The Ediacaran Period is a geological period that spans 96 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 538.8 Mya. It marks the end of the Proterozoic Eon, and the beginning of the Phanerozoic Eon. It is named after the Ediacara Hills of South Australia.
Pteridinium is an erniettomorph found in a number of Precambrian deposits worldwide. It is a member of the Ediacaran biota.
Charnia is a genus of frond-like lifeforms belonging to the Ediacaran biota with segmented, leaf-like ridges branching alternately to the right and left from a zig-zag medial suture. The genus Charnia was named for Charnwood Forest in Leicestershire, England, where the first fossilised specimen was found. Charnia is significant because it was the first Precambrian fossil to be recognized as such.
Spriggina is a genus of early bilaterian animals whose relationship to living animals is unclear. Fossils of Spriggina are known from the late Ediacaran period in what is now South Australia. Spriggina floundersi is the official fossil emblem of South Australia; it has been found nowhere else.
Vendobionts or Vendozoans (Vendobionta) are a proposed very high-level, extinct clade of benthic organisms that made up of the majority of the organisms that were part of the Ediacaran biota. It is a hypothetical group and at the same time, it would be the oldest of the animals that populated the Earth about 580 million years ago, in the Ediacaran period. They became extinct shortly after the so-called Cambrian explosion, with the introduction of fauna formed by more recognizable groups and more related to modern animals. It is very likely that the whole Ediacaran biota is not a monophyletic clade and not every genus placed in its subtaxa is an animal.
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.
The end-Ediacaran extinction is a mass extinction believed to have occurred near the end of the Ediacaran period, the final period of the Proterozoic eon. Evidence suggesting that such a mass extinction occurred includes a massive reduction in diversity of acritarchs, the sudden disappearance of the Ediacara biota and calcifying organisms, and the time gap before Cambrian organisms "replaced" them. Some lines of evidence suggests that there may have been two distinct pulses of the extinction event, one occurring 550 million years ago and the other 539 million years ago.
Pectinifrons was a rangeomorph, a member of the Ediacara biota found at Mistaken Point, Newfoundland.
Ediacaran type preservation relates to the dominant preservational mode in the Ediacaran period, where Ediacaran organisms were preserved as casts on the surface of microbial mats.
The Erniettomorphs are a form of Ediacaran fossil consisting of rows of airbed-like tubes arranged along a midline with a glide symmetry. Representative genera include Ernietta, Phyllozoon, Pteridinium, Swartpuntia. Undisputed Erniettomorphs were Ediacaran, but the species Erytholus, Rutgersella, and Protonympha, who have by some been included in this group but are by no means clear members, are found through to the Late Devonian. Their affinity is uncertain; they probably form a clade and are most likely a sister group to the rangeomorphs, which bear a similar construction. Placements within the metazoan crown-group have been rebutted, and it is most likely that these peculiar organisms lie in the stem group to the animals. There is no evidence that they possessed a mouth or gut. Because they may have been found in water which was too deep to permit photosynthesis – and in some cases, lived half-buried in sediment, it is speculated that they fed by osmosis from the sea water. Such a lifestyle requires a very high surface area to volume ratio – higher than is observed in fossils. However, this paradox can be resolved if much of the volume of the organisms was not metabolically active. Many Pteridinium fossils are found completely filled with sand; if this sand were present within the organism while it was alive, this would reduce its metabolically active volume enough to make osmotic feeding viable.
The Avalon explosion, named from the Precambrian fauna of the Avalon Peninsula, is a proposed evolutionary radiation in the history of the Animalia, about 575 million years ago in the Ediacaran Period, with the Avalon explosion being one of three eras grouped in this time. This event is believed to have occurred some 33 million years earlier than the Cambrian explosion. Scientists are still unsure of the full extent behind the development of the Avalon explosion. The Avalon explosion resulted in a rapid increase in organism diversity. Many of the animals and plants from the Avalon are found living in deep marine environments and the Flinders Ranges. The first stages of the Avalon explosion were observed through comparatively minimal species.
The Fermeuse Formation is a fossil-bearing Ediacaran geologic formation in Newfoundland.
Parviscopa is a genus of frondose forms characterized in 2008 based on specimens from Newfoundland, Canada. Parviscopa is a member of the Ediacaran biota, and is more specifically part of the Avalon type assemblage, which is from the older part of the Ediacaran and is characterized by deep water deposits.
Frondosity is the property of an organism that normally flourishes with fronds or leaf-like structures.
The petalonamids (Petalonamae) are an extinct group of archaic animals typical of the Ediacaran biota, also called frondomorphs, dating from approximately 635 million years ago to 516 million years ago. They are benthic and motionless animals, that have the shape of leaves, fronds (frondomorphic), feathers or spindles and were initially considered algae, octocorals or sea pens. It is now believed that there are no living descendants of the group, which shares a probable relation to the Ediacaran animals known as Vendozoans.
Trepassia is a 579 million-year-old fossil of Ediacaran rangeomorph. It was first discovered by Guy M. Narbonne, a professor at Queen's University in Ontario, Canada and colleagues in 2009. Three years later, Martin D. Brasier added additional description to Trepassia. The generic name is taken from the French word, trépassés, which translates to "those that have departed forever" and honors the Trepassey community in Newfoundland. It was originally described as Charnia wardi; it was referred under this synonym in a 2016 paper.
Hapsidophyllas is a rare Ediacaran rangeomorph fossil found at Mistaken Point, Newfoundland, Canada. It was first identified by Emily Bamforth and Guy Narbonne in 2009. Its name comes from the Greek words for “a network of leaves.” Because its characteristic flexible leaflet structure is dissimilar to other known rangeomorphs, Bamforth and Narbonne describe it as a new rangeomorph form, called hapsidophyllid. The only other known hapsidophyllid is the Ediacaran frond Frondophyllas grandis, which shares the network-like configuration of leaflets seen in Hapsidophyllas. Currently, the Hapsidophyllas flexibilis holotype resides in its type locality in the Mistaken Point Ecological Reserve, and a cast of the specimen is on display at the Royal Ontario Museum in Toronto, Canada.
