Rocks belonging to the Early Paleozoic Los Sombreros Formation crop out on the eastern flank of t... more Rocks belonging to the Early Paleozoic Los Sombreros Formation crop out on the eastern flank of the Sierra de Yerba Loca, along the Rio Jachal section. This Formation consists of black shales and turbidites with interbedded limestone boulders near the base of the section. Boulders yield both early Cambrian trilobites and early Ordovician conodonts. Near the top, a thick sequence of dark gray marls and limestones contains an early Middle Cambrian trilobite fauna which is overlain by limestones and calcareous turbidites containing early Llanvirn graptolites and conodonts. On the basis of paleontological and sedimentological evidences this sequence can be interpreted as a series of submarine gravity slides interbedded within a dominantly turbiditic sequence. -from English summary
Although linguliform brachiopods are a common component in the thick and continuous Upper Cambria... more Although linguliform brachiopods are a common component in the thick and continuous Upper Cambrian-Ordovician clastic successions of northwestern Argentina and Bolivia, to date they remain almost unknown. A few species from the Eastern Cordillera (Cordillera Oriental) were described and illustrated by H. J. Harrington more than eighty years ago and their taxonomic placement needs revision. Other forms have been mentioned in the context of taphonomic analyses on the ‘lingulid shell beds’ recorded from different localities of NW Argentina. In this study, we report wellpreserved obolids from a succession of sandstones and siltstones referred to the Humacha Member of the Santa Rosita Formation, which according to the conodonts of the Paltodus deltifer Zone is of mid Tremadocian (Tr2) age. Rhynchonelliform brachiopods are dominated by Nanorthis purmamarcensis Benedetto and Lipanorthis spp. (unpublished). Lingulate brachiopods consist of acrotretids (not included here) and two species of ...
The Broeggeria assemblage is a peculiar brachiopod association that has been recorded mainly from... more The Broeggeria assemblage is a peculiar brachiopod association that has been recorded mainly from Tremadocian black shales of Baltoscandia, the Anglo-Welsh Basin, Nova Scotia, South Urals and Kazakhstan. Here, we report a low diversity brachiopod association dominated by Broggeria omaguaca n. sp. from upper Tremadocian open-shelf mudstones of northwestern Argentina. The dark-grey transgressive muddy interval bearing the Broeggeria assemblage starts with an erosive flooding surface marked by a glauconite-rich bed containing reworked bioclasts, which overlies storm-dominated shoreface sandstones. Lithologic and taphonomic evidence indicates that the fauna from the mudstones represents a palaeocommunity inhabiting oxygen-depleted bottoms. Besides Broeggeria omaguaca, which by far is the more abundant linguloid, the assemblage includes the obolids Palaeoglossa elongata (Harrington) and Libecoviella aff. tilcarensis Benedetto and Muñoz, and the punctate orthide Lipanorthis andinus Benedetto. Associated trilobites are abundant and low diversity, the more common being the large asaphid Asaphellus jujuanus Harrington. Coeval strata exposed in the Santa Victoria area contain rare specimens of Broeggeria omaguaca associated with Leptembolon argentinum Benedetto and Muñoz and Palaeoglossa elongata. Comparable dysoxic black shales of Furongian age bearing the olenid trilobite Parabolina (Neoparabolina) frequens have yielded a monospecific association of Lingulella n. sp. The records of Broeggeria at global scale support its late Cambrian origin in the Anglo-Welsh Basin (Avalonia) and its rapid migration into the Karatau-Naryn terrane (a part of the Kazakhstanian collage). By the early Tremadocian, Broeggeria spread to Belgium and to the neighbouring Megumia terrane, migrating later (mid-late Tremadocian) to Baltica, Southern Urals, Kazakhstanian terranes, Perunica and the Central Andean Basin. By the late Floian/early Dapingian, Broeggeria colonized palaeoequatorial deep shelves (Spitsbergen). Copyright
A shelly fauna from the upper part of the Zapla glacial diamictite includes the lingulate brachio... more A shelly fauna from the upper part of the Zapla glacial diamictite includes the lingulate brachiopod Orbiculoidea radiata Troedsson, the rhynchonelliforms Dalmanella cf. testudinaria (Dalman) and Paromalomena sp., the bivalve Modiolopsis? sp., and the trilobite Dalmanitina subandina Monaldi and Boso. Both taphonomic and paleoecologic data indicate a lack of transport reflecting the original community. The assemblage is closely comparable to the widespread latest Ordovician Hirnantia-Dalmanitina fauna. The Hirnantian age of the Zapla diamictite is further corroborated by the record of the northern Gondwana chitinozoans Spinachitina cf. oulebsiri Paris and Desmochitina minor typica Eisenack. The graptolites and chitinozoans from the overlying Lipe on Formation indicate that the postglacial transgression took place in the earliest Llandovery (Parakidograptus acuminatus Biozone). According to the tectonosedimentary evidence, the Early Silurian age of the Cancañiri and San Gab an diamictites of north ecentral Bolivia and south Peru based on their palynological record is more likely the age of posglacial gravity flows and not that of the glaciation. We support the hypothesis that the weakly lithified glacigenic deposits of Hirnantian age were reworked and redistributed by high-energy marine processes during the postglacial transgression and then transported to the adjacent deep-marine trough. Iron-rich horizons have been recognized in many basins of southern South America reflecting eustatic and paleoclimatic fluctuations. Most of them formed during the early stages of the postglacial transgression at the Ordovician/Silurian transition and are associated with low sedimentation rates and condensed intervals. The mild maritime postglacial climate, the increasing atmospheric CO 2 , and possibly the presence of incipient vegetated areas led to extensive weathering of glacigenic sediments supplying iron into the marine system to form ferruginous deposits. The sea level fall related to the peak of glaciation is recorded by both paleovalley incision and a sharp subaerial to subglacial unconformity. The transgressive systems tract starts with fluvio-estuarine deposits within incised valleys followed by widespread deposition of subtidal to open marine organic-rich shales onlapping regionally the basement rocks. The recognition of key stratigraphic markers (e.g. sequence boundary, flooding surface, ferruginous beds), alongside reliable micro and macropaleontological evidence allow a more accurate correlation between the Central Andean Basin of Peru, Bolivia and NW Argentina, the W Puna region, the Paraguayan and Brazilian sectors of the Paran a Basin, the Precordillera Basin of W Argentina, and the Cape Basin of South Africa.
Los niveles cuspidales de la Formación San Juan en el cordón del Cerro Viejo (NE de Jáchal) corre... more Los niveles cuspidales de la Formación San Juan en el cordón del Cerro Viejo (NE de Jáchal) corresponden a depósitos de rampa carbonática media a distal. Este intervalo, del Darriwiliano inferior, muestra una tendencia general transgresiva variando desde packstones-wackestones microbioclásticos en la parte inferior hasta mudstones nodulares en la parte superior. La mayoría de las capas contienen una rica fauna de braquiópodos rinconelliformes. Las formas dominantes son los plectambonitoideos Ahtiella argentina, Leptella (Petroria) rugosa y Taffia (Chaloupskia) anomala y los ortoideos Paralenorthis vulgaris y Orthidium geniculatum. Otros taxones, tales como Productorthis, Martellia, Inversella (Reinversella) y Sanjuanella plicata, son menos abundantes y están restringidos a ciertos niveles estratigráficos. Para evaluar las posibles relaciones entre el modo de vida de los braquiópodos y las litofacies que los contienen se agruparon en cuatro morfotipos básicos: pedunculados erectos, p...
How to cite Complete issue More information about this article Journal's homepage in redalyc.org ... more How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Non-profit academic project, developed under the open access initiative
Lingulids and siphonotretids (Lingulata) are described from the Ordovician (Floian-Dapingian) Sur... more Lingulids and siphonotretids (Lingulata) are described from the Ordovician (Floian-Dapingian) Suri Formation of the Famatina Basin in western Argentina. This is the first record of lingulate brachiopods from the arc-related volcano-sedimentary rocks of the Famatina Range. The fauna includes the new obolids Famatinobolus cancellatum gen. et sp. nov. and Lithobolus limbatum sp. nov., and the new siphonotretid Chilcatreta lariojana sp. nov. Associated forms are the glosselins Glossella sp. and Rafanoglossa sp., the elkaniid Monobolina sp. nov., and an unnamed new genus of Lingulellotretidae. The biogeographical affinities of the described Famatinan lingulate assemblage are mixed, sharing Chilcatreta and Glossella with the Laurentian-derived Cuyania terrane, Lithobolus and Rafanoglossa with Bohemia, Monobolina with the Anglo-Welsh basin, and a new lingulellotretid with the Celtic assemblages of Wales.
Lingulids and siphonotretids (Lingulata) are described from the Ordovician (Floian-Dapingian) Sur... more Lingulids and siphonotretids (Lingulata) are described from the Ordovician (Floian-Dapingian) Suri Formation of the Famatina Basin in western Argentina. This is the first record of lingulate brachiopods from the arc-related volcano-sedimentary rocks of the Famatina Range. The fauna includes the new obolids Famatinobolus cancellatum gen. et sp. nov. and Lithobolus limbatum sp. nov., and the new siphonotretid Chilcatreta lariojana sp. nov. Associated forms are the glosselins Glossella sp. and Rafanoglossa sp., the elkaniid Monobolina sp. nov., and an unnamed new genus of Lingulellotretidae. The biogeographical affinities of the described Famatinan lingulate assemblage are mixed, sharing Chilcatreta and Glossella with the Laurentian-derived Cuyania terrane, Lithobolus and Rafanoglossa with Bohemia, Monobolina with the Anglo-Welsh basin, and a new lingulellotretid with the Celtic assemblages of Wales.
Middle Ordovician lingulacean, trematid, and craniid brachiopods are described and illustrated fo... more Middle Ordovician lingulacean, trematid, and craniid brachiopods are described and illustrated for the first time from the uppermost part of San Juan Formation limestones of the Precordillera Basin, west-central Argentina. Sampled beds fall within the Ahtiella argentina brachiopod Zone, which, according to associated conodonts, is of early-mid Darriwilian age. The fauna consists of the linguloideans Glossella cuyanica n. sp. and Lingulasma? sp., the discinoidean Trematis sp., the siphonotretid Chilcatreta tubulata n. gen. n. sp., and a conical shell that is referred provisionally to the order Craniida. The linguliforms from the Cuyania (Precordillera) terrane, although still poorly known, display close similarities to those inhabiting low-to-intermediate latitude palaeocontinents, particularly Laurentia and Baltica, in accordance with evidence from rhynchonelliform brachiopods.
The Ordovician sequence of Famatina mountain belt consists of shales overlain by sandstones with ... more The Ordovician sequence of Famatina mountain belt consists of shales overlain by sandstones with interbedded shell beds containing mainly brachiopods, trilobites and pelecypods. Trilobite fauna of the lower shales is composed by Carolinites genacinaca, Oopsites sp., Merlinia zupaya and Ampyx tinogastaensis. The upper coquinas are characte rized by the genera Annamilella, Merlinia, Neseuretus, Desmorthis, Monorthis, Paralenorthis, Famatinorthis, Triloechia, Skenidioides, Redonia and Catamarcaia. Paleontological evidence indicates that the Suri Formation is Middle-Late Arenig in age. From a biogeographical viewpoint, the Neseuretus Fauna of Famatina Range shows affinities with the Northwestern basin of Argentina. The presence of the trilobite Annamitella and associated brachiopods also suggest affinities with the Precordillera basin.
The malvinokaffric genus Clarkeia occurs at many levels and localities in the Los Espejos Formati... more The malvinokaffric genus Clarkeia occurs at many levels and localities in the Los Espejos Formation (Mid-Late Silurian) of the Precordillera belt, west-central Argentina. The abundance and preservation of most populations permit thorough analysis of their external and internal features and their range of variations. Morphometric study, shell growth pattems and external and internal morphology indicate that the genus Clarkeia was represented by four species in the Precordillera basin: C. tambolarensis sp. nov., C. deflexa sp. nov., C. alta sp.nov. and C. bodenbenderi (Kayser). The type species C. antisiensis (dOrbigny), which is redescribed and figured, seems to be restricted to the Silurian of Bolivia.
En esta contribucion se describen ocho generos del Suborden Orthidina (Brachiopoda) del Ordovicic... more En esta contribucion se describen ocho generos del Suborden Orthidina (Brachiopoda) del Ordovicico de la provincia de San Juan. El material estudiado fue coleccionado en distintas secciones de la Formacion San Juan, aflorantes en el area de Cerro Viejo-Huaco (Departamento Jachal). Se han reconocido los siguientes taxones: Orthidium geniculatum n. sp., Orthidium sp., Archaerorthis termalis n. sp., Nanorthis ornatus n.sp., Nanorthis? sp., Paralenorthis vulgaris n. sp., Paralenorthis? sp., Productorthis cienagaensis n. sp., Valcourea cf. V. ventrocarinata (Butts), Phragmorthis sp. y Paurorthis ellipticus n. sp.
The uppermost levels of the Los Espejos Formation (Late Silurian) have yielded a large number of ... more The uppermost levels of the Los Espejos Formation (Late Silurian) have yielded a large number of Cruziana traces. Specifically, we attribute these traces to Cruziana pudica (Hall). A few scattered specirnens of C. cf. uniloba Seilacher were found in the lower part of the Los Espejos Formation.
A brachiopod fauna dominated by Hindella crassa (J. de C. Sowerby), and also including an indeter... more A brachiopod fauna dominated by Hindella crassa (J. de C. Sowerby), and also including an indeterminate pseudolinguloid, Leangella (Leangella) america sp. nov., Eoplectodonta (Eoplectodonta) duplicata (J. de C. Sowerby), Fardenia sp., Glyptorthis vidari (Baarli)., Dolerorthis plicata (J. de C. Sowerby), an indeterminate giraldiellid, Dalmanella sp., and Stegerhynchus pusillum (J. de C. Sowerby), is described from the La Chilca Formation exposed at Mogotes Azules, San Juan Province, Argentina. The age of the fauna is Early Silurian (Llandovery: Rhuddanian) and it is compared with other Rhuddanian brachiopod faunas both from Gondwana and elsewhere. The brachiopod faunas of Gondwana, despite their relatively low diversity, had much in common with those from Laurentia and Avalonia-Baltica, and heralded the cosmopolitanism that prevailed for all of the first half of the Silurian.Se describe una fauna de braquiópodos proveniente de los niveles basales de la Formación La Chilca expuesta en Mogotes Azules, Precordillera Argentina. La misma está integrada por pseudolinguloideos indeterminados, Leangella (Leangella) america sp. nov., Eoplectodonta (Eoplectodonta) duplicata (J. de C. Sowerby), Fardenia sp., Glyptorthis vidari (Baarli), Dolerorthis plicata (J. de C. Sowerby), un giraldiéllido indeterminado, Dalmanella sp. Stegerhynchus pusillum (J. de C. Sowerby). La edad de la fauna es Silúrico temprano (Llandoveriano, Rhuddaniano). Se compara esta asociación con otras faunas coetáneas de Gondwana y otras regiones. Las faunas de braquiópodos rhuddanianos de Gondwana, a pesar de su diversidad relativamente baja, tienen mucho en común con las de Laurentia y Avalonia-Baltica, confirmando el cosmopolitismo que prevaleció en la primera mitad del Silúrico.Fil: Benedetto, Juan Luis Arnaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Cocks, L. Robin M.. The Natural History Museum; Reino Unid
Rocks belonging to the Early Paleozoic Los Sombreros Formation crop out on the eastern flank of t... more Rocks belonging to the Early Paleozoic Los Sombreros Formation crop out on the eastern flank of the Sierra de Yerba Loca, along the Rio Jachal section. This Formation consists of black shales and turbidites with interbedded limestone boulders near the base of the section. Boulders yield both early Cambrian trilobites and early Ordovician conodonts. Near the top, a thick sequence of dark gray marls and limestones contains an early Middle Cambrian trilobite fauna which is overlain by limestones and calcareous turbidites containing early Llanvirn graptolites and conodonts. On the basis of paleontological and sedimentological evidences this sequence can be interpreted as a series of submarine gravity slides interbedded within a dominantly turbiditic sequence. -from English summary
Although linguliform brachiopods are a common component in the thick and continuous Upper Cambria... more Although linguliform brachiopods are a common component in the thick and continuous Upper Cambrian-Ordovician clastic successions of northwestern Argentina and Bolivia, to date they remain almost unknown. A few species from the Eastern Cordillera (Cordillera Oriental) were described and illustrated by H. J. Harrington more than eighty years ago and their taxonomic placement needs revision. Other forms have been mentioned in the context of taphonomic analyses on the ‘lingulid shell beds’ recorded from different localities of NW Argentina. In this study, we report wellpreserved obolids from a succession of sandstones and siltstones referred to the Humacha Member of the Santa Rosita Formation, which according to the conodonts of the Paltodus deltifer Zone is of mid Tremadocian (Tr2) age. Rhynchonelliform brachiopods are dominated by Nanorthis purmamarcensis Benedetto and Lipanorthis spp. (unpublished). Lingulate brachiopods consist of acrotretids (not included here) and two species of ...
The Broeggeria assemblage is a peculiar brachiopod association that has been recorded mainly from... more The Broeggeria assemblage is a peculiar brachiopod association that has been recorded mainly from Tremadocian black shales of Baltoscandia, the Anglo-Welsh Basin, Nova Scotia, South Urals and Kazakhstan. Here, we report a low diversity brachiopod association dominated by Broggeria omaguaca n. sp. from upper Tremadocian open-shelf mudstones of northwestern Argentina. The dark-grey transgressive muddy interval bearing the Broeggeria assemblage starts with an erosive flooding surface marked by a glauconite-rich bed containing reworked bioclasts, which overlies storm-dominated shoreface sandstones. Lithologic and taphonomic evidence indicates that the fauna from the mudstones represents a palaeocommunity inhabiting oxygen-depleted bottoms. Besides Broeggeria omaguaca, which by far is the more abundant linguloid, the assemblage includes the obolids Palaeoglossa elongata (Harrington) and Libecoviella aff. tilcarensis Benedetto and Muñoz, and the punctate orthide Lipanorthis andinus Benedetto. Associated trilobites are abundant and low diversity, the more common being the large asaphid Asaphellus jujuanus Harrington. Coeval strata exposed in the Santa Victoria area contain rare specimens of Broeggeria omaguaca associated with Leptembolon argentinum Benedetto and Muñoz and Palaeoglossa elongata. Comparable dysoxic black shales of Furongian age bearing the olenid trilobite Parabolina (Neoparabolina) frequens have yielded a monospecific association of Lingulella n. sp. The records of Broeggeria at global scale support its late Cambrian origin in the Anglo-Welsh Basin (Avalonia) and its rapid migration into the Karatau-Naryn terrane (a part of the Kazakhstanian collage). By the early Tremadocian, Broeggeria spread to Belgium and to the neighbouring Megumia terrane, migrating later (mid-late Tremadocian) to Baltica, Southern Urals, Kazakhstanian terranes, Perunica and the Central Andean Basin. By the late Floian/early Dapingian, Broeggeria colonized palaeoequatorial deep shelves (Spitsbergen). Copyright
A shelly fauna from the upper part of the Zapla glacial diamictite includes the lingulate brachio... more A shelly fauna from the upper part of the Zapla glacial diamictite includes the lingulate brachiopod Orbiculoidea radiata Troedsson, the rhynchonelliforms Dalmanella cf. testudinaria (Dalman) and Paromalomena sp., the bivalve Modiolopsis? sp., and the trilobite Dalmanitina subandina Monaldi and Boso. Both taphonomic and paleoecologic data indicate a lack of transport reflecting the original community. The assemblage is closely comparable to the widespread latest Ordovician Hirnantia-Dalmanitina fauna. The Hirnantian age of the Zapla diamictite is further corroborated by the record of the northern Gondwana chitinozoans Spinachitina cf. oulebsiri Paris and Desmochitina minor typica Eisenack. The graptolites and chitinozoans from the overlying Lipe on Formation indicate that the postglacial transgression took place in the earliest Llandovery (Parakidograptus acuminatus Biozone). According to the tectonosedimentary evidence, the Early Silurian age of the Cancañiri and San Gab an diamictites of north ecentral Bolivia and south Peru based on their palynological record is more likely the age of posglacial gravity flows and not that of the glaciation. We support the hypothesis that the weakly lithified glacigenic deposits of Hirnantian age were reworked and redistributed by high-energy marine processes during the postglacial transgression and then transported to the adjacent deep-marine trough. Iron-rich horizons have been recognized in many basins of southern South America reflecting eustatic and paleoclimatic fluctuations. Most of them formed during the early stages of the postglacial transgression at the Ordovician/Silurian transition and are associated with low sedimentation rates and condensed intervals. The mild maritime postglacial climate, the increasing atmospheric CO 2 , and possibly the presence of incipient vegetated areas led to extensive weathering of glacigenic sediments supplying iron into the marine system to form ferruginous deposits. The sea level fall related to the peak of glaciation is recorded by both paleovalley incision and a sharp subaerial to subglacial unconformity. The transgressive systems tract starts with fluvio-estuarine deposits within incised valleys followed by widespread deposition of subtidal to open marine organic-rich shales onlapping regionally the basement rocks. The recognition of key stratigraphic markers (e.g. sequence boundary, flooding surface, ferruginous beds), alongside reliable micro and macropaleontological evidence allow a more accurate correlation between the Central Andean Basin of Peru, Bolivia and NW Argentina, the W Puna region, the Paraguayan and Brazilian sectors of the Paran a Basin, the Precordillera Basin of W Argentina, and the Cape Basin of South Africa.
Los niveles cuspidales de la Formación San Juan en el cordón del Cerro Viejo (NE de Jáchal) corre... more Los niveles cuspidales de la Formación San Juan en el cordón del Cerro Viejo (NE de Jáchal) corresponden a depósitos de rampa carbonática media a distal. Este intervalo, del Darriwiliano inferior, muestra una tendencia general transgresiva variando desde packstones-wackestones microbioclásticos en la parte inferior hasta mudstones nodulares en la parte superior. La mayoría de las capas contienen una rica fauna de braquiópodos rinconelliformes. Las formas dominantes son los plectambonitoideos Ahtiella argentina, Leptella (Petroria) rugosa y Taffia (Chaloupskia) anomala y los ortoideos Paralenorthis vulgaris y Orthidium geniculatum. Otros taxones, tales como Productorthis, Martellia, Inversella (Reinversella) y Sanjuanella plicata, son menos abundantes y están restringidos a ciertos niveles estratigráficos. Para evaluar las posibles relaciones entre el modo de vida de los braquiópodos y las litofacies que los contienen se agruparon en cuatro morfotipos básicos: pedunculados erectos, p...
How to cite Complete issue More information about this article Journal's homepage in redalyc.org ... more How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Non-profit academic project, developed under the open access initiative
Lingulids and siphonotretids (Lingulata) are described from the Ordovician (Floian-Dapingian) Sur... more Lingulids and siphonotretids (Lingulata) are described from the Ordovician (Floian-Dapingian) Suri Formation of the Famatina Basin in western Argentina. This is the first record of lingulate brachiopods from the arc-related volcano-sedimentary rocks of the Famatina Range. The fauna includes the new obolids Famatinobolus cancellatum gen. et sp. nov. and Lithobolus limbatum sp. nov., and the new siphonotretid Chilcatreta lariojana sp. nov. Associated forms are the glosselins Glossella sp. and Rafanoglossa sp., the elkaniid Monobolina sp. nov., and an unnamed new genus of Lingulellotretidae. The biogeographical affinities of the described Famatinan lingulate assemblage are mixed, sharing Chilcatreta and Glossella with the Laurentian-derived Cuyania terrane, Lithobolus and Rafanoglossa with Bohemia, Monobolina with the Anglo-Welsh basin, and a new lingulellotretid with the Celtic assemblages of Wales.
Lingulids and siphonotretids (Lingulata) are described from the Ordovician (Floian-Dapingian) Sur... more Lingulids and siphonotretids (Lingulata) are described from the Ordovician (Floian-Dapingian) Suri Formation of the Famatina Basin in western Argentina. This is the first record of lingulate brachiopods from the arc-related volcano-sedimentary rocks of the Famatina Range. The fauna includes the new obolids Famatinobolus cancellatum gen. et sp. nov. and Lithobolus limbatum sp. nov., and the new siphonotretid Chilcatreta lariojana sp. nov. Associated forms are the glosselins Glossella sp. and Rafanoglossa sp., the elkaniid Monobolina sp. nov., and an unnamed new genus of Lingulellotretidae. The biogeographical affinities of the described Famatinan lingulate assemblage are mixed, sharing Chilcatreta and Glossella with the Laurentian-derived Cuyania terrane, Lithobolus and Rafanoglossa with Bohemia, Monobolina with the Anglo-Welsh basin, and a new lingulellotretid with the Celtic assemblages of Wales.
Middle Ordovician lingulacean, trematid, and craniid brachiopods are described and illustrated fo... more Middle Ordovician lingulacean, trematid, and craniid brachiopods are described and illustrated for the first time from the uppermost part of San Juan Formation limestones of the Precordillera Basin, west-central Argentina. Sampled beds fall within the Ahtiella argentina brachiopod Zone, which, according to associated conodonts, is of early-mid Darriwilian age. The fauna consists of the linguloideans Glossella cuyanica n. sp. and Lingulasma? sp., the discinoidean Trematis sp., the siphonotretid Chilcatreta tubulata n. gen. n. sp., and a conical shell that is referred provisionally to the order Craniida. The linguliforms from the Cuyania (Precordillera) terrane, although still poorly known, display close similarities to those inhabiting low-to-intermediate latitude palaeocontinents, particularly Laurentia and Baltica, in accordance with evidence from rhynchonelliform brachiopods.
The Ordovician sequence of Famatina mountain belt consists of shales overlain by sandstones with ... more The Ordovician sequence of Famatina mountain belt consists of shales overlain by sandstones with interbedded shell beds containing mainly brachiopods, trilobites and pelecypods. Trilobite fauna of the lower shales is composed by Carolinites genacinaca, Oopsites sp., Merlinia zupaya and Ampyx tinogastaensis. The upper coquinas are characte rized by the genera Annamilella, Merlinia, Neseuretus, Desmorthis, Monorthis, Paralenorthis, Famatinorthis, Triloechia, Skenidioides, Redonia and Catamarcaia. Paleontological evidence indicates that the Suri Formation is Middle-Late Arenig in age. From a biogeographical viewpoint, the Neseuretus Fauna of Famatina Range shows affinities with the Northwestern basin of Argentina. The presence of the trilobite Annamitella and associated brachiopods also suggest affinities with the Precordillera basin.
The malvinokaffric genus Clarkeia occurs at many levels and localities in the Los Espejos Formati... more The malvinokaffric genus Clarkeia occurs at many levels and localities in the Los Espejos Formation (Mid-Late Silurian) of the Precordillera belt, west-central Argentina. The abundance and preservation of most populations permit thorough analysis of their external and internal features and their range of variations. Morphometric study, shell growth pattems and external and internal morphology indicate that the genus Clarkeia was represented by four species in the Precordillera basin: C. tambolarensis sp. nov., C. deflexa sp. nov., C. alta sp.nov. and C. bodenbenderi (Kayser). The type species C. antisiensis (dOrbigny), which is redescribed and figured, seems to be restricted to the Silurian of Bolivia.
En esta contribucion se describen ocho generos del Suborden Orthidina (Brachiopoda) del Ordovicic... more En esta contribucion se describen ocho generos del Suborden Orthidina (Brachiopoda) del Ordovicico de la provincia de San Juan. El material estudiado fue coleccionado en distintas secciones de la Formacion San Juan, aflorantes en el area de Cerro Viejo-Huaco (Departamento Jachal). Se han reconocido los siguientes taxones: Orthidium geniculatum n. sp., Orthidium sp., Archaerorthis termalis n. sp., Nanorthis ornatus n.sp., Nanorthis? sp., Paralenorthis vulgaris n. sp., Paralenorthis? sp., Productorthis cienagaensis n. sp., Valcourea cf. V. ventrocarinata (Butts), Phragmorthis sp. y Paurorthis ellipticus n. sp.
The uppermost levels of the Los Espejos Formation (Late Silurian) have yielded a large number of ... more The uppermost levels of the Los Espejos Formation (Late Silurian) have yielded a large number of Cruziana traces. Specifically, we attribute these traces to Cruziana pudica (Hall). A few scattered specirnens of C. cf. uniloba Seilacher were found in the lower part of the Los Espejos Formation.
A brachiopod fauna dominated by Hindella crassa (J. de C. Sowerby), and also including an indeter... more A brachiopod fauna dominated by Hindella crassa (J. de C. Sowerby), and also including an indeterminate pseudolinguloid, Leangella (Leangella) america sp. nov., Eoplectodonta (Eoplectodonta) duplicata (J. de C. Sowerby), Fardenia sp., Glyptorthis vidari (Baarli)., Dolerorthis plicata (J. de C. Sowerby), an indeterminate giraldiellid, Dalmanella sp., and Stegerhynchus pusillum (J. de C. Sowerby), is described from the La Chilca Formation exposed at Mogotes Azules, San Juan Province, Argentina. The age of the fauna is Early Silurian (Llandovery: Rhuddanian) and it is compared with other Rhuddanian brachiopod faunas both from Gondwana and elsewhere. The brachiopod faunas of Gondwana, despite their relatively low diversity, had much in common with those from Laurentia and Avalonia-Baltica, and heralded the cosmopolitanism that prevailed for all of the first half of the Silurian.Se describe una fauna de braquiópodos proveniente de los niveles basales de la Formación La Chilca expuesta en Mogotes Azules, Precordillera Argentina. La misma está integrada por pseudolinguloideos indeterminados, Leangella (Leangella) america sp. nov., Eoplectodonta (Eoplectodonta) duplicata (J. de C. Sowerby), Fardenia sp., Glyptorthis vidari (Baarli), Dolerorthis plicata (J. de C. Sowerby), un giraldiéllido indeterminado, Dalmanella sp. Stegerhynchus pusillum (J. de C. Sowerby). La edad de la fauna es Silúrico temprano (Llandoveriano, Rhuddaniano). Se compara esta asociación con otras faunas coetáneas de Gondwana y otras regiones. Las faunas de braquiópodos rhuddanianos de Gondwana, a pesar de su diversidad relativamente baja, tienen mucho en común con las de Laurentia y Avalonia-Baltica, confirmando el cosmopolitismo que prevaleció en la primera mitad del Silúrico.Fil: Benedetto, Juan Luis Arnaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Cocks, L. Robin M.. The Natural History Museum; Reino Unid
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