placed in the Phylum Proarticulata in 1985....
, Pteridinium
Pteridinium

Pteridinium is a fossil found in a number of Precambrian deposits worldwide. It is a member of the Ediacaran biota.The fossil is common in late Precambrian deposits in South Australia, Namibia, and the White Sea region of Russia....
, and Yorgia
Yorgia

Yorgia waggoneri Ivantsov, 1999is a member of the Ediacara biota, and resembles a cross between the organisms Dickinsonia and Spriggina....
.

In addition, there are unverified claims of "footprints" - tracks made by legged organisms thought to resemble arthropods or legged worms. The significance of these finds awaits their publication.

See also

  • List of fossil sites
    List of fossil sites

    This is a worldwide list of important and/or well-known localities where fossils have been found. Such locations may either be a geological formation or a single site....
     (with link directory)


External links


  • – Catalyst (Australian Broadcasting Corporation
    Australian Broadcasting Corporation

    The Australian Broadcasting Corporation, commonly referred to as the ABC, is Australia's national Public broadcasting.With a budget of Australian dollar840 million annually, the corporation provides television, radio, online and mobile services throughout metropolitan and regional Australia, as well as overseas through the Australia Net...
    )