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End-Ediacaran Mass Extinction
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 and the other . Evidence Biotic evidence Ediacaran organisms During the Ediacaran period, two main groups of organisms are found in the fossil record: the "Ediacaran biota" of soft-bodied organisms, preserved by microbial mats; and calcifying organisms such as '' Cloudina'' and ''Namacalathus'', which had a carbonate skeleton. Because ''both ''these groups disappear abruptly at the end of the Ediacaran period, , their disappearance cannot simply represent the closure of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ediacaran
The Ediacaran ( ) is a geological period of the Neoproterozoic geologic era, Era that spans 96 million years from the end of the Cryogenian Period at 635 Million years ago, Mya to the beginning of the Cambrian Period at 538.8 Mya. It is the last period of the Proterozoic geologic eon, 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 Ediacaran Period is named after the Ediacara Hills of South Australia, where trace fossils of a diverse community of previously unrecognized lifeforms (later named the Ediacaran biota) were first discovered by geologist Reg Sprigg in 1946. Its status as an official geological period was ratified in 2004 by the International Union of Geological Sciences (IUGS), making it the first new geological period declared in 120 years. Although the period took namesake from the Ediacara Hills ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thaumaptilon
''Thaumaptilon'' is a fossil genus of animals from the middle Cambrian Burgess Shale which some authors have compared to members of the Ediacaran biota, generally believed to have disappeared at the start of the Cambrian, . It was up to 20 cm long, and attached itself to the sea floor with a holdfast. Leaf-shaped, ''Thaumaptilon'' had a central axis extending to its tip, with many "ribs" radiating from it, in a similar manner to the ribs of a leaf. These may have had canals connecting them to the axis. One side of its surface was covered in spots, which might have been zooids. ''Thaumaptilon'' is considered important due to its resemblance to some frondose Ediacarans; it was believed to be a relative of forms such as ''Charnia''. A 2020 study suggested that it should be placed in the group Petalonamae along with similar Ediacaran forms. Forms related to ''Charnia'' were once believed to be related to sea-pens (pennatulacean cnidarians), although this hypothesis has been q ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shuram Excursion
The Shuram excursion, or Shuram-Wonoka excursion, is a change in δ13C, or in the ratio of carbon-13 to carbon-12, taking place during the Ediacaran Period. The exact time period of the excursion is debated among scholars, beginning around 573 Ma and ending around 562 or 551 Ma. It was first noticed in the Wonoka Formation in South Australia in 1990 and later in the Clemente Formation of Mexico in 1992 and the Shuram Formation in Oman Oman, officially the Sultanate of Oman, is a country located on the southeastern coast of the Arabian Peninsula in West Asia and the Middle East. It shares land borders with Saudi Arabia, the United Arab Emirates, and Yemen. Oman’s coastline ... in 1993. It is the largest negative δ13C excursion in Earth history, and recovery took 50 million years, although the apparent magnitude of the excursion may be distorted due to meteoric water diagenesis. It is not known what caused the excursion. The Shuram excursion may have played a role in spar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spriggina
''Spriggina'' is a genus of early 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. The organism reached in length and may have been predation, predatory. Its bottom was covered with two rows of tough interlocking plates, while one row covered its top; its front few segments fused to form a "head." The affinity of ''Spriggina'' is unknown; it has been variously classified as an annelid worm, a rangeomorph-like frond, a variant of ''Charniodiscus'', a proarticulatan, an arthropod (perhaps related to the trilobites), or even an extinct phylum. The lack of known segmented legs or limbs, coupled with the presence of glide reflection instead of symmetry, symmetric segments, suggests that an arthropod classification is unlikely despite some superficial resemblance. The genu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dickinsonia
''Dickinsonia'' is a genus of extinct organism that lived during the late Ediacaran period in what is now Australia, China, Russia, and Ukraine. It had a round, bilaterally symmetric body with multiple segments running along it. It could range from a few millimeters to over a meter in length, and likely lived in shallow waters, feeding on the microbial mats that dominated the seascape at the time. As a member of the Ediacaran biota, its relationships to other organisms has been heavily debated. It was initially proposed to be a jellyfish, and over the years has been claimed to be a land-dwelling lichen, placozoan, or even a giant protist. Currently, the most popular interpretation is that it was a seafloor dwelling animal, perhaps a primitive stem group bilaterian, although this is still contentious. Among other Ediacaran organisms, it shares a close resemblance to other segmented forms like '' Vendia'', Yorgia and '' Spriggina'' and has been proposed to be a member of the ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protonympha
''Protonympha'' is a form genus for problematic fossils of Devonian age in New York. It has been of special interest because of its morphological similarity with the iconic Ediacaran fossil ''Spriggina'', and may have been a late surviving vendobiont. Description ''Protonympha'' is a flat, quilted fossil, which has previously been compared with the arm of a starfish or an annelid worm, but lacks a segmented carapace or stereom. Its preservation in sandstone is similar to Ediacaran type preservations. A less-accepted hypothesis claims the organisms were terrestrial fossils like lichen, with hypothetically interpreted rhizoid Rhizoids are protuberances that extend from the lower epidermal cells of bryophytes and algae. They are similar in structure and function to the root hairs of vascular land plants. Similar structures are formed by some fungi. Rhizoids may be un ...-like extensions as possible evidence it may have lived on land or in shallow pools. References De ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rutgersella
''Rutgersella truexi'' is a form species for problematic fossils of Early Silurian age in Pennsylvania. It has been of special interest because of its morphological similarity with the iconic Ediacaran fossil ''Dickinsonia'', and may have been a late surviving vendobiont. Description ''Rutgersella truexi'' is a flat, segmented fossil, with both radial and bilateral symmetry like ''Dickinsonia'', but with a shorter midline. The fossils are pyritized; some internal chambers are filled with chalcedony, so that they are preserved along with proposed "basal rhizines". Controversially, according to Retallack, these observations suggest affinities with lichens, and perhaps the fungal phylum Glomeromycota Glomeromycota (often referred to as glomeromycetes, as they include only one class, Glomeromycetes) are one of eight currently recognized division (mycology), divisions within the Kingdom (biology), kingdom Fungi, with approximately 230 describ ..., a statement not currently ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ventogyrus
''Ventogyrus'' is an Ediacaran fossil found in the White Sea-Arkhangelsk region of Russia. It was first discovered in the Teska member of the Ust'-Pinega formation, in a thick lens of sandstone, originally sand dumped by storm waves that cut a deep channel through the shallow sea bottom where the organisms lived. Many individuals were preserved on top of each other, often torn or in distorted positions. As a result, it was originally thought to have had a "boat shaped" form and to have lived anchored in the sea floor. However, a nearby site discovered later by Mikhail Fedonkin yielded separate specimens which were beautifully preserved in an upright position and showed the internal anatomy. ''Ventogyrus'' is now believed to have lived on or above the sea floor, an egg-shaped organism made of three modules (like the sections of an orange), all connected to a central rod. This three-fold, or triradial, symmetry is not usually found in the living world today, but it is also seen in o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erytholus
''Erytholus'' is a form genus for problematic fossils of Cambrian age in South Australia. It has been of special interest because of its morphological similarity with the Ediacaran fossil ''Ventogyrus'', and may have been a late surviving vendobiont. It could be a slime mold. Description ''Erytholus'' is a globose, chambered fossil, with associated vertical tubular structures. Its preservation in sandstone is similar to the Ediacaran type preservation of the vendobiont ''Ventogyrus''. It is found at depths of within paleosols. Its affinities are uncertain, although it bears a general resemblance to truffles A truffle is the fruiting body of a subterranean ascomycete fungus, one of the species of the genus ''Tuber''. More than one hundred other genera of fungi are classified as truffles including '' Geopora'', '' Peziza'', '' Choiromyces'', and ' .... References Cambrian fossil record Controversial taxa {{Paleo-biota-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swartpuntia
''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. They are preserved in sandstone beds in the Spitzkopf Member from the Nama formation, which lie above an ash ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platysolenites
Platysolenites is a genus of agglutinated foraminifera known from Ediacaran and lower Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovici ... assemblages. Further reading # Platysolenites is shown to extend below the first appearance of P. antiquissimus in the Neoproterozoic-Cambrian boundary stratotype region, SE Newfoundland, and to occur at higher stratigraphic levels in Wales and Finnmark. References External linksHow old are Feraminfern from the University of Bonn. Foraminifera genera Paleozoic life of Newfoundland and Labrador Monothalamea {{foram-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foraminifera
Foraminifera ( ; Latin for "hole bearers"; informally called "forams") are unicellular organism, single-celled organisms, members of a phylum or class (biology), class of Rhizarian protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and other uses; and commonly an external shell (called a "Test (biology), test") of diverse forms and materials. Tests of chitin (found in some simple genera, and ''Textularia'' in particular) are believed to be the most primitive type. Most foraminifera are marine, the majority of which live on or within the seafloor sediment (i.e., are benthos, benthic, with different sized species playing a role within the macrobenthos, meiobenthos, and Benthos, microbenthos), while a smaller number float in the water column at various depths (i.e., are planktonic), which belong to the suborder Globigerinina. Fewer are known from freshwater or brackish conditions, and some very few (nonaquatic) soil species have been id ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
