Paleozoic Radiolarians Research Articles

Biotic Crises and Giantism of Radiolarian Skeletons in the Late Paleozoic

The phenomenon of giantism and minimalism in the skeleton of Late Paleozoic radiolarians is very unusually and has not yet been studied. However, this is not ugliness, but inherited morphological features, probably reflecting environmental influences and habitats. The analysis of 618 radiolarian skeletons has shown (1) inverse role of giant and small individuals in the Devonian (2% of giants and 11.7% of dwarfs) and Carboniferous–Permian (22.5% of giants and 2.2% of dwarfs); (2) a general trend toward increasing maximum conditional diameter of a conditional cell, which became 11 times greater, changing from 2% in the Devonian to 21.5% in the Carboniferous–Permian. This trend toward increasing size of skeletons and giantism in Late Paleozoic radiolarians could have indicated degeneration and reflected decline of radiolarians before mass extinction at the boundaries of the Devonian and Carboniferous (97.8% of species), Permian and Triassic (99.0% of species).

Historical insights on nearly 130 years of research on Paleozoic radiolarians

Historical insights on nearly 130 years of research on Paleozoic radiolarians

Historical insights on nearly 130 years of research on Paleozoic radiolarians

ABSTRACT This paper summarizes and highlights the history of descriptive genus-level taxonomy on Paleozoic radiolarians grouped in five major phases: 1) initial discoveries in the 1890s; 2) ignored during the first half of the 1900s; 3) renewed interest during the 1950s to 1970s; 4) the “fast” years of the late 1970s to 1990s; and 5) the early 21st century quest for the oldest and significant progress in the late Permian. In the 1890s, radiolarians were identified with certainty by Hinde in Ordovician radiolarian cherts. Following Hinde's great discovery, and after a 50-year dormant period, Deflandre revived the study of Paleozoic radiolarians through his groundbreaking study of Albaillella from Carboniferous phosphatic nodules, combined with his genius for understanding evolutionary implications. Additional important work was conducted in this third phase by Foreman, particularly with respect to the description of the radiolarian internal structures based on material extracted from Devonian carbonate nod...

An illustrated catalogue and revised classification of paleozoic radiolarian genera

The purpose of this paper is to present a revised classification of Paleozoic radiolarians at the genus level in the form of a series of plates displaying the images of the type species of each genus. These photos are supplemented by an indication of the status of the genus decided by an international team of specialists in this fossil group (Chapter “The catalogue”). The catalogue itself is presented by orders and families. It is also possible to find a genus using the alphabetical list or the list according to the classification (Appendices 1 and 2). After some remarks that illustrate the complex task undertaken to reach a consensus, a “guide for users” is proposed.

Apophyses, verticiles, and denticles in skeletons of Late Paleozoic radiolarians of the subfamily Entactiniinae

Morphostructural analysis of secondary skeletal elements, such as apophyses on the main spines and verticiles on the secondary spines of certain Late Paleozoic radiolarians of the subfamily Entactiniinae allow their taxonomic rank to be raised to genus. The presence of denticles on the secondary spines is only evidence of particular species. Three skeleton morphotypes are established: primary morphotype A, verticillate morphotype B, and apophyseal morphotype C. A new species, Entactinia mariannae sp. nov., and two new genera, Apophysiacus gen. nov. with five species, A. ichikawai (Caridroit et De Wever, 1984), A. minuta (Feng, 2007), A. praepycnoclada (Nazarov et Ormiston, 1983), A. pycnoclada (Nazarov et Ormiston, 1985), and A. sakmaraensis (Kozur et Mostler, 1989), and Verticillides gen. nov. with three species, V. nazarovi nom. nov., V. nestellae sp. nov., and V. verticillatus sp. nov., are described.

On the Age of the Ophiolitic Complexes in Northeastern Jiangxi: A Micropaleontological Analysis

The age assignment of cherts from ophiolitic/metamorphic complexes in northeastern Jiangxi is widely regarded as one of the crucial issues in the tectonic interpretation of South China. The ophiolitic and metamorphic complexes in northeastern Jiangxi have been traditionally regarded as part of the Proterozoic “Banxi (=Penhsi) Group” of the Jiangnan Uplift. However, recent reports of Late Paleozoic radiolarians from the rock complexes have caused some researchers to question the traditional interpretation of the tectonic and paleogeographic framework in the region; but other workers are suspicious about these findings. In order to test the validity of the putative radiolarians, we, an interdisciplinary study group including micropaleontologists, tectonic specialists and regional geologists, conducted field investigations and multiple re-samplings of the localities where the reported fossils were collected. Our comprehensive study shows that the chert of the ophiolitic complex and the associated low-grade metamorphic slate yield Mesoproterozoic and Neoproterozoic acritarchs, confirming the traditional view of their age assignment (Proterozoic); on the other hand, no recognizable radiolarian fossils have been discovered therein, thus raising questions about the recently published result of Paleozoic radiolarian findings. Probable causes for the putative radiolarian findings are thus discussed herein. Geochemical characteristics indicate that the chert sedimentation most probably occurred under a continental margin setting.

渥美半島伊良湖岬地域の秩父帯から産する中・古生代放散虫化石

渥美半島伊良湖岬地域の秩父帯から産する中・古生代放散虫化石

Taxonomy and Diversity History of Paleozoic Radiolarians

The Paleozoic Radiolaria, a major zooplankton group with a siliceous skeleton, comprises 147 genera, 29 families, and 5 suborders. The compilation of 270 literatures on secular diversity change of Paleozoic radiolarians clarifies 7 distinct radiolarian extinction events : Event 1 at the Tremadoc/Arenig boundary (Early Ordovician), Event 2 at the Llandovery/ Wenlock boundary (Early Silurian), Event 3 at the Late Ludlow, Event 4 at the Early/Middle Devonian boundary, Event 5 at the Frasnian/Famennian (F/F) boundary, Event 6 at the Devonian/Carboniferous (D/C) boundary, and Event 7 at the Early/Late Carboniferous boundary.The Paleozoic radiolarians are divided into 3 major groups : a spherical-shell group composed of Spumellaria and Entactinaria ; a cylindrical to conical-shell group composed of Albaillellaria and Nassellaria; and, a flattened-shell group composed of Stauraxonaria. The spherical-shell group declined remarkably at Events 1, 2, 3, 4, and 5, while the cylindrical to conical-shell group declined at Events 6 and 7. The spherical-shell group dominated the Late Paleozoic epicontinental realm, while the cylindrical to conical-shell group dominated the pelagic realm. Events 1-5 represent diversity loss of radiolarians in the epicontinental habitat, while Events 6 and 7 represent diversity loss of pelagic inhabitants. Events 6 and 7 coincide with the timings of continental glaciation, suggesting that the decline of the pelagic radiolarians may have been related to global cooling.It is noteworthy that a significant extinction of radiolarians occurred at the F/F boundary (Event 5), although Radiolaria has previously been regarded to have flourished even across the boundary.Events 1 and 4 are the most significant radiolarian extinction events among 7 events, and occurred synchronously with faunal changes of other planktonic biota. Although terrestrial and benthic records suggest minor crises at these events; a global turnover is emphasized for marine planktonic biota.

Pictorial 1 : Range Chart of Major Paleozoic Radiolarians

Pictorial 1 : Range Chart of Major Paleozoic Radiolarians

Archaeospicularia, ordre nouveau de radiolaires : une nouvelle étape pour la classification des radiolaires du Paléozoïque inférieur

Abstract A new radiolarian order — Archaeospicularia — is proposed for some Lower Paleozoic radiolarians previously considered to belong to Spumellaria and to Collodaria. It is characterized by a globular shell made of several spicules which can be free, interlocked, or fused to formed a latticed wall. The present paper gives the definition of this order and proposes a first classification. It is supposed that the Archaeospicularia represents the oldest radiolarian group and that in the Lower Paleozoic it gave rise to the orders Entactinaria, Albaillellaria, and probably Spumellaria by the reduction of the number of initial spicules. The origin of this order and its relationships with other groups of organisms with siliceous skeletons are also briefly discussed.

Early Paleozoic radiolarian biozonation

Current knowledge of early Paleozoic radiolarians permits the recognition of faunal assemblages and zones that constitute a biozonation. This new zonation utilizes robust and relatively common, easily recognized morphotypes. It will facilitate rapid acquisition of previously unavailable age constraints for marine siliceous sedimentary successions in hitherto poorly understood early Paleozoic orogenic collages.

Un nouvel ordre, une nouvelle famille et un nouveau genre de Radiolaires du Paléozoïque : Latentifistularia, Cauletellidae et Cauletella

Since the genus Deflandrella De Wever and Caridroit 1984 is a homonym of Deflandrella Loeblich and Tappan 1961, the new name Cauletella is herein proposed, and the genus is redefined. Consequently, the family name Deflandrellidae De Wever and Caridroit, previously erected, becomes Cauletellidae, and its definiton is emended. This important radiolarian group, typical of the Permian times, is closely related to the families Ruzhencevispongidae Kozur 1980 and Latentifistulidae Nazarov and Ormiston 1983. These Paleozoic radiolarians are characterized by an initial skeleton quite different from that of the other radiolarian orders and are assigned to the new order Latentifistularia, which is herein defined and briefly discussed.

Cambrian Radiolaria from the Georgina Basin, Queensland, Australia

Well-preserved Middle Cambrian radiolarian were recovered from the Beetle Creek Formation, Inca Formation, and Devoncourt Limestone, Georgina Basin, Australia. Unlike previously reported Early Paleozoic radiolarians, these Middle Cambrian Radiolaria have two diagnostic characteristics in common with siliceous sponge spicules that occur in the same faunas: their skeletal elements consist of hollow tubes, and when a spicule is present, all spicular skeletons, including the internal spicule, are point-centered. The faunas contain 6 new genera and 18 new species; most of them have one or more spicular skeletons. Two new families are established. One family has a spherical shell wall with one or more point-centered internal spicule(s); it is named here Archeoentactiniidae n. fam. and consists of three new genera, Archeoentactinia, Fungomacula, and Spongomassa. The other new family, Palaeospiculumidae n. fam., consists of a point-centered spicular skeleton without a spherical shell capsule; the family is composed of the single genus Palaeospiculum n. gen. The taxa belonging to this family might perhaps be considered to be sponge spicule, but they differ from sponge spicule because their skeleton has the same basic structure as in Palaeoscenidiidae, that is, the spicule consists of apical and basal rays. In addition to these genera belonging to the two families, two other genera are present. They are uncommon and are of uncertain taxonomic position at the family level. One of the two, Aitchisonellum n. gen., has a spherical shell without internal spicule, but it belongs to neither Inaniguttidae Nazarov and Ormiston 1984 nor Palaeoactinosphaeridae Noble 1994; it seems to fit best in the informal group of Palaeoactinomiids Holdsworth (1977). The other genus, Protobiramus n. gen., has no typical internal spicule, but consists of a biaxially arranged four-rayed spicule and repeatedly bifurcated branches of those rays; the branch tips are not merged. The difference in faunal compositions among the three Middle Cambrian formations examined is not great: the Beetle Creek Formation, Inca Formation, and Devoncourt Limestone faunas consist of 7, 23, and 8 species, respectively.

三重県鳥羽地域の上部ジュラ系白根崎層中の珪質岩れきから産出した中・古生代放散虫化石

三重県鳥羽地域の上部ジュラ系白根崎層中の珪質岩れきから産出した中・古生代放散虫化石

Late Paleozoic radiolarians from the Bentong‐Raub suture zone, Peninsular Malaysia

Abstract Radiolarians extracted from marine siliceous sediments from the Bentong‐Raub suture zone, Peninsular Malaysia have indicated a range of ages for olistostromal blocks of bedded chert, siliceous argillite and tuffaceous argillite, and chert clasts and lenses within the mélange from the suture zone. Late Devonian (Faniennian), Early Carboniferous (Tournaisian and Viséan) and Early Permian (Wolfcampian and Leonardian) ages are represented by seven radiolarian zones from ten localities along the suture zone. In stratigraphic order these include Holoeciscus 2–3 Assemblage Zones, Albaillella paradoxa Zone, Albaillella dejendrei Zone, Albaillella cartalla Zone, Pseudoalbaillella lomentaria Zone, Albaillella sinuata Zone and Pseudoalbaillella longtanensis Zone. Fifteen genera are represented by 35 species. The range of ages from Late Devonian to Early Permian suggests that an ocean existed between the Sibumasu and East Malaya terranes from at least Late Devonian to late Early Permian time and that closure of the ocean between the two terranes could not have occurred until after late Early Permian time. The range of ages and rock types from different depositional environments, indicate that the Bentong‐Raub suture zone includes a disrupted accretionary complex.

Mesozoic and Paleozoic radiolarians from the chert pebbles of the Lower Cretaceous Sasayama Group in the eastern part of Hyogo Prefecture, Southwest Japan

Mesozoic and Paleozoic radiolarians from the chert pebbles of the Lower Cretaceous Sasayama Group in the eastern part of Hyogo Prefecture, Southwest Japan

Mesozoic and Paleozoic radiolarians from the Kurosegawa Terrane, southwestern Ehime Prefecture, Japan

Mesozoic and Paleozoic radiolarians from the Kurosegawa Terrane, southwestern Ehime Prefecture, Japan

Setting and occurrence of Late Paleozoic radiolarians in the Sylvester allochthon, part of a proto-Pacific ocean floor terrane in the Canadian Cordillera

Late Paleozoic radiolarians have been used to establish th allochthon of the Slide Mountain terrane in British Columbia, and have thereby greatly clarified the geology and tectonic history of the terrane. As the Sylvester radiolarian fauna is limited, age assignments were based on a few distinctive and diagnostic robust forms. Radiolarians occur in cherts from a wide variety of different oceanic sequences that are structurally juxtaposed within the Sylvester allochthon. Like others in a suite of correlative terranes that lie along the length of the Cordillera, the Sylvester allochthon and the radiolarian bearing cherts in it derive from the telescoping together of slices from what was, in the late Paleozoic, a large area of the proto-Pacific ocean.

Experimental evidence for changes during fossilization of radiolarian tests and implications for a model of biomineralization

This paper contains informations of two kinds: (1) observation on the effects of high-temperatures annealing on the organization of opaline radiolarian test that may simulate fossilization processes and (2) an hypothetical model for the processes of formation, preservation and destruction of radiolarian shells in geologic history, based on diverse published reports and observations of heat-treated skeletons. Biomineralization of radiolarian skeletons start with an appearance of some primary amorphous opal globules E (0.06–0.15 μm) on the hexagonal polysaccharide plates of the organic matrix. The finest globules E are grouped together, forming the globule units D (0.2–03 μm), which, in their turn, are united into a globule unit C (0.4–1 μm). The globule units C are grouped into the hexagonal prismatic units B (1–3 μm). The largest mineral units A (3–8 μm) are formed from the units B and pass throughout the whole shell wall. Besides that, every ultrastructural skeleton unit is surrounded by organic lamella. Therefore, the main tenent of biomineralization is corroborated: the existence of any skeleton as a single solid body is provided by the interactions of all ultrastructural skeleton elements through the unmineralized residual organic matrix. A common trend in the fossilization of skeletons is (1) destruction of the covering organic lamellae accompanied by disintegration of skeletons and (2) carbonization (tannage) of the residual organic matrix increasing a skeleton strength and silica transformation in the following successional: opal-opal-tridymite-tridymite-quartz. Initial stages of the secondary alteration of shells can be reconstructed by high-temperature annealing. As a result of experiment recent radiolarian tests were partially destroyed and showed increased pore sizes, thinning of shell wall and transformation of biogenic amorphous globules into opal-tridymite and even prismatic tridymite. The annealing of radiolarian tests from Early Permian outcrops show changing of pore sizes, cracking of skeletons along the largest ultrastructural units and besides that “guttering” of some primary globular shells and secondary crystallizing of others up to prismatic tridymite. Late Paleozoic radiolarians from deep drilling deposits can serve as an example of complete destruction of the carbonized organic lamellae, of an intergrowth of the mineral units and of substitution of prismatic low-temperature tridymite by dipyramidal-prismatic low-temperature quartz. Thus, modifications of SiO 2 possible can show a response to corresponding stages of lithogenesis: sedimentogenesis-diagenesis-early catagenesis-late catagenesis.

Lower Paleozoic radiolarians of Kazakhstan

Radiolarians and inarticulate brachiopods found with them are significant for the stratigraphy of the silicic-volcanogenic rocks that occur widely in Kazakhstan and were until recently thought to be Precambrian. The most important assemblages of radiolarians, and also of inarticulate brachiopods, were extracted from the rocks by chemical preparation that maintained their natural shape and volume. It was possible by this procedure to extract from the Middle Ordovician Bestamak limestones rich assemblages of radiolarians and inarticulate brachiopods similar to the almost synchronous assemblages from North America, Southern Scotland, and the Baltic region, and sharply different from the radiolarians and inarticulate brachiopods of the Early and Late Ordovician. These facts show that radiolarians, and clearly also inarticulate brachiopods, can be used for interregional correlation and subdivision of Lower Paleozoic volcanogenic-silicic deposits in geosynclinal regions. Several new Middle Ordovician species of...