Artigos de revistas: "Paleontology Cambrian"

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Vidal, Gonzalo. "Proterozoic and Cambrian bioevents". Spanish Journal of Palaeontology 13, n.º 3 (27 de fevereiro de 2022): 11. http://dx.doi.org/10.7203/sjp.23973.

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Hinz-Schallreuter, Ingelore. "Ostracodes from the Middle Cambrian of Australia". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 188, n.º 3 (2 de setembro de 1993): 305–26. http://dx.doi.org/10.1127/njgpa/188/1993/305.

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Landing, Ed, e Guy M. Narbonne. "Scenella and “a chondrophorine (medusoid hydrozoan) from the basal Cambrian (Placentian) of Newfoundland”". Journal of Paleontology 66, n.º 2 (março de 1992): 338. http://dx.doi.org/10.1017/s0022336000033837.

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In a recent article, Narbonne et al. (1991) documented that the stratigraphic range of the chondrophorine Kullingia delicata continues above the the uppermost Precambrian (Vendian) into the lowermost Cambrian (Placentian Series) of the Avalonian faunal province. The revised text published in the Journal of Paleontology includes several references to Scenella Billings, 1872, as a Cambrian chondrophorine. This classification is in error and unfortunately serves to reinforce several recent reports that conclude that Scenella is a chondrophorine rather than a helcionacean mollusk.

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Fortey, Richard A. "Late Cambrian trilobites from the Sultanate of Oman". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 194, n.º 1 (28 de novembro de 1994): 25–53. http://dx.doi.org/10.1127/njgpa/194/1994/25.

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Verma, Vishal, Birendra P. Singh, Om N. Bhargava, Ravi S. Chaubey, Radek Mikuláš, Olev Vinn, Subhay K. Prasad, Scott Morrison e Deepak Kumar. "The ichnogenus Psammichnites in the Cambrian of the Zanskar region: biostratigraphic significance in the correlation of Tethyan Himalaya Cambrian sections, India". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 308, n.º 3 (30 de junho de 2023): 247–65. http://dx.doi.org/10.1127/njgpa/2023/1140.

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Jago, James B., e Peter W. Haines. "Recent radiometric dating of some Cambrian rocks in southern Australia: relevance to the Cambrian time scale." Spanish Journal of Palaeontology 13, n.º 3 (27 de fevereiro de 2022): 115. http://dx.doi.org/10.7203/sjp.23984.

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Miller, Randall F. "Location of trace fossils and problematica of George Frederic Matthew from Part W, Treatise on Invertebrate Paleontology". Journal of Paleontology 70, n.º 1 (janeiro de 1996): 169–71. http://dx.doi.org/10.1017/s0022336000023210.

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George frederic matthew studied the geology of eastern Canada during the late 1800's to early 1900's and became an authority on Cambrian paleontology. Matthew advised the Geological Survey of Canada as its Cambrian expert and published over 200 papers spanning topics from Precambrian stromatolites to Pennsylvanian arthropods to archaeology (Miller, 1988a; Landing and Miller, 1988). He described a number of trace fossils and problematica cited in Hantzschel (1975), but the location of some specimens and their status has been uncertain, sometimes considered missing. Most of the specimens have now been located and this paper summarizes their current location.

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Chang, Wen T. "Cambrian biogeography of the Perigondwana Faunal Realm". Spanish Journal of Palaeontology 13, n.º 3 (27 de fevereiro de 2022): 35. http://dx.doi.org/10.7203/sjp.23977.

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Chang, Wen T. "Cambrian correlation within the Perigondwana Faunal Realm". Spanish Journal of Palaeontology 13, n.º 3 (27 de fevereiro de 2022): 23. http://dx.doi.org/10.7203/sjp.23976.

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Waggoner, Ben, e James W. Hagadorn. "An unmineralized alga from the Lower Cambrian of California, USA". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 231, n.º 1 (2 de fevereiro de 2004): 67–83. http://dx.doi.org/10.1127/njgpa/231/2004/67.

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Elicki, Olaf. "Lower Cambrian carbonates from eastern Germany: Palaeontology, stratigraphy and palaeogeography". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 191, n.º 1 (13 de abril de 1994): 69–93. http://dx.doi.org/10.1127/njgpa/191/1994/69.

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Alvaro, J. Javier, Blanca Bauluz, Sebastien Clausen, Lea Devaere, Andres Gil Imaz, Eric Monceret e Daniel Vizcaino. "Stratigraphic review of the Cambrian-Lower Ordovician volcanosedimentary complexes from the northern Montagne Noire, France". Stratigraphy 11, n.º 1 (2014): 83–96. http://dx.doi.org/10.29041/strat.11.1.04.

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The northern Montagne Noire possesses one of the most complete Cambrian-Lower Ordovician successions of West Gondwana. The strata are poorly fossiliferous, metamorphized and disturbed by Variscan tectonism, and their stratigraphic nomenclature dramatically multiplied by the designation of numerous informal units exclusively identifiable in their ownVariscan thrust slices and nappes. This paper presents an updated revision of lithostratigraphic units and volcanic complexes. Special attention is given to crosscutting relationships of the latter and the setting and age of fossiliferous phosphorites, such as the Watsonella crosbyi-bearing phosphatic limestones of the Marcou Formation. This mollusc is key to defining in the next future the Global Standard Cambrian (Terreneuvian) Stage1/Stage2 boundary. The absence of Cadomian tectono-thermal events is documented by meso- and microstructural and metamorphic analyses.

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Kuzmina, T. V., A. A. Ratnovskaya e A. A. Madison. "Lophophore Evolution from the Cambrian to the Present". Paleontological Journal 55, n.º 10 (dezembro de 2021): 1109–40. http://dx.doi.org/10.1134/s0031030121100051.

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Geyer, Gerd, e Michael Streng. "Middle Cambrian pelecypods from the Anti-Atlas, Morocco". Spanish Journal of Palaeontology 13, n.º 3 (27 de fevereiro de 2022): 83. http://dx.doi.org/10.7203/sjp.23980.

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Bordonaro, Osvaldo Luis, e Eladio Liñán Guijarro. "Some middle Cambrian agnostoids from the Precordillera Argentina." Spanish Journal of Palaeontology 9, n.º 1 (10 de agosto de 2022): 105. http://dx.doi.org/10.7203/sjp.24355.

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Braddy, Simon J. "A new arthropod resting trace from the middle Cambrian of Texas". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 309, n.º 3 (29 de setembro de 2023): 291–300. http://dx.doi.org/10.1127/njgpa/2023/1163.

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Luzhnaya, E. A., E. A. Zhegallo, L. V. Zaitseva e A. L. Ragozina. "Problematical Porifera from the Lower Cambrian of Western Mongolia". Палеонтологический журнал, n.º 3 (1 de maio de 2023): 22–34. http://dx.doi.org/10.31857/s0031031x2303011x.

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From the lower part of the Tommotian Stage of the Lower Cambrian of Western Mongolia, ridge Hevte-Tsakhir-Nuruu described a new species of problematical microfossils of the genus Aetholicopalla Conway Morris in Bengtson et al., 1990, whose representatives are sometimes the dominants of the Early Cambrian taphocoenoses. A. grandipora sp. nov. – spheroidal organisms with initially carbonate (?) skeleton; planktonic and benthic forms described; the latter have a variable shape and attachment sites to the bottom substrate. The outer wall of the fossils is perforated, thin, double; the functional implication of the holes is unclear; be present an internal cavity. By mode of existence, these organisms were probably filter feeders. Geochemical analysis of various taphomorphs showed that A. grandipora sp. nov. preserved by phosphate and siliceous mineralization in the early stages of fossilization. The set of recognized characters allows us to attribute Aetholicopalla to the first skeletal Porifera of an unclear taxonomic position; perhaps these were juvenile forms of organisms close to archaeocyates.

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Normile, D. "PALEONTOLOGY: China Clamps Down on Mining to Preserve Cambrian Site". Science 305, n.º 5692 (24 de setembro de 2004): 1893–94. http://dx.doi.org/10.1126/science.305.5692.1893.

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Amireh, B. S., W. Schneider e A. M. Abed. "Diagenesis and burial history of the Cambrian-Cretaceous sandstone series in Jordan." Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 192, n.º 2 (7 de julho de 1994): 151–81. http://dx.doi.org/10.1127/njgpa/192/1994/151.

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Lipps, Jere H. "Neoproterozoic—Cambrian Biological Revolutions". Paleontological Society Papers 10 (novembro de 2004): 1–4. http://dx.doi.org/10.1017/s1089332600002291.

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The Neoproterozoic—Cambrian biological and geological events between 630 to 530 or so million years ago, are among the most fascinating topics in life history today because the first animals appeared and radiated amidst environmental changes of major magnitude. Not only are paleontologists and geologists interested in these events, but so are the general public, biologists, and theologians, among others. Indeed, this interest was manifested in a cover story in Time Magazine (Nash, 1995), another in the National Geographic (Monastersky, 1998), and in newspapers and other outlets. It is an intriguing time period, for most people are interested in our origins-of life itself, of animals, and of humans. The topics of this book then are nearly unique in this respect. The Paleontological Society is therefore pleased to present a Short Course and book summarizing the evidence, interpretations and hypotheses relating to this interval of time, with a focus on the origin and early evolution of the first known animals through a period of about 100 million years. Like all of the Society's Short Course books, this one is designed to provide a current review an important topic in paleontology for college instructors, interested professionals, and students. Such a book cannot cover the topics in great detail, but the authors have provided up-to-date references to additional sources.

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Mayoral, Eduardo, Eladio Liñán, José Antonio Gámez Vintaned, Fernando Muñiz e Rodolfo Gozalo. "Stranded jellyfish in the lowermost Cambrian (Corduban) of Spain". Spanish Journal of Palaeontology 19, n.º 2 (3 de março de 2021): 191. http://dx.doi.org/10.7203/sjp.19.2.20531.

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Luzhnaya, E. A., E. A. Zhegallo, L. V. Zaitseva e A. L. Ragozina. "Problematic Porifera from the Lower Cambrian of Western Mongolia". Paleontological Journal 57, n.º 3 (junho de 2023): 256–69. http://dx.doi.org/10.1134/s0031030123030103.

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Korovnikov, I. V. "New Species of the Genus <i>Oryctocephalus</i> Walcott from the Middle Cambrian of the Siberian Platform". Палеонтологический журнал, n.º 4 (1 de julho de 2023): 54–59. http://dx.doi.org/10.31857/s0031031x23040062.

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Two new species of trilobites of the Oryctocephalus Walcott, 1886 from the Amgan Stage of the Middle Cambrian of the Siberian Platform were described: Oryctocephalus doliformis sp. nov. and O. molodoensis sp. nov. wich were found in the middle part of the Kuonamka Formation in the Molodo and Muna Rivers sections.

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Stricanne, L., Th Servais, N. Talyzina e M. Vanguestaine. "Reevaluation of the Late Cambrian - Early Ordovician acritarch Nellia acifera GOLUB & VOLKOVA." Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 235, n.º 1 (4 de fevereiro de 2005): 87–112. http://dx.doi.org/10.1127/njgpa/235/2005/087.

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Palmer, Allison R. "Why is intercontinental correlation within the Lower Cambrian so difficult?" Spanish Journal of Palaeontology 13, n.º 3 (27 de fevereiro de 2022): 17. http://dx.doi.org/10.7203/sjp.23974.

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Guo, Junfeng, Jian Han, Heyo Van Iten, Zuchen Song, Yaqin Qiang, Wenzhe Wang, Zhifei Zhang e Guoxiang Li. "A ten-faced hexangulaconulariid from Cambrian Stage 2 of South China". Journal of Paleontology 95, n.º 5 (29 de março de 2021): 957–64. http://dx.doi.org/10.1017/jpa.2021.25.

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AbstractHexangulaconulariids (Cambrian stages 1–2) are an extinct group of medusozoan polyps having a biradially symmetrical, fan-shaped periderm that is distinct from those of medusozoan polyps showing three-, four-, five-, or six-fold radial symmetry. Hexangulaconulariids exhibit substantial variation in gross morphology, including variation in the number of faces on each of the two major sides of the periderm. An intermediate taxon of hexangulaconulariids with ten faces (five on each major side) was expected. Here we describe a new hexangulaconulariid, Decimoconularia isofacialis new genus new species from Bed 5 of the Yanjiahe Formation (Cambrian Stage 2) in the Three Gorges area of Hubei Province, China. The new taxon differs from other hexangulaconulariids (Arthrochites, Hexaconularia, and Septuconularia) mainly in possessing a total of ten faces. The two lateral margins are each marked by a ridge in about the apertural half of the periderm and by a collinear furrow in about the apical half, while the five faces on each major side are bounded by a furrow in about the apertural half and by a collinear ridge in about the apical half. Among hexangulaconulariids, Decimoconularia and Septuconularia may be more closely related to each other than either genus is to Arthrochites or Hexaconularia.UUID: http://zoobank.org/ca270a3b-25ee-4d1f-bdeb-91a963370e70

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Álvaro, J. Javier, e Emmanuelle Vennin. "Benthic marine communities recorded in the Cambrian Iberian platform, NE Spain". Palaeontographica Abteilung A 262, n.º 1-3 (30 de julho de 2001): 1–23. http://dx.doi.org/10.1127/pala/262/2001/1.

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Hoegen, J. von, B. Lemme, J. Zielinski e R. Walter. "Cambrian and Lower Ordovician in the Stavelot-Venn Massif A Model for Depositional History". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 171, n.º 1-3 (26 de setembro de 1985): 217–35. http://dx.doi.org/10.1127/njgpa/171/1985/217.

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Holm-Denoma, Christopher S., William A. Matthews, Linda K. Soar, Mark W. Longman e James W. Hagadorn. "Provenance of Devonian–Carboniferous strata of Colorado: The influence of the Cambrian and the Proterozoic". Rocky Mountain Geology 57, n.º 1 (1 de junho de 2022): 1–21. http://dx.doi.org/10.24872/rmgjournal.57.1.1.

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ABSTRACT We report new LA-ICP-MS U–Pb detrital zircon ages and sedimentary petrology of silty to sandy limestones and dolostones, as well as calcareous to dolomitic sandstones of the Devonian–Carboniferous (Mississippian) Chaffee Group. We also report new detrital zircon ages from the late Cambrian Sawatch Quartzite, and a U–Pb zircon crystallization age on a late Mesoproterozoic (1087.9 ± 13.5 Ma) granitoid of underlying basement from the Eagle Basin of northwest Colorado. Grain populations in the Chaffee Group are mostly bimodal. More than 84% of zircons centered around a Paleoproterozoic (ca. 1.78 Ga) mode typical of the Yavapai province that forms much of the basement of Colorado and an early Mesoproterozoic (ca. 1.42 Ga) mode typical of A-type granites that intrude this region. A notable late Mesoproterozoic (ca. 1.08 Ga) mode exists in some Chaffee samples, giving those samples a trimodal detrital zircon age distribution. These bipartite or tripartite detrital zircon age modes exist in Cambrian, Devonian, and Carboniferous strata from paleogeographically adjacent successions, but the correlation between the Chaffee zircons is highest with the region’s basal Cambrian sandstones of the Sawatch Quartzite, Flathead Sandstone, and Ignacio Quartzite, which have similar (ca. 1.08 Ga, 1.43 Ga, 1.70 Ga, respectively) zircon populations, and a paucity of > 1.8 Ga grains. This similarity suggests that most grains in the Chaffee Group derive from recycling of these basal sandstones, and that little sediment was derived directly from thenexposed Precambrian basement highs, from the Wyoming craton to the north, or from Paleoproterozoic arcs and orogens to the west and northeast. Minor Mesoarchean to early Paleoproterozoic (ca. 3.00 to 2.40 Ga) grains exist in the Chaffee Group, an attribute shared by the Late Ordovician Harding Sandstone of Colorado’s Front Range, but that is absent from the region’s underlying Cambrian sandstones—suggesting some recycled mixture of Cambrian and Ordovician sedimentary rocks. No near-depositional age grains are present in the Chaffee Group. The youngest grain is Early Devonian (~417 Ma), > 45 million years (m.y.) older than these strata. Additionally, Paleozoic grains are extremely uncommon (< 0.1%; n = 2,927 grains).

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Demidenko, Yu E. "Microstructure of the Tubes of Cambrian Zooproblematics of the Family Hyolithellidae". Paleontological Journal 55, n.º 5 (setembro de 2021): 477–88. http://dx.doi.org/10.1134/s0031030121050038.

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Ling, Chenchen, Jin Peng, Hui Zhang, Yifan Wang, Yunbin Shao, Quanyi Sun e Qiujun Wang. "Saetaspongia sponges from the Cambrian (Stage 4) Balang Formation of Guizhou, China". Journal of Paleontology 95, n.º 5 (7 de maio de 2021): 944–56. http://dx.doi.org/10.1017/jpa.2021.29.

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AbstractSaetaspongia so far cannot be confidently assigned to any class-level crown group. Clarifying its phylogenetic position requires new information provided by more detailed studies of previously described and/or new material. Some sponge fossils with the typical skeletal architecture of Saetaspongia have recently been recognized in the Cambrian (Stage 4) Balang Biota of Guizhou, China, including S. jianhensis new species and S. cf. S. densa. The new taxon is characterized by the following features: spicules are fine monaxons and are inclined to be loosely to densely arranged into plumose arrays; skeleton is composed primarily of one major plumose bundle, with an uncertain number (perhaps two) of small plumose arrays; and primary skeleton is occasionally interspersed with some irregularly oriented individual spicules. An additional specimen consisting of large monaxons, with plumose structures and overlying irregular coarse monaxons, closely fits the description and illustrations of previously described S. cf. S. densa. By combining information from previous studies and the present research, fossil evidence indicates that the plumose architecture is a critical feature diagnostic of Saetaspongia and that there are no hexactine-based spicules in this genus. The new material from the Balang Biota further supports the notion that Saetaspongia has a protomonaxonid rather than a hexactinellid affinity. Fossil evidence suggests that Saetaspongia had a wide biogeographic distribution during the early Cambrian and the stratigraphic distribution of this genus extends up to Stage 4.UUID: http://zoobank.org/e9ca5e4a-134c-4daa-9266-19085e32614f.

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Nyers, Andor J. "Thorslundella: a proposed early Cambrian protogastropod that secreted a phosphatic shell due to environmental constraints". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 174, n.º 2 (26 de maio de 1987): 171–92. http://dx.doi.org/10.1127/njgpa/174/1987/171.

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Koneva, S. P., e G. T. Ushatinskaya. "New Upper Cambrian Lingulata (Brachiopoda) from the Agyrek mountains (northeastern central Kazakhstan)". Paleontological Journal 42, n.º 2 (março de 2008): 139–48. http://dx.doi.org/10.1134/s0031030108020044.

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Peel, John S., e Sebastian Willman. "Cavity-dwelling microorganisms from the Ediacaran and Cambrian of North Greenland (Laurentia)". Journal of Paleontology 96, n.º 2 (22 de outubro de 2021): 243–55. http://dx.doi.org/10.1017/jpa.2021.96.

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AbstractRecords of diagenetically mineralized, filamentous, cavity-dwelling microorganisms extend back to strata from the early Paleoproterozoic (2400 Ma). In North Greenland (Laurentia), they are first known from the Ediacaran (Neoproterozoic; ca. 600 Ma) Portfjeld Formation of southern Peary Land, in association with a biota similar to that of the Doushantuo Formation of China. The Portfjeld Formation cavity dwellers are compared with more widespread occurrences in Cambrian (Series 2, Stage 4, Miaolingian Series) strata from the same region in which assemblages in postmortal shelter structures within articulated acrotretoid brachiopods and other invertebrates are common. All specimens were recovered by digestion of carbonate samples in weak acids. The described fossils are preserved as mineral encrusted threads but this diagenetic phosphatization unfortunately obscures their biological identity.

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Albanesi, Guillermo L., M. Eugenia Giuliano, Fernanda E. Pacheco, Gladys Ortega e C. Ruben Monaldi. "Conodonts from the Cambrian-Ordovician Boundary in the Cordillera Oriental, NW Argentina". Stratigraphy 12, n.º 3-4 (2016): 237–56. http://dx.doi.org/10.29041/strat.12.4.03.

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The Cambrian-Ordovician boundary in NW Argentinawas originally proposed for the lower upper section of the Cardonal Formation in the Amarilla Creek, Cajas Range, Cordillera Oriental of Jujuy, based on the first appearance of the conodont Cordylodus lindstromi. After the finding of the index fossil Iapetognathus, the intersystemic boundary in this stratigraphic unit was recently verified. Through the upper 42 meters of the Cardonal Formation, which is 160 m in total thickness, conodonts of the Cordylodus lindstromi, Iapetognathus and Cordylodus angulatus zones were recovered. The lower upper section of the formation where is located the referred boundary consists of grey-greenish shales interbedded with calcareous sandstones that represent an upper off-shore environment which deepens upwards. The associated species belong to the genera Acanthodus, Cordylodus, Eoconodontus, Furnishina, Iapetognathus, Orminskia, Phakelodus, Problematoconites, Proconodontus and Teridontus. Importantly, the index species Iapetognathus fluctivagus and I. jilinensis were documented for the region in this study. The conodont species aremostly cosmopolitan, integrating a local fauna that is interpreted as representing the Transitional Faunal Realm of Mid-latitudes in the Cold Water Domain or to the lately defined Southwestern Gondwana Province from the Cold Domain in the Shallow-Sea Realm. The conodont elements exhibit a black color (CAI 5 = 300° and 480°), with a significant alteration caused by a Jurassic-Cretaceous boundary hydrothermal influence.

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Peel, John S., Christian B. Skovsted e Elise Wallet. "Morphology and ecology of the bradoriid arthropods Spinospitella and Nikolarites from the Cambrian (Series 2, Stage 4) of North Greenland (Laurentia)". PalZ 95, n.º 3 (23 de junho de 2021): 413–27. http://dx.doi.org/10.1007/s12542-021-00569-4.

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AbstractTuberculate fragments referred to Nikolarites spasskyi are compared with a complete carapace and other material of Spinospitella from Cambrian Series 2, Stage 4 in North Greenland. The descriptions expand earlier brief records from Laurentia of the two bradoriids, originally described from Siberia and Australia, respectively. The mutually exclusive occurrences of the two taxa indicate ecological control of their distribution in North Greenland. Robust fragments of Nikolarites spasskyi occur in reworked higher energy deposits of the Aftenstjernesø Formation, while thin-walled carapaces of Spinospitella characterise deeper water mudstones within the Buen and Aftenstjernesø formations.

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Wills, Matthew A. "Cambrian and Recent disparity: the picture from priapulids". Paleobiology 24, n.º 2 (1998): 177–99. http://dx.doi.org/10.1666/0094-8373(1998)024[0177:cardtp]2.3.co;2.

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Abstract An understanding of several macroevolutionary trends has been greatly advanced in recent years by a focus on disparity (morphological variety) rather than taxic diversity. A seminal issue has been the nature of the Cambrian Radiation, and the question of whether problematical Cambrian fossils embody a range of anatomical design far exceeding that observed thereafter. Arthropods have hitherto furnished the only case study, revealing comparable levels of Cambrian and Recent disparity. The generality of this observation needs to be tested in other groups, and the priapulid worms provide a well-documented example. Cladistic analysis of morphological characters for priapulids reveals a paraphyletic series of Cambrian taxa below a crown-group of post-Cambrian genera. However, one extant family (the Tubiluchidae) may be more closely related to Cambrian forms or resolve basally. Character-based morphospace analysis demonstrates greater disparity amongst Recent taxa than amongst their Cambrian counterparts. There is relatively little overlap between the regions of morphospace occupied by Cambrian and Recent genera (contrasting with the situation in arthropods). The Tubiluchidae are morphologically intermediate between Cambrian and other Recent families using several measures of phenetic proximity, and they inhabit environments more comparable with their Cambrian cousins. This work confirms the extensive morphological diversification of major clades by the Cambrian but lends no support to models of a post-Cambrian “decimation” of disparity.

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Dai, Tao, Nigel C. Hughes, Xingliang Zhang e Shanchi Peng. "Development of the early Cambrian oryctocephalid trilobite Oryctocarella duyunensis from western Hunan, China". Journal of Paleontology 95, n.º 4 (17 de março de 2021): 777–92. http://dx.doi.org/10.1017/jpa.2020.111.

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AbstractAbundant articulated specimens of the oryctocarine trilobite Oryctocarella duyunensis from the lower Cambrian (Stage 4, Series 2) Balang Formation at the Bulin section in western Hunan Province, South China, permit the description of all meraspid degrees. The maximum number of thoracic segments observed in this collection is 11. Meraspid growth was accompanied by progressive and gradual change in overall form, and this animal showed an homonymously segmented trunk with variation in the number of pygidial segments during ontogeny. Such variation permits a variety of plausible explanations, but a model of successive instars defined by the number of thoracic segments, and in suborder by the number of pygidial segments, is highly unlikely to explain the growth pattern because it would result in the loss of trunk segments between some instars. Degree-based ontogenetic staging is compatible with the variation observed.

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Liñan, Eladio, e Michal Mergl. "Lower and Middle Cambrian brachiopods from the Iberian Chains and Sierra Morena (Spain)". Spanish Journal of Palaeontology 16, n.º 2 (21 de setembro de 2021): 317. http://dx.doi.org/10.7203/sjp.16.2.21607.

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Parsley, R. L. "Evolution, Functional Morphology and Paedomorphism in the Gogiid-Ascocystitid Lineage (Eocrinoidea; Cambrian-Ordovician)". Paleontological Journal 55, n.º 9 (dezembro de 2021): 966–76. http://dx.doi.org/10.1134/s0031030121090100.

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Handkamer, Neal M., Brian R. Pratt e Robert B. MacNaughton. "Biostratigraphy and paleoecology of the trilobite faunas from the Mount Clark and Mount Cap formations (early and middle Cambrian), eastern Mackenzie Mountains, northwestern Canada". Journal of Paleontology 96, S89 (junho de 2022): 1–47. http://dx.doi.org/10.1017/jpa.2022.13.

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AbstractLower and middle Cambrian strata of the eastern Mackenzie Mountains, Northwest Territories, Canada, were deposited in a semi-enclosed basin along the eastern flank of the Mackenzie Arch. The Mount Clark Formation is predominantly composed of nearshore sandstone and is overlain by deeper water siltstone, mudstone, and carbonates of the Mount Cap Formation. The contact between these formations is interpreted as a flooding surface. Trilobite biostratigraphy indicates the presence of the traditional upper Olenellus through Glossopleura zones (Cambrian Series 2, Stage 4–Miaolingian, Wuliuan) and suggests the flooding surface is diachronous, spanning the Dyeran-Delamaran boundary. Above the Olenellus Zone, the Amecephalus arrojosensis-Eokochaspis nodosa Zone, the new Aitkenaspis keelensis Zone, the new Albertelloides mischi Zone, and the Glossopleura walcotti Zone are recognized. Whereas the older zones are comparable to those in other areas of Laurentia, the trilobite faunas in the Albertelloides mischi and Glossopleura walcotti zones show a greater abundance of zacanthoidids and dolichometopids. They also have a lower diversity of ptychoparioids and oryctocephalids, and lack agnostoids, eodiscoids, dorypygids, and ogygopsidids. This suggests that zacanthoidids and dolichometopids were able to tolerate conditions that were unfavorable to the other groups, probably related to semi-restricted conditions in the basin. Four endemic species exhibit characteristics that are considered paedomorphic. This developmental process took place in three separate lineages, suggesting that heterochrony was also environmentally provoked.New taxonomic names are authored by Handkamer and Pratt. New genera are Eobathyuriscus, Sahtuia, Mexicaspidella Aitkenaspis, Dodoella, and Mackenzieaspis. New species are Bolbolenellus dodoensis, Eobathyuriscus mackenziensis, E. macqueeni, Glossopleura youngi, Sahtuia carcajouensis, Aitkenaspis keelensis, Albertelloides eliasi, Dodoella kobayashii, Mackenzieaspis parallelispinosa, and M. divergens.UUID: http://zoobank.org/a10a2470-853c-4ce8-bf62-7de1d2c99fab.

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Repetski, J. E., M. E. Taylor, D. S. Collins, A. R. Palmer, G. D. Wood e R. C. Tobin. "Integrating paleontology, geothermometry, and sedimentology in determining the history of the Reelfoot Basin, southern midcontinent, U.S.A." Paleontological Society Special Publications 6 (1992): 243. http://dx.doi.org/10.1017/s2475262200008030.

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The northeast-trending Reelfoot basin, extending from northeast Arkansas and westernmost Tennessee into southeastern Missouri, southernmost Illinois, and westernmost Kentucky, is geologically, and socioeconomically, significant because it is co-extensive with the New Madrid Seismic Zone, one of the most seismically active areas of the central and eastern United States. The basin has been periodically active from its inception as a rift basin in the Proterozoic to the present and has accumulated up to at least 5,000 m of sediment, including up to at least 1 km of Cretaceous and Tertiary sedimentary strata near the head of the Mississippi Embayment. Structural and stratigraphic interpretations within the subsurface pre-Mesozoic part of the basin have been based almost entirely on geophysical and physical stratigraphic criteria; these interpretations have been loosely constrained due to an extreme sparsity of drillhole data through the Paleozoic sequence. Recent analysis of Cambrian and Ordovician fossils (conodonts, palynomorphs, brachiopods, and trilobites) from cuttings and core from a very few drillholes allows establishment of the beginnings of a verifiable stratigraphy for this part of the sequence. The paleontological data also provide (1) biofacies evidence for interpretations of the depositional setting during part of the Late Cambrian and Early Ordovician interval and (2) thermal maturation data pertaining to the post-depositional geothermal history of these strata.Upper Cambrian phosphatic brachiopods and trilobites provide improved correlations between strata in the basin, the Ozark shelf to the northwest, and the Upper Mississippi River Valley. Cold-water-realm palynomorphs and trilobites from siliciclastic rocks of turbiditic origin in the central part of the Reelfoot basin support an interpretation, based on sedimentary structures in a short interval of core, of a deep-water basinal origin for these strata.Lower Ordovician conodonts provide a biostratigraphy for the carbonate rocks of this part of the sequence; correlations can be made with the shallow-water sequences of the Knox, Prairie du Chien, and Arbuckle Groups, and the Ozark sequence of the adjacent shelf areas to the east, north, and west. The uppermost Lower Ordovician strata in the basin record a short-term incursion of cooler water environments, reflected by the character of both the conodont fauna and the lithofacies. The youngest Paleozoic dates known from the basin south of the Pascola arch are latest Ibexian (Early Ordovician).Thermal alteration indices of both the Cambrian palynomorphs (organic-walled microphytoplankton) and Ordovician conodonts in the deeper parts of the basin, corroborated by fluid inclusion thermometry, vitrinite reflectance, and other geochemical techniques, are of higher values than predicted using any published estimates of overburden burial. These maturation values most likely reflect burial enhanced by the passage of hydrothermal fluids on a regional scale; they place constraints on interpretations of the tectonothermal evolution of the basin.

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Parcha, S. K. "Biostratigraphy of the Middle Cambrian sequences of Spiti Himalaya and its correlation with analogous sequences in Kashmir Himalaya". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 209, n.º 2 (18 de agosto de 1998): 231–46. http://dx.doi.org/10.1127/njgpa/209/1998/231.

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Mergl, M., G. Geyer e A. El Attari. "The billingsellid genus Saccogonum (Brachiopoda) from the Moroccan Cambrian and its significance for the regional geology and stratigraphy". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 209, n.º 3 (7 de setembro de 1998): 273–93. http://dx.doi.org/10.1127/njgpa/209/1998/273.

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Novozhilova, N. V. "Early Cambrian Palaeoscolecidan Sclerites from the Western Limb of the Chekurovka Anticline (Siberian Platform)". Paleontological Journal 56, n.º 2 (abril de 2022): 147–53. http://dx.doi.org/10.1134/s0031030122020095.

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Toniolo, Thiago F., Juliana M. Leme, Dermeval A. Carmo, Thomas R. Fairchild, Luana Morais e Ricardo I. F. Trindade. "Artifacts resembling Ediacaran or Cambrian fossils: how to identify them and avoid their generation". Journal of Micropalaeontology 42, n.º 2 (18 de agosto de 2023): 83–93. http://dx.doi.org/10.5194/jm-42-83-2023.

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Abstract. The generation of artifacts during sample preparation must be considered in paleobiological studies, particularly during the Ediacaran and Cambrian, since such artifacts can assume forms similar to those of cloudinids and other problematic taxa commonly described in samples from these systems. Chemical reactions between hydrogen peroxide and sulfides from the samples can lead to the formation of tubular and vase-shaped structures. The visual description alone does not allow a conclusion about whether their origin is organic or inorganic. In these cases, chemical composition and ultrastructure analysis are tools that help to distinguish artifacts from bona fide fossils. Scanning electron microscopy can be successfully employed to characterize and differentiate fossils from artifacts. The presence or absence of these structures in thin sections is also an essential piece of information to discuss their biogenicity. Furthermore, not using hydrogen peroxide avoids the risk of formation of the artifacts described here.

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Braun, Andreas. "Prospective Lithologies, Techniques and Chances for Microscopic Paleontology at the Vendian/Cambrian Boundary". Gondwana Research 7, n.º 3 (julho de 2004): 675–84. http://dx.doi.org/10.1016/s1342-937x(05)71055-8.

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Popov, Leonid E., Olga I. Nikitina, Tatiana E. Pirogova e Gappar Kh Ergaliev. "Cambrian brachiopods from the area of the former Semipalatinsk nuclear-testing site, Chingiz Ranges, Kazakhstan". PalZ 95, n.º 2 (10 de fevereiro de 2021): 275–90. http://dx.doi.org/10.1007/s12542-020-00540-9.

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Zhang, Xingliang, e Degan Shu. "Current understanding on the Cambrian Explosion: questions and answers". PalZ, 14 de julho de 2021. http://dx.doi.org/10.1007/s12542-021-00568-5.

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AbstractThe Cambrian Explosion by nature is a three-phased explosion of animal body plans alongside episodic biomineralization, pulsed change of generic diversity, body size variation, and progressive increase of ecosystem complexity. The Cambrian was a time of crown groups nested by numbers of stem groups with a high-rank taxonomy of Linnaean system (classes and above). Some stem groups temporarily succeeded while others were ephemeral and underrepresented by few taxa. The high number of stem groups in the early history of animals is a major reason for morphological gaps across phyla that we see today. Most phylum-level clades achieved their maximal disparity (or morphological breadth) during the time interval close to their first appearance in the fossil record during the early Cambrian, whereas others, principally arthropods and chordates, exhibit a progressive exploration of morphospace in subsequent Phanerozoic. The overall envelope of metazoan morphospace occupation was already broad in the early Cambrian though it did not reach maximal disparity nor has diminished significantly as a consequence of extinction since the Cambrian. Intrinsic and extrinsic causes were extensively discussed but they are merely prerequisites for the Cambrian Explosion. Without the molecular evolution, there could be no Cambrian Explosion. However, the developmental system is alone insufficient to explain Cambrian Explosion. Time-equivalent environmental changes were often considered as extrinsic causes, but the time coincidence is also insufficient to establish causality. Like any other evolutionary event, it is the ecology that make the Cambrian Explosion possible though ecological processes failed to cause a burst of new body plans in the subsequent evolutionary radiations. The Cambrian Explosion is a polythetic event in natural history and manifested in many aspects. No simple, single cause can explain the entire phenomenon.

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Liu, Fan, Timothy P. Topper, Luke C. Strotz, Yue Liang, Yazhou Hu, Christian B. Skovsted e Zhifei Zhang. "Morphological disparity and evolutionary patterns of Cambrian hyoliths". Papers in Palaeontology 10, n.º 2 (março de 2024). http://dx.doi.org/10.1002/spp2.1554.

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AbstractHyolitha represent one of the major constituents of the Cambrian Evolutionary Fauna, first appearing in the Terreneuvian and rapidly diversifying soon after. Recent work has both enriched the hyolith fossil record and expanded our understanding of their biology, but studies documenting the evolutionary trajectory of Cambrian hyoliths remain scarce. Here we present the first study of changes in morphological disparity in Cambrian hyoliths over time with the aim of characterizing the evolutionary trajectory of hyoliths throughout their primary period of diversification. Our results show that hyoliths occupied distinct regions of morphospace at different times during the Cambrian, with an expansion in morphospace occupation associated with the increase in hyolith diversity in the early Cambrian. Both the Sinsk Event and multiple abiotic factors led to a decline in hyolith diversity in the Miaolingian, and morphological disparity also contracts in association with this reduction in diversity.

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