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63-443: The supercontinent Rodinia began to break up 870–845  Ma probably as a consequence of a superplume caused by mantle slab avalanches along the margins of the supercontinent. In a second episode c. 750  Ma the western half of Rodinia started to rift apart: western Kalahari and South China broke away from the western margins of Laurentia ; and by 720  Ma Australia and East Antarctica had also separated. In

126-455: A Precambrian supercontinent, which they named "Pangaea I." It was renamed "Rodinia" by McMenamin & McMenamin 1990 , who also were the first to produce a plate reconstruction and propose a temporal framework for the supercontinent. Rodinia formed at c. 1.23 Ga by accretion and collision of fragments produced by breakup of an older supercontinent, Columbia , assembled by global-scale 2.0–1.8 Ga collisional events. Rodinia broke up in

189-408: A phylum or class of Rhizarian protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly an external shell (called a " 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

252-466: A test , or shell, which can have either one or multiple chambers, some becoming quite elaborate in structure. These shells are commonly made of calcium carbonate ( CaCO 3 ) or agglutinated sediment particles. Over 50,000 species are recognized, both living (6,700–10,000) and fossil (40,000). They are usually less than 1 mm in size, but some are much larger, the largest species reaching up to 20 cm. In modern scientific English,

315-586: A Panthalassa Equatorial Counter Current. In the southern Panthalassa, the four currents of the subtropical gyre, the South Panthalassa Gyre, rotated counterclockwise. The South Equatorial Panthalassa Current flowed westward between the Equator and 10°S into the western, intense South Panthalassa Current. The South Polar Current then completed the gyre as the Southwestern Gondwana Current. Near

378-556: A host of larger organisms, including invertebrates, fish, shorebirds, and other foraminifera. It has been suggested, however, that in some cases predators may be more interested in the calcium from foram shells than in the organisms themselves. Several aquatic snail species are known to selectively feed upon foraminifera, often even preferring individual species. Certain benthic foraminifera have been found to be capable of surviving anoxic conditions for over 24 hours, indicating that they are capable of selective anaerobic respiration . This

441-627: A large amount of sea-water into continental ice. Seamounts accreted in eastern Australia as parts of the New England orogen reveal the hotspot history of Panthalassa. From the Late Devonian to the Carboniferous, Gondwana and Panthalassa converged along the eastern margin of Australia along a west-dipping subduction system, which produced (west to east) a magmatic arc, a forearc basin, and an accretionary wedge. Subduction ceased along that margin in

504-653: A major group within the Protozoa known as the Rhizaria . Prior to the recognition of evolutionary relationships among the members of the Rhizaria, the Foraminifera were generally grouped with other amoeboids as phylum Rhizopodea (or Sarcodina) in the class Granuloreticulosa. The Rhizaria are problematic, as they are often called a "supergroup", rather than using an established taxonomic rank such as phylum . Cavalier-Smith defines

567-920: A near-static position between 750 and 633 Ma. This latter solution predicts that break-up was confined to the Ediacaran period and produced the dramatic environmental changes that characterised the transition between the Precambrian and Phanerozoic . However, this theory has been widely criticized, as incorrect applications of paleomagnetic data have been pointed out. In 2009 UNESCO's International Geoscience Programme project 440, named "Rodinia Assembly and Breakup," concluded that Rodinia broke up in four stages between 825 and 550 Ma: The Rodinia hypothesis assumes that rifting did not start everywhere simultaneously. Extensive lava flows and volcanic eruptions of Neoproterozoic age are found on most continents, evidence for large scale rifting about 750 Ma. As early as 850 to 800 Ma,

630-467: A nerve tube. Alcide d'Orbigny , in his 1826 work, considered them to be a group of minute cephalopods and noted their odd morphology, interpreting the pseudopodia as tentacles and noting the highly reduced (in actuality, absent) head. He named the group foraminifères , or "hole-bearers", as members of the group had holes in the divisions between compartments in their shells, in contrast to nautili or ammonites . The protozoan nature of foraminifera

693-709: A now extinct order of single-celled organisms, diversified extensively and developed gigantism —the genus Eopolydiexodina , for example, reached up to 16 cm (6.3 in) in size—and structural sophistication, including symbiont relationships with photosynthesising algae, during the Late Carboniferous and Permian, in what is known as the Carboniferous-Earliest Permian Biodiversification Event . The Capitanian mass extinction event c. 260  Ma , however, put an end to that development, with only dwarf taxa persisting throughout

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756-669: A rift developed between the continental masses of present-day Australia, East Antarctica, India and the Congo and Kalahari cratons on one side and later Laurentia, Baltica, Amazonia and the West African and Rio de la Plata cratons on the other. This rift developed into the Adamastor Ocean during the Ediacaran . Around 550 Ma, near the boundary between the Ediacaran and Cambrian, the first group of cratons fused again with Amazonia, West Africa and

819-400: A single opening or through many perforations in the test. Individual pseudopods characteristically have small granules streaming in both directions. Foraminifera are unique in having granuloreticulose pseudopodia ; that is, their pseudopodia appear granular under the microscope; these pseudopodia are often elongate and may split and rejoin each other. These can be extended and retracted to suit

882-449: Is also common in the group, and at least some species can take advantage of dissolved organic carbon . A few foram species are parasitic , infecting sponges, molluscs, corals, or even other foraminifera. Parasitic strategies vary; some act as ectoparasites, using their pseudopodia to steal food from the host, while others burrow through the shell or body wall of their host to feed on its soft tissue. Foraminifera are themselves eaten by

945-785: Is associated with the North Panthalassa High, which created Ekman convergence between 15°N and 50°N and Ekman divergence between 5°N and 10°N. A pattern developed that resulted in Sverdrup transport that went northward in divergence regions and southward in convergence regions. Western boundary currents resulted in an anti-cyclonic subtropical North Panthalassa gyre at mid-latitudes and a meridional anti-cyclonic circulation centred on 20°N. In tropical northern Panthalassa, trade winds created westward flows while equatorward flows were created by westerlies at higher latitudes. Consequently, trade winds moved water away from Gondwana towards Laurasia in

1008-536: Is interpreted as an adaptation to survive changing oxygenic conditions near the sediment-water interface. Foraminifera are found in the deepest parts of the ocean such as the Mariana Trench , including the Challenger Deep , the deepest part known. At these depths, below the carbonate compensation depth , the calcium carbonate of the tests is soluble in water due to the extreme pressure. The Foraminifera found in

1071-415: Is recognizable as being Elphidium . Early workers classified foraminifera within the genus Nautilus , noting their similarity to certain cephalopods . It was recognised by Lorenz Spengler in 1781 that foraminifera had holes in the septa, which would eventually grant the group its name. Spengler also noted that the septa of foraminifera arced the opposite way from those of nautili and that they lacked

1134-749: Is subducted and the ocean ridge that separated them probably subducted c. 60–55  Ma . Today, the region is dominated by the collision of the Australian Plate with a complex network of plate boundaries in south-east Asia, including the Sundaland block. Spreading along the Pacific-Phoenix ridge ended 83 Ma at the Osbourn Trough at the Tonga - Kermadec Trench . During the Permian, atolls developed near

1197-728: The Grenville orogeny in North America and the Dalslandian orogeny in Europe. Since then, many alternative reconstructions have been proposed for the configuration of the cratons in this supercontinent. Most of these reconstructions are based on the correlation of the orogens on different cratons. Though the configuration of the core cratons in Rodinia is now reasonably well known, recent reconstructions still differ in many details. Geologists try to decrease

1260-530: The green algae , red algae , golden algae , diatoms , and dinoflagellates . These mixotrophic foraminifers are particularly common in nutrient-poor oceanic waters. Some forams are kleptoplastic , retaining chloroplasts from ingested algae to conduct photosynthesis . Most foraminifera are heterotrophic, consuming smaller organisms and organic matter; some smaller species are specialised feeders on phytodetritus , while others specialise in consuming diatoms. Some benthic forams construct feeding cysts, using

1323-647: The orogen . Permian to Cretaceous remains of the convergent margin, preserved as fragments in Zealandia ( New Zealand , New Caledonia , and the Lord Howe Rise ), were rifted off Australia during the Late Cretaceous to Early Tertiary break-up of eastern Gondwana and the opening of the Tasman Sea . The Cretaceous Junction Plate, located north of Australia, separated the eastern Tethys from Panthalassa. Panthalassa

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1386-512: The seafloor sediment (i.e., are benthic , with different sized species playing a role within the macrobenthos , meiobenthos , and 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 identified through molecular analysis of small subunit ribosomal DNA . Foraminifera typically produce

1449-514: The 5th century BCE noted them as making up the rock that forms the Great Pyramid of Giza . These are today recognized as representatives of the genus Nummulites . Strabo , in the 1st Century BCE, noted the same foraminifera, and suggested that they were the remains of lentils left by the workers who built the pyramids. Robert Hooke observed a foraminifera under the microscope, as described and illustrated in his 1665 book Micrographia : I

1512-471: The Cretaceous and later. The former margins of the ocean, however, contain allochthonous terranes with preserved Triassic–Jurassic intra-Panthalassic volcanic arcs, including Kolyma–Omolon (northeast Asia), Anadyr–Koryak (east Asia), Oku–Niikappu (Japan), and Wrangellia and Stikinia (western North America). Furthermore, seismic tomography is being used to identify subducted slabs in the mantle from which

1575-658: The Early Jurassic the Pacific Plate opened originating from a triple junction between the Panthalassic Farallon , Phoenix , and Izanagi plates. Panthalassa can be reconstructed based on magnetic lineations and fracture zones preserved in the western Pacific. Most of the oceanic plates that formed the ocean floor of Panthalassa have been subducted and so traditional plate tectonic reconstructions based on magnetic anomalies can therefore be used only for remains from

1638-564: The Equator on the mid-Panthalassic seamounts. As Panthalassa subducted along its western margin during the Triassic and Early Jurassic, those seamounts and palaeo-atolls were accreted as allochthonous limestone blocks and fragments along the Asian margin. One such migrating atoll complex now form a two-kilometre-long (1.2 mi) and 100-to-150-metre-wide (330–490 ft) body of limestone in central Kyushu , south-west Japan. Fusuline foraminifera ,

1701-474: The Foraminifera has varied since Schultze in 1854, who referred to as an order, Foraminiferida. Loeblich (1987) and Tappan (1992) reranked Foraminifera as a class as it is now commonly regarded. The Foraminifera have typically been included in the Protozoa , or in the similar Protoctista or Protist kingdom . Compelling evidence, based primarily on molecular phylogenetics , exists for their belonging to

1764-575: The Late Carboniferous and jumped eastward. From the Late Carboniferous to the Early Permian the New England orogen was dominated by an extensional setting related to a subduction to strike-slip transition. Subduction was re-initiated in the Permian and the granitic rocks of the New England Batholith were produced by a magmatic arc, indicating the presence of an active plate margin along most of

1827-641: The Neoproterozoic break-up of Rodinia. The North American Cordillera is an accretionary orogen , which grew by the progressive addition of allochthonous terranes along this margin from the Late Palaeozoic. Devonian back-arc volcanism reveals how this eastern Panthalassic margin developed into the active margin it still is in the mid-Palaeozoic. Most of the continental fragments , volcanic arcs , and ocean basins added to Laurentia this way contained faunas of Tethyan or Asian affinity. Similar terranes added to

1890-509: The Neoproterozoic, with its continental fragments reassembled to form Pannotia 633–573 Ma. In contrast with Pannotia, little is known about Rodinia's configuration and geodynamic history. Paleomagnetic evidence provides some clues to the paleolatitude of individual pieces of the Earth's crust , but not to their longitude, which geologists have pieced together by comparing similar geologic features, often now widely dispersed. The extreme cooling of

1953-466: The Permian until the final fusuline extinction in the Great Dying c. 252  Ma . Permian fusulines also developed a remarkable provincialism by which fusulines can be grouped into six domains. Because of the large size of Panthalassa, a hundred million years could separate the accretion of different groups of fusulines. Assuming a minimum accretion rate of 3 centimetres per year (1.2 in/year),

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2016-505: The Rhizaria as an infra-kingdom within the kingdom Protozoa. Some taxonomies put the Foraminifera in a phylum of their own, putting them on par with the amoeboid Sarcodina in which they had been placed. Although as yet unsupported by morphological correlates, molecular data strongly suggest the Foraminifera are closely related to the Cercozoa and Radiolaria , both of which also include amoeboids with complex shells; these three groups make up

2079-524: The Rhizaria. However, the exact relationships of the forams to the other groups and to one another are still not entirely clear. Foraminifera are closely related to testate amoebae . The most striking aspect of most foraminifera are their hard shells, or tests. These may consist of one of multiple chambers, and may be composed of protein, sediment particles, calcite, aragonite, or (in one case) silica. Some foraminifera lack tests entirely. Unlike other shell-secreting organisms, such as molluscs or corals ,

2142-607: The Rio de la Plata cratons during the Pan-African orogeny, which caused the development of Gondwana. In a separate rifting event about 610 Ma, the Iapetus Ocean formed. The eastern part of this ocean formed between Baltica and Laurentia, the western part between Amazonia and Laurentia. Because the timeframe of this separation and the partially contemporaneous Pan-African orogeny are difficult to correlate, it might be that all continental mass

2205-452: The breakup of Rodinia onwards. Rodinia is considered to have formed between 1.3 and 1.23 Ga and broke up again before 750 Ma. Rodinia was surrounded by the superocean Mirovia . According to J.D.A. Piper, Rodinia is one of two models for the configuration and history of the continental crust in the latter part of Precambrian times. The other is Paleopangea , Piper's own concept. Piper proposes an alternative hypothesis for this era and

2268-532: The crustal rocks rise up relative to their surroundings. This rising creates areas of higher altitude where the air is cooler and ice is less likely to melt with changes in season, and it may explain the evidence of abundant glaciation in the Ediacaran. The rifting of the continents created new oceans and seafloor spreading , which produces warmer, less dense oceanic crust . Lower-density, hot oceanic crust will not lie as deep as older, cool oceanic lithosphere. In periods with relatively large areas of new lithosphere,

2331-793: The dominant scheme of classification until Tappan and Loeblich's 1964 classification, which placed foraminifera into the general groupings still used today, based on microstructure of the test wall. These groups have been variously moved around according to different schemes of higher-level classification. Pawlowski's (2013) use of molecular systematics has generally confirmed Tappan and Loeblich's groupings, with some being found as polyphyletic or paraphyletic; this work has also helped to identify higher-level relationships among major foraminiferal groups. "Monothalamids" (paraphyletic) Lagenida "Monothalamids" Miliolida Spirillinida "Monothalamids" Xenophyophorea " Textulariida " (paraphyletic) Robertinida Rotaliida The taxonomic position of

2394-490: The exact purpose of these is unclear, but they have been suggested to function as a reservoir of nitrate. Mitochondria are distributed evenly throughout the cell, though in some species they are concentrated under the pores and around the external margin of the cell. This has been hypothesised to be an adaptation to low-oxygen environments. Several species of xenophyophore have been found to have unusually high concentrations of radioactive isotopes within their cells, among

2457-551: The global climate around 717–635 Ma (the so-called Snowball Earth of the Cryogenian period) and the rapid evolution of primitive life during the subsequent Ediacaran and Cambrian periods are thought to have been triggered by the breaking up of Rodinia or to a slowing down of tectonic processes . The idea that a supercontinent existed in the early Neoproterozoic arose in the 1970s, when geologists determined that orogens of this age exist on virtually all cratons . Examples are

2520-666: The highest of any eukaryote. The purpose of this is unknown. Modern Foraminifera are primarily marine organisms, but living individuals have been found in brackish, freshwater and even terrestrial habitats. The majority of the species are benthic , and a further 50 morphospecies are planktonic . This count may, however, represent only a fraction of actual diversity, since many genetically distinct species may be morphologically indistinguishable. Benthic foraminifera are typically found in fine-grained sediments, where they actively move between layers; however, many species are found on hard rock substrates, attached to seaweeds, or sitting atop

2583-729: The idea that multiple different characters must separate taxonomic groups, and as such placed agglutinated and calcareous genera in close relation. This overall scheme of classification would remain until Cushman 's work in the late 1920s. Cushman viewed wall composition as the single most important trait in classification of foraminifera; his classification became widely accepted but also drew criticism from colleagues for being "not biologically sound". Geologist Irene Crespin undertook extensive research in this field, publishing some ninety papers—including notable work on foraminifera—as sole author as well as more than twenty in collaboration with other scientists. Cushman's scheme nevertheless remained

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2646-1004: The increased rainfall may have reduced greenhouse gas levels to below the threshold required to trigger the period of extreme glaciation known as Snowball Earth . Increased volcanic activity also introduced into the marine environment biologically active nutrients, which may have played an important role in the earliest animals' development. [REDACTED] Africa [REDACTED] Antarctica [REDACTED] Asia [REDACTED] Australia [REDACTED] Europe [REDACTED] North America [REDACTED] South America [REDACTED] Afro-Eurasia [REDACTED] Americas [REDACTED] Eurasia [REDACTED] Oceania Foraminifera " Monothalamea " Tubothalamea Globothalamea incertae sedis Foraminifera ( / f ə ˌ r æ m ə ˈ n ɪ f ə r ə / fə- RAM -ə- NIH -fə-rə ; Latin for "hole bearers"; informally called " forams ") are single-celled organisms , members of

2709-639: The location of former Panthalassic subduction zones can be derived. A series of such subduction zones, called Telkhinia, defines two separate oceans or systems of oceanic plates—the Pontus and Thalassa oceans. Named marginal oceans or oceanic plates include (clockwise) Mongol-Okhotsk (now a suture between Mongolia and Sea of Okhotsk), Oimyakon (between Asian craton and Kolyma-Omolon), Slide Mountain Ocean (British Columbia), and Mezcalera (western Mexico). The western margin (modern coordinates) of Laurentia originated during

2772-421: The marine life of its time. In the Cryogenian , Earth experienced large glaciations , and temperatures were at least as cool as today. Substantial parts of Rodinia may have been covered by glaciers or the southern polar ice cap . Low temperatures may have been exaggerated during the early stages of continental rifting. Geothermal heating peaks in crust about to be rifted, and since warmer rocks are less dense,

2835-470: The needs of the cell. The pseudopods are used for locomotion, anchoring, excretion, test construction and in capturing food, which consists of small organisms such as diatoms or bacteria. Aside from the tests, foraminiferal cells are supported by a cytoskeleton of microtubules, which are loosely arranged without the structure seen in other amoeboids. Forams have evolved special cellular mechanisms to quickly assemble and disassemble microtubules, allowing for

2898-512: The northern Laurentia, in contrast, have affinities with Baltica, Siberia, and the northern Caledonies . The latter terranes were probably accreted along the eastern Panthalassa margin by a Caribbean – Scotia -style subduction system. The evolution of the Panthalassa–Tethys boundary is poorly known because little oceanic crust is preserved—both the Izanagi and the conjugate Pacific Ocean floor

2961-618: The northern Panthalassa Equatorial Current. When the western margins of Panthalassa were reached, intense western boundary currents would form the Eastern Laurasia Current. At mid-latitudes, the North Panthalassa Current would bring the water back east where a weak Northwestern Gondwana Current would finally close the gyre. The accumulation of water along the western margin, coupled with the Coriolis effect , would have created

3024-418: The ocean floors come up, causing the sea level to rise. The result was a greater number of shallower seas. The increased evaporation from the oceans' larger water area may have increased rainfall, which in turn increased the weathering of exposed rock. By inputting data on the ratio of stable isotopes O: O into computer models, it has been shown that in conjunction with quick weathering of volcanic rock ,

3087-448: The poles easterlies created a subpolar gyre that rotated clockwise. Rodinia Rodinia (from the Russian родина , rodina , meaning "motherland, birthplace" ) was a Mesoproterozoic and Neoproterozoic supercontinent that assembled 1.26–0.90 billion years ago (Ga) and broke up 750–633 million years ago (Ma). Valentine & Moores 1970 were probably the first to recognise

3150-448: The previous ones. This idea rejects that Rodinia ever existed as a transient supercontinent subject to progressive break-up in the late Proterozoic and instead that this time and earlier times were dominated by a single, persistent "Paleopangaea" supercontinent. As evidence, he suggests an observation that the palaeomagnetic poles from the continental crust assigned to this time conform to a single path between 825 and 633 Ma and latterly to

3213-424: The pseuodopodia to encyst themselves inside of sediment and organic particles. Certain foraminifera prey upon small animals such as copepods or cumaceans ; some forams even predate upon other forams, drilling holes into the tests of their prey. One group, the xenophyophores, has been suggested to farm bacteria within their tests, although studies have failed to find support for this hypothesis. Suspension feeding

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3276-665: The rapid formation and retraction of elongated pseudopodia. In the gamont (sexual form), foraminifera generally have only a single nucleus, while the agamont (asexual form) tends to have multiple nuclei. In at least some species the nuclei are dimorphic, with the somatic nuclei containing three times as much protein and RNA than the generative nuclei. However, nuclear anatomy seems to be highly diverse. The nuclei are not necessarily confined to one chamber in multi-chambered species. Nuclei can be spherical or have many lobes. Nuclei are typically 30-50 μm in diameter. Some species of foraminifera have large, empty vacuoles within their cells;

3339-400: The seamount chains on which those groups evolved would be separated by at least 3,000 km (1,900 mi). Those groups apparently evolved in completely different environments. A significant sea-level drop at the end of the Permian led to the end-Capitanian extinction event . The cause for the extinction is disputed, but a likely candidate is an episode of global cooling, which transformed

3402-562: The sediment surface. The majority of planktonic foraminifera are found in the globigerinina , a lineage within the rotaliida . However, at least one other extant rotaliid lineage, Neogallitellia , seems to have independently evolved a planktonic lifestyle. Further, it has been suggested that some Jurassic fossil foraminifera may have also independently evolved a planktonic lifestyle, and may be members of Robertinida. A number of forams, both benthic and planktonic, have unicellular algae as endosymbionts , from diverse lineages such as

3465-537: The southwest with the Congo and Kalahari cratons ; and in the northeast with Australia , India and eastern Antarctica . The positions of Siberia and North and South China north of the North American craton differ strongly depending on the reconstruction: Little is known about the paleogeography before the formation of Rodinia. Paleomagnetic and geologic data are only definite enough to form reconstructions from

3528-469: The surface by upwelling in the east while the warmest water extended west into the Tethys Ocean. Subtropical gyres dominated the circulation pattern. The two hemispherical belts were separated by the undulating Intertropical Convergence Zone (ITCZ). In northern Panthalassa, there were mid-latitude westerlies north of 60°N with easterlies between 60°N and the Equator. Atmospheric circulation north of 30°N

3591-408: The term foraminifera is both singular and plural (irrespective of the word's Latin derivation), and is used to describe one or more specimens or taxa: its usage as singular or plural must be determined from context. Foraminifera is frequently used informally to describe the group, and in these cases is generally lowercase. The earliest known reference to foraminifera comes from Herodotus , who in

3654-417: The tests of foraminifera are located inside the cell membrane , within the protoplasm . The organelles of the cell are located within the compartment(s) of the test, and the hole(s) of the test allow the transfer of material from the pseudopodia to the internal cell and back. The foraminiferal cell is divided into granular endoplasm and transparent ectoplasm from which a pseudopodial net may emerge through

3717-709: The uncertainties by collecting geological and paleomagnetical data. Most reconstructions show Rodinia's core formed by the North American Craton (the later paleocontinent of Laurentia ), surrounded in the southeast with the East European Craton (the later paleocontinent of Baltica ), the Amazonian Craton and the West African Craton ; in the south with the Río de la Plata and São Francisco cratons ; in

3780-412: Was a hemisphere-sized ocean, much larger than the modern Pacific. It could be expected that the large size would result in relatively simple ocean current circulation patterns, such as a single gyre in each hemisphere, and a mostly stagnant and stratified ocean. Modelling studies, however, suggest that an east–west sea surface temperature (SST) gradient was present in which the coldest water was brought to

3843-490: Was again joined in one supercontinent between roughly 600 and 550 Ma. This hypothetical supercontinent is called Pannotia . Unlike later supercontinents, Rodinia was entirely barren. It existed before complex life colonized on dry land. Based on sedimentary rock analysis, Rodinia's formation happened when the ozone layer was not as extensive as it is now. Ultraviolet light discouraged organisms from inhabiting its interior. Nevertheless, its existence significantly influenced

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3906-513: Was first recognized by Dujardin in 1835. Shortly after, in 1852, d'Orbigny produced a classification scheme, recognising 72 genera of foraminifera, which he classified based on test shape—a scheme that drew severe criticism from colleagues. H.B. Brady 's 1884 monograph described the foraminiferal finds of the Challenger expedition . Brady recognized 10 families with 29 subfamilies, with little regard to stratigraphic range; his taxonomy emphasized

3969-529: Was trying several small and single Magnifying Glasses, and casually viewing a parcel of white Sand, when I perceiv'd one of the grains exactly shap'd and wreath'd like a Shell[...] I view'd it every way with a better Microscope and found it on both sides, and edge-ways, to resemble the Shell of a small Water-Snail with a flat spiral Shell[...] Antonie van Leeuwenhoek described and illustrated foraminiferal tests in 1700, describing them as minute cockles; his illustration

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