| 词条 | Mistaken Point Formation |
| 释义 |
| image = spindle.jpg | caption = | type = Formation | age = {{Geological range|565}} (Ediacaran) | period = Ediacaran | prilithology = | otherlithology = | namedfor = | namedby = | region = {{Flag|Newfoundland}} | country = {{Flag|Canada}} | coordinates = | unitof =Conception Group[1] | subunits = | underlies = Trepassey Formation[2] | overlies = Drook Formation[2] | thickness = | extent = | area = | map = Mistaken Point Formation map.svg | map_caption = Outcrop occurrence of the Mistaken Point formation in southeast Newfoundland }} The Mistaken Point Formation is a geologic formation in Newfoundland and Labrador. It is recognized as a Lagerstätte preserving fossils dating back to the Ediacaran period. It contains a stratum dated to {{Ma|565|error=3}}. GeologyMistaken Point Formation includes many fine ash-beds, which are a good source of zircons used in the uranium-lead method of radiometric dating, allowing the site to be confidently dated to approximately 565 million years old. These fine-grained volcanic ash beds also preserve finely detailed fossils.[3][4] FossilsMistaken Point contains the some of the oldest ediacaran biota in an Avalon-type assemblage. They are commonly categorized as Spindle-shaped (Fractofusus), Frond-shaped(Charniodiscus), or Bush-like / Radiating (Bradgatia) in form. Spindles are the most common fossils in the assemblage. Other forms do exist, such as the conical Thectardis. Some of the forms here appear to survive until the extinction of the Ediacaran biota at the base of the Cambrian. The evolutionary history of these forms is unknown, though hypotheses exist.[5] Discovery of Ediacaran fossils in the Avalon PeninsulaIn the summer of 1967, Shiva Balak Misra, an Indian graduate student (1966–69) at Newfoundland's Memorial University discovered a rich assemblage of imprints of soft bodied organisms on the surface of large rock slabs, while mapping the Conception Group of Avalon Peninsula of Newfoundland near Cape Race, at a place called Mistaken Point.[6] These unusual impressions of previously unknown soft-bodied sea animals on the surfaces of argillites (mudstone) included coelenterates and other metazoa of the Ediacarian period, 575 to 560 million years ago.[7] These fossils are records of the oldest known complex life forms that existed anywhere on Earth.[7] Misra was the first to prepare and present a systematic geological map of the region, to classify and describe the rock sequence of the area and to work out the depositional history of the rocks. The description of the fossil assemblage together with their mode of occurrence, the cause of sudden death, ecological conditions and chronological position form part of Misra's detailed thesis submitted for the degree of Master of Science. The discovery was reported in a 1968 letter to Nature.[8] Misra described the Mistaken Point fauna in detail in 1969, in a paper published in the Bulletin of the Geological Society of America.[9] He sorted the fossil assemblage into five groups, namely spindle-shaped, leaf-shaped, round lobate, dendrite like, and radiating. Each group was defined in terms of distribution and form, sub-categories and biological affinity.[6] The geological environment of the fossil-bearing rocks and the ecology of the animals that lived and died in the Conception Sea were described by Misra in two of his subsequent papers published in the Bulletin of the Geological Society of America in 1971[10] and in the Journal of the Geological Society of India in 1981.[3] Mistaken Point Ecological Reserve is a 5.7-square kilometer area of the coast that protects the fossils.[7] The sudden appearance of Ediacaran soft bodied organisms in the Mistaken Point assemblage has been called the ‘Ediacaran Explosion’ or 'Avalon Explosion' [11] See also{{Portal|Earth sciences|Newfoundland and Labrador|Paleontology|}}
References
1. ^{{Cite journal|url=https://www.academia.edu/download/41916560/Horizontal_surface_traces_from_the_Ferme20160202-3945-1jxueem.pdf|title=Horizontal Surface Traces from the Fermeuse Formation, Ferryland (Newfoundland, Canada), and their Place within the Late Ediacaran Ichnological Revolution|author1=A.G. Liu|author2=D. McIlroy|journal=Geological Association of Canada - Special Paper |issue=9|date=September 2014}} 2. ^1 http://geoatlas.gov.nl.ca/Default.htm 3. ^1 {{cite journal | last = Misra | first = S.B. | authorlink = S.B. Misra | date = August 1981 | title = Depositional Environment of the Late Precambrian Fossil-Bearing rocks of Southeastern Newfoundland, Canada | journal = Journal of Geological Society of India | volume = 22 | issue = 8 | url = http://www.geosocindia.org/index.php/jgsi/article/view/64888 | subscription = yes }} 4. ^{{cite journal|last1=Erwin|first1=Douglas|title=Wonderful Ediacarans, Wonderful Cnidarians?|journal=Evolution & Development|volume=10|issue=3|pages=263–4|date=2008|doi=10.1111/j.1525-142X.2008.00234.x|pmid=18460087}} 5. ^{{cite journal|last1=Misra|first1=S.B.|title=ORIGIN AND GROWTH OF THE EDIACARAN FAUNA AT MISTAKEN POINT, NEWFOUNDLAND, CANADA: A HYPOTHESIS|journal=Journal of the Palaeontological Society of India|date=2010|volume=55|issue=2|pages=177–182}} 6. ^1 {{Cite web|url=http://www.ucmp.berkeley.edu/vendian/mistaken.html|title=Mistaken Point, Newfoundland|website=www.ucmp.berkeley.edu|access-date=2017-07-16}} 7. ^1 2 {{cite web | url = http://www.env.gov.nl.ca/env/parks/wer/r_mpe/index.html | title = Mistaken Point Ecological Reserve | publisher = Newfoundland and Labrador, Dept. of Environment and Conservation }} 8. ^{{cite journal | last1 = Anderson | first1 = M. M. | first2 = S. B. | last2 = Misra | author2-link = S.B. Misra | date = 16 November 1968 | title = Fossils found in pre-Cambrian Conception Group of southeastern Newfoundland | journal = Nature | volume = 220 | issue = 5168 | pages = 680–681 | doi = 10.1038/220680a0 }} 9. ^{{cite journal | last = Misra | first = S.B. | authorlink = S.B. Misra | date = November 1969 | title = Late Precambrian(?) fossils from southeastern Newfoundland | journal = Geological Society of America Bulletin | doi = 10.1130/0016-7606(1969)80[2133:LPFFSN]2.0.CO;2 | volume = 80 | issue = 11 | pages = 2133–2140 }} 10. ^{{cite journal | last = Misra | first = S.B. | authorlink = S.B. Misra | date = April 1971 | title = Stratigraphy and Depositional History of Late Precambrian Coelenterate-Bearing Rocks, Southeastern Newfoundland | journal = Geological Society of America Bulletin | doi = 10.1130/0016-7606(1971)82[979:SADHOL]2.0.CO;2 | volume = 82 | issue = 4 | pages = 979–988 }} 11. ^{{cite journal|last1=Shen|first1=Bing|last2=Dong|first2=Lin|last3=Xiao|first3=Shuhai|last4=Kowalewski|first4=Michal|title=The Avalon Explosion: Evolution of Ediacara Morphospace|journal=Science|volume=319|date=2008|issue=5859|pages=81–84|doi=10.1126/science.1150279|pmid=18174439}} 1 : Ediacaran Newfoundland and Labrador |
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