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The Precambrian is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic Eon, which is named after Cambria, the Latinized name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time.
The Proterozoic is the third of the four geologic eons of Earth's history, spanning the time interval from 2500 to 538.8 Mya, the longest eon of the Earth's geologic time scale. It is preceded by the Archean and followed by the Phanerozoic, and is the most recent part of the Precambrian "supereon".
Acritarchs are organic microfossils, known from approximately 1800 million years ago to the present. The classification is a catch all term used to refer to any organic microfossils that cannot be assigned to other groups. Their diversity reflects major ecological events such as the appearance of predation and the Cambrian explosion.
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.
The Vindhya Range is a complex, discontinuous chain of mountain ridges, hill ranges, highlands and plateau escarpments in west-central India.
A microfossil is a fossil that is generally between 0.001 mm and 1 mm in size, the visual study of which requires the use of light or electron microscopy. A fossil which can be studied with the naked eye or low-powered magnification, such as a hand lens, is referred to as a macrofossil.
The Statherian Period is the final geologic period in the Paleoproterozoic era and lasted from 1800 Mya to 1600 Mya. Instead of being based on stratigraphy, these dates are defined chronometrically.
The Gunflint chert is a sequence of banded iron formation rocks that are exposed in the Gunflint Range of northern Minnesota and northwestern Ontario along the north shore of Lake Superior. The Gunflint Chert is of paleontological significance, as it contains evidence of microbial life from the Paleoproterozoic. The Gunflint Chert is composed of biogenic stromatolites. At the time of its discovery in the 1950s, it was the earliest form of life discovered and described in scientific literature, as well as the earliest evidence for photosynthesis. The black layers in the sequence contain microfossils that are 1.9 to 2.3 billion years in age. Stromatolite colonies of cyanobacteria that have converted to jasper are found in Ontario. The banded ironstone formation consists of alternating strata of iron oxide-rich layers interbedded with silica-rich zones. The iron oxides are typically hematite or magnetite with ilmenite, while the silicates are predominantly cryptocrystalline quartz as chert or jasper, along with some minor silicate minerals.
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 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 small shelly fauna, small shelly fossils (SSF), or early skeletal fossils (ESF) are mineralized fossils, many only a few millimetres long, with a nearly continuous record from the latest stages of the Ediacaran to the end of the Early Cambrian Period. They are very diverse, and there is no formal definition of "small shelly fauna" or "small shelly fossils". Almost all are from earlier rocks than more familiar fossils such as trilobites. Since most SSFs were preserved by being covered quickly with phosphate and this method of preservation is mainly limited to the late Ediacaran and early Cambrian periods, the animals that made them may actually have arisen earlier and persisted after this time span.
Red algae, or Rhodophyta, make up one of the oldest groups of eukaryotic algae. The Rhodophyta comprises one of the largest phyla of algae, containing over 7,000 recognized species amidst ongoing taxonomic revisions. The majority of species (6,793) are Florideophyceae, and mostly consist of multicellular, marine algae, including many notable seaweeds. Red algae are abundant in marine habitats. Approximately 5% of red algae species occur in freshwater environments, with greater concentrations in warmer areas. Except for two coastal cave dwelling species in the asexual class Cyanidiophyceae, no terrestrial species exist, which may be due to an evolutionary bottleneck in which the last common ancestor lost about 25% of its core genes and much of its evolutionary plasticity.
Girvanella is a fossil thought to represent the calcified sheath of a filamentous cyanobacterium known from the Burgess Shale and other Cambrian fossil deposits. Specimens are also known from the Early Ordovician San Juan Formation, Argentina.
Mongolitubulus is a form genus encapsulating a range of ornamented conical small shelly fossils of the Cambrian period. It is potentially synonymous with Rushtonites, Tubuterium and certain species of Rhombocorniculum, and owing to the similarity of the genera, they are all dealt with herein. Organisms that bore Mongolitubulus-like projections include trilobites, bradoriid arthropods and hallucigeniid lobopodians.
Bangiales is an order of multicellular red algae of the class Bangiophyceae containing the families Bangiaceae, Granufilaceae, and possibly the extinct genus Rafatazmia with one species, Rafatazmia chitrakootensis. They are one of the oldest eukaryotic organisms, possibly dating back to 1.6 billion years old. Many species are used today as food in different cultures worldwide. Their sizes range from microscopic (Bangiomorpha) to up to two meters long. Many of its species are affected by Pythium porphyrae, a parasitic oomycete. Similar to many other species of red algae, they reproduce both asexually and sexually. They can be both filamentous or foliose, and are found worldwide.
The Barberton Greenstone Belt of eastern South Africa contains some of the most widely accepted fossil evidence for Archean life. These cell-sized prokaryote fossils are seen in the Barberton fossil record in rocks as old as 3.5 billion years. The Barberton Greenstone Belt is an excellent place to study the Archean Earth due to exposed sedimentary and metasedimentary rocks.
Susannah M. Porter is an American paleontologist and geobiologist who studies the early evolution of eukaryotes, the early Cambrian fossil record of animals, and the evolution of skeletal biomineralization. She is currently a professor at the University of California, Santa Barbara. Porter is a Fellow of the Paleontological Society. She has received national recognition awards from the Geological Society of America.
A protist is any eukaryotic organism that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor, the last eukaryotic common ancestor, the exclusion of other eukaryotes means that protists do not form a natural group, or clade. Therefore, some protists may be more closely related to animals, plants, or fungi than they are to other protists. However, like algae, invertebrates and protozoans, the grouping is used for convenience.
Ramathallus is a genus of sessile lobate alga that represents a probable stem-Rhodophyte from the Proterozoic. The holotype of Ramathallus lobatus shows a cell structure with finger-like protrusions and a coating of non-cellular apatic. The cells have a dark granular material inside of them. The organism grew by apical growth and possessed pseudoparenchymatous thallus which in turn infer a possible affinity with the Florideophyceae. Many lobate protrusions radiated from the organisms centre composed out of pseudoparenchymatous tissue interpreted as "Cell fountains" made up of variably-sized cells. Ramathallus shares a close morphological similarity with the Ediacaran genera made up of pseudoparenchymatous, lobate fossils from the Doushantuo phosphorites of China.
The Himalayan fossil hoax, or simply the Himalayan hoax, or technically the peripatetic fossils, is a case of scientific misconduct perpetrated by an Indian palaeontologist Vishwa Jit Gupta of Panjab University. Since his doctoral research in the 1960s and following the next two decades, Gupta worked on the geology and fossil record of the Himalayan region, producing hundreds of research publications that were taken as fundamentals to understanding the geological formation of the Himalayas. Australian geologist, John Talent from Macquarie University, had followed Gupta's research and happened to visit the Himalayas where he found that Gupta's fossils did not match the geological settings there. In 1987, in the presence of Gupta at a scientific conference in Canada, Talent publicly displayed that Gupta's fossils were identical to those found in Morocco. Talent and his student Glenn Brock made systematic reanalysis of Gupta's research bringing out the evidence that Gupta had manipulated, faked and plagiarised his data.
References
- ↑ Azmi, R.J. (1998). "Discovery of Lower Cambrian small shelly fossils and brachiopods from the Lower Vindhyan of Son Valley, Central India". Journal of the Geological Society of India. 52 (4).
- ↑ Lewin, R. (1989). "The Case of the "Misplaced" Fossils: A prominent Australian scientist has examined two decades of work on ancient Himalayan geology and alleges it may be the greatest paleontological fraud of all time". Science. 244 (4902): 277–9. doi:10.1126/science.244.4902.277. PMID 17738290.
- ↑ Dalton, Rex; Jayaraman, Killugudi (2009). "Indian fossil find resolves fraud accusations". Nature. doi:10.1038/news.2009.383.
- 1 2 Bengtson, S.; Belivanova, V.; Rasmussen, B.; Whitehouse, M. (2009). "The controversial "Cambrian" fossils of the Vindhyan are real but more than a billion years older" (PDF). Proceedings of the National Academy of Sciences. 106 (19): 7729–34. Bibcode:2009PNAS..106.7729B. doi: 10.1073/pnas.0812460106 . PMC 2683128 . PMID 19416859.
- ↑ Kumar, S. (2009). "Controversy concerning 'Cambrian' fossils from the Vindhyan sediments: a re-assessment" (PDF). Journal of the Palaeontological Society of India. 54 (1): 115–117.
- ↑ Bengtson, Stefan; Sallstedt, Therese; Belivanova, Veneta; Whitehouse, Martin (2017). "Three-dimensional preservation of cellular and subcellular structures suggests 1.6 billion-year-old crown-group red algae". PLOS Biology. 15 (3): e2000735. doi: 10.1371/journal.pbio.2000735 . PMC 5349422 . PMID 28291791.