The Ediacaran is a geological period of the Neoproterozoic Era that spans 96 million years from the end of the Cryogenian Period at 635 Mya to the beginning of the Cambrian Period at 538.8 Mya. It is the last period of the Proterozoic Eon as well as the last of the so-called "Precambrian supereon", before the beginning of the subsequent Cambrian Period marks the start of the Phanerozoic Eon, where recognizable fossil evidence of life becomes common.
The cloudinids, an early metazoan family containing the genera Acuticocloudina, Cloudina and Conotubus, lived in the late Ediacaran period about 550 million years ago. and became extinct at the base of the Cambrian. They formed millimetre-scale conical fossils consisting of calcareous cones nested within one another; the appearance of the organism itself remains unknown. The name Cloudina honors the 20th-century geologist and paleontologist Preston Cloud.
Dickinsonia is a genus of extinct organism, most likely an animal, that lived during the late Ediacaran period in what is now Australia, China, Russia, and Ukraine. It is one of the best known members of the Ediacaran biota. The individual Dickinsonia typically resembles a bilaterally symmetrical ribbed oval. Its affinities are presently unknown; its mode of growth has been considered consistent with a stem-group bilaterian affinity, though various other affinities have been proposed. It lived during the late Ediacaran. The discovery of cholesterol molecules in fossils of Dickinsonia lends support to the idea that Dickinsonia was an animal, though these results have been questioned.
A trace fossil, also known as an ichnofossil, is a fossil record of biological activity by lifeforms but not the preserved remains of the organism itself. Trace fossils contrast with body fossils, which are the fossilized remains of parts of organisms' bodies, usually altered by later chemical activity or by mineralization. The study of such trace fossils is ichnology - the work of ichnologists.
The Doushantuo Formation is a geological formation in western Hubei, eastern Guizhou, southern Shaanxi, central Jiangxi, and other localities in China. It is known for the fossil Lagerstätten in Zigui in Hubei, Xiuning in Anhui, and Weng'an in Guizhou, as one of the oldest beds to contain minutely preserved microfossils, phosphatic fossils that are so characteristic they have given their name to "Doushantuo type preservation". The formation, whose deposits date back to the Early and Middle Ediacaran, is of particular interest because it covers the poorly understood interval of time between the end of the Cryogenian geological period and the more familiar fauna of the Late Ediacaran Avalon explosion, as well as due to its microfossils' potential utility as biostratigraphical markers. Taken as a whole, the Doushantuo Formation ranges from about 635 Ma at its base to about 551 Ma at its top, with the most fossiliferous layer predating by perhaps five Ma the earliest of the 'classical' Ediacaran faunas from Mistaken Point on the Avalon Peninsula of Newfoundland, and recording conditions up to a good forty to fifty million years before the Cambrian explosion at the beginning of the Phanerozoic.
Rangea is a frond-like Ediacaran fossil with six-fold radial symmetry. It is the type genus of the rangeomorphs.
Swartpuntia is a monospecific genus of erniettomorph from the terminal Ediacaran period, with at least three quilted, leaf-shaped petaloids — probably five or six. The petaloids comprise vertical sheets of tubes filled with sand. Swartpuntia specimens range in length from 12 to 19 cm, and in width from 11.5 to 140 cm. The margin is serrated, with a 1 mm wide groove. A 14 mm wide stem extends down the middle, tapering towards the top, and stopping 25 mm from the tip. The stem has a V-shaped ornamentation on it. The original fossils were found at, and named after, the Swartpunt farm between Aus and Rosh Pinah in Namibia. The generic name comes from Swartpunt, meaning black point in reference to the colour of the rocks. The specific name germsi honours Gerard Germs, who studied the Nama formation of geological beds.
The Ediacaranbiota is a taxonomic period classification that consists of all life forms that were present on Earth during the Ediacaran Period. These were enigmatic tubular and frond-shaped, mostly sessile, organisms. Trace fossils of these organisms have been found worldwide, and represent the earliest known complex multicellular organisms. The term "Ediacara biota" has received criticism from some scientists due to its alleged inconsistency, arbitrary exclusion of certain fossils, and inability to be precisely defined.
Bioclasts are skeletal fossil fragments of once living marine or land organisms that are found in sedimentary rocks laid down in a marine environment—especially limestone varieties around the globe, some of which take on distinct textures and coloration from their predominate bioclasts—that geologists, archaeologists and paleontologists use to date a rock strata to a particular geological era.
Embryo fossils are the preserved remains of unhatched or unborn organisms. Many fossils of the 580 million year old Doushantuo Formation have been interpreted as embryos; embryos are also common throughout the Cambrian fossil record.
The Lantian Formation is a 150-meter-thick sequence of rocks deposited in Xiuning County, Anhui Province in southern China during a 90-million-year epoch in the Ediacaran period. Its algal macrofossils are the oldest large and complex fossils known.
The Dengying Formation is an upper Ediacaran fossiliferous geologic formation found in South China. It was deposited on a shallow marine carbonate platform.
Lamonte trevallis is an ichnospecies from the late Ediacaran sediments of the Yangtze Gorges of Southern China. It represented fairly large traces that indicate burrowing behaviour. It had Millimetre-sized traces preserved differently than other Ichnofossils from that time period. Surface-dwelling trackways, vertical burrows and horizontal tunnels are a common characteristic of the trace fossil.
Wutubus annularis is a tubular Ediacaran fossil from China. It is the only species in the genus Wutubus. The genus name was derived from the fossil locality near the village of Wuhe and from Latin tubus (tube), and the species epithet derived from Latin, annularis, with reference to the transverse annulae on the tube.
Pambikalbae is a monospecific genus known from the Ediacaran Period of South Australia. Its morphology resembles the morphology of colonial cnidarians, such as sea pens or siphonophores.
Orbisiana is an Ediacaran benthic organism formed out of series of agglutinated spherical or hemispherical chambers. It is believed to be a close relative of Palaeopascichnus.
Eocyathispongia is a genus of sponge-like organisms which lived in the Ediacaran period about 60 million years before the Cambrian. The current fossil record has found this genus in only one location, the Doushantuo Formation in Guizhou, China. It lived in the shallow parts of seas, filter feeding.
Paracharnia is a reassessed genus of a fossil reported by Ding and Chen (1981). It is the first Ediacaran metazoan fossilized remains found in China, taken from the Shibantan Member, Dengying Formation, Sinian System in the Eastern Yangtze Gorge, Hubei Province. It was initially classified as Charnia dengyingensis, but Sun Weiguo in 1986, comparing this to findings from Charnwood in England and the Ediacara assemblage of South Australia, identified it as a new genera. Paracharnia is a pennatulid within the taxon of Rangeomorpha. It is closely associated with macroscopic algal remains of Vendotaenia and dense Cambrian shelly fossil deposits, suggesting its paleontological relevance.
Shuhai Xiao is a paleontologist and professor of geobiology at Virginia Tech, Blacksburg, Virginia, U.S.A.
