Nevertheless, the definitions of the lower and upper boundaries of the Ediacaran on the basis of chemostratigraphy and ichnofossils are disputable.

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.

The earliest fossils of multicellular life are found in the Ediacaran, including the earliest animals.

These were most commonly known as Vendian biota until the formal naming of the Period, and are currently known as Ediacaran biota.

Others acknowledge a few possible or even likely relationships but feel that most of the Ediacaran forms are representatives of unknown animal types.

These are referred to as Ediacaran or Vendian biota.

** Animals that live interstitially in the sand of the ocean floor were responsible for the fossil crawling traces that are considered the earliest evidence of animals and are detectable even prior to the dawn of the Ediacaran Period in geology.

** Animals that incorporated algae as photosynthetically active endosymbionts, i. e. primarily obtaining their nutrients from their partners in symbiosis, were accordingly responsible for the mysterious creatures of the Ediacara fauna that are not assigned to any modern animal taxon and lived during the Ediacaran Period, before the start of the Paleozoic.

They are among the earliest and most abundant of the small shelly fossils with mineralized skeletons, and therefore feature in the debate about why such skeletons first appeared in the Late Ediacaran.

The extreme cooling of the global climate around 700 million years ago ( the so called Snowball Earth of the Cryogenian period ) and the rapid evolution of primitive life during the subsequent Ediacaran and Cambrian periods are often thought to have been triggered by the breaking up of Rodinia.

There are no identified related forms, although there is some vague resemblance to other Ediacaran forms such as Dickinsonia and Spriggina that share some of its enigmatic characteristics, such as the " staggered " or " glide symmetry " of its units.

Claims that earlier Ediacaran fossils are brown algae have since been dismissed.

The organisms are preserved in positive or negative relief, usually in coarse sandstone, and are usually preserved by virtue of imprinting on microbial mats, though their preservation may also reflect the abundance of aerobic environments or microbial pyritisation in the Ediacaran era — or, if they are protists, possibly agglutination ( although this hypothesis is not mainstream ).

Contrary to widely circulated opinion that Ediacaran burrows are only horizontal the vertical burrows Skolithos are also known.

The formation is of particular interest because it appears to cover the boundary between the problematic organisms of the Ediacaran geological period and the more familiar fauna of the Cambrian explosion of lifeforms whose descendents are recognizable.

There are also two enigmatic species from the Ediacaran period-Ausia fenestrata from the Nama Group of Namibia and a second new Ausia-like genus from the Onega Peninsula, White Sea of northern Russia.

The White Sea fossils are often associated with the Ediacaran " animals " Tribrachidium and Dickinsonia ; meandering trace fossil trails, possibly made by Kimberella ; and algae.

The Avalon Peninsula is a noted region for Precambrian fossils, and many Lagerstätten of the diverse Ediacaran biota are found on the peninsula.

The sea pen fossil record is patchy and disputed by some ; while the earliest accepted fossils are known from the Cambrian-aged Burgess Shale ( Thaumaptilon ), similar fossils from the Ediacaran ( ala Charnia ) may represent the dawn of sea pens.

Definitive, macroscopic remains of these metazoans are found in the fossil record from the Ediacaran period of the Neoproterozoic era onwards, although they do not become common until the Late Devonian period in the latter half of the Paleozoic era.

Arkarua is known only from the Ediacaran beds of the Flinders Ranges in South Australia, and takes its name from a mythical giant snake of the local Aboriginal people ( Gehling 1987 ).

Ausia fenestrata is a curious Ediacaran period ( 630 – 542 million years ago ) fossil represented by only one specimen 5 cm long from the Nama Group of Namibia and it has similarity to Burykhia from Ediacaran ( Vendian ) siliciclastic sediments exposed on the Syuzma River of northern Russia.

Kimberella is a monospecific genus of bilaterian known only from rocks of the Ediacaran period.

The terminal Era of the formal Proterozoic Eon ( or the informal " Precambrian "), it is further subdivided into the Tonian, Cryogenian, and Ediacaran Periods.

There is no convincing fossil record of the placozoa, although the Ediacaran biota ( Precambrian, ) organism Dickinsonia appears to be closely allied with this phylum.

However, some Precambrian ( Ediacaran ) organisms produced tough outer shells, while others, such as Cloudina, had a calcified exoskeleton.

Some Precambrian ( Ediacaran ) organisms produced tough but non-mineralized outer shells, while others, such as Cloudina, had a calcified exoskeleton, but mineralized skeletons did not become common until the beginning of the Cambrian period, with the rise of the " small shelly fauna ".

Although the Ediacaran Period does contain soft-bodied fossils, it is unusual in comparison to later periods because its beginning is not defined by a change in the fossil record.

The Cambrian period follows the Ediacaran and is followed by the Ordovician period.

The Ediacaran Period overlaps, but is shorter than the Vendian Period, a name that was earlier, in 1952, proposed by Russian geologist and paleontologist Boris Sokolov.

The GSSP of the upper boundary of the Ediacaran is the lower boundary of the Cambrian on the SE coast of Newfoundland approved by the International Commission on Stratigraphy as a preferred alternative to the base of the Tommotian Stage in Siberia which was selected on the basis of the ichnofossils Treptichnus pedum.

The well-identified events of this eon were the transition to an oxygenated atmosphere during the Mesoproterozoic ; several glaciations, including the hypothesized Snowball Earth during the Cryogenian period in the late Neoproterozoic ; and the Ediacaran Period ( 635 to 542 Ma ) which is characterized by the evolution of abundant soft-bodied multicellular organisms.

The first bona fide radula dates to the Early Cambrian, although trace fossils from the earlier Ediacaran have been suggested to have been made by the radula of the organism Kimberella.

Dickinsonia was first described by Reg Sprigg, the original discoverer of the Ediacaran biota in Australia, who named it after Ben Dickinson, then Director of Mines for South Australia, and head of the government department that employed Sprigg.

Taken as a whole, the Doushantuo Formation ranges from about 635 Ma ( million years ) ago at its base to about 551 Ma at its top, predating by perhaps five Ma the earliest of the ' classical ' Ediacaran faunas from Mistaken Point on the Avalon peninsula of Newfoundland, and recording conditions a good forty to fifty million years before the Cambrian explosion.

It forms the second geologic period of the Neoproterozoic Era, preceded by the Tonian Period and followed by the Ediacaran.

They cite the Cambrian explosion — the appearance of abundant fossils in the upper Ediacaran ( Vendian ) Period and lower Cambrian Period — as the pre-Flood / Flood boundary, the presence in such sediments of fossils that do not occur later in the geological record as part of a pre – flood biota that perished and the absence of fossilized organisms that appear later, such as angiosperms and mammals, as due to erosion of sediments deposited by the flood as waters receded off the land.

The Rangeomorphs are a form taxon of frondose Ediacaran fossils that are united by a similarity to Rangea.

The mountains are formed of metamorphic rocks made from sediments deposited during the Ediacaran Period ( as indicated by the presence of characteristic fossils ).

The ' golden spike ' ( bronze disk in the lower section of the image ) or ' type section ' of the Global Boundary Stratotype Section and Point ( GSSP ) for the base of Ediacaran period.

Elatina Fm diamictite below Ediacaran Global Boundary Stratotype Section and Point | GSSP site in the Flinders Ranges National Park | Flinders Ranges NP, South Australia.

The ' golden spike ' ( bronze disk in the lower section of the image ) or ' type section ' of the Global Boundary Stratotype Section and Point ( GSSP ) for the base of Ediacaran period.