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1. Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America

Author

MARCELA CICHOWOLSKI, N. EMILIO VACCARI, ALEXANDER POHLE, DANIEL A. MORÓN ALFONSO, ROMAIN VAUCHER, and BEATRIZ G. WAISFELD

Subjects
cephalopoda, ellesmeroceratidae, ellesmeroceras, stem cephalopods, tremadocian, ordovician, santa rosita formation, cordillera oriental, Fossil man. Human paleontology, GN282-286.7, Paleontology, QE701-760
Abstract

We describe early Tremadocian (Kainella meridionalis Biozone) cephalopods from the Cordillera Oriental, Jujuy, NW Argentina. They consist of numerous small specimens collected at the Quebrada de Arenal, Trancas section, near the town of Tilcara, in the Alfarcito Member of the Santa Rosita Formation. All but three specimens were assigned to a new species of Ellesmeroceras (Family Ellesmeroceratidae), E. humahuacaensis sp. nov., based on its slightly endogastric curvature, the characteristics of the siphuncle and chambers dimensions. Micro CT scanning of one specimen aided in the description of the apex and facilitated the construction of a 3D model of the species. A single, similar specimen was assigned to Ellesmeroceras sp. pending the availability of additional material. Two specimens differ from the rest, being exogastric with a lower angle of expansion. They are tentatively assigned to Bassleroceras sp. This material indicates that Cambrian and early Tremadocian cephalopods are not as different as previously thought. “Diversification” and “extinction” events during the late Cambrian may be attributed to taxonomic “over-splitting” and taphonomic and/or sampling biases, respectively. These specimens are currently the oldest recorded in the Central Andean Basin and of West Gondwana, and probably represent the first migration of cephalopods into the region, when the water column was still poorly colonized. During the middle Tremadocian, subsequent immigrations and originations of several cephalopod orders accounted for a rise in diversity and expansion into new niches during this interval. Some of these taxa persisted into the middle Floian, at which time, a second increase in diversity is recorded. Ellesmeroceras humahuacaensis sp. nov. is interpreted as a sub-vertical nektobenthic organism.

Published
2023
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2. A dynamic and collaborative database for morphogeometric information of trilobites

Author

Fernanda Serra, Diego Balseiro, Claude Monnet, Enrique Randolfe, Arnaud Bignon, Juan J. Rustán, Valentin Bault, Diego F. Muñoz, N. Emilio Vaccari, Malena Martinetto, Catherine Crônier, and Beatriz G. Waisfeld

Subjects
Science
Abstract

Abstract Modern morphometric-based approaches provide valuable metrics to quantify and understand macroevolutionary and macroecological patterns and processes. Here we describe TriloMorph, an openly accessible database for morpho-geometric information of trilobites, together with a landmark acquisition protocol. In addition to morphological traits, the database contains contextual data on chronostratigraphic age, geographic location, taxonomic information and lithology of landmarked specimens. In this first version, the dataset has broad taxonomic and temporal coverage and comprises more than 55% of all trilobite genera and 85% of families recorded in the Paleobiology Database through the Devonian. We provide a release of geometric morphometric data of 277 specimens linked to published references. Additionally, we established a Github repository for constant input of morphometric data by multiple contributors and present R functions that help with data retrieval and analysis. This is the first attempt of an online, dynamic and collaborative morphometric repository. By bringing this information into a single open database we enhance the possibility of performing global palaeobiological research, providing a major complement to current occurrence-based databases.

Published
2023
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3. Trilobite expansion into estuarine environments during the Ordovician radiation

Author

M. Gabriela Mángano, Luis A. Buatois, Beatriz G. Waisfeld, Diego F. Muñoz, N. Emilio Vaccari, and Ricardo A. Astini

Subjects
trace fossils, asaphids, olenids, marginal-marine environments, brackish water, argentina, Geology, QE1-996.5
Abstract

Trilobites have traditionally been considered fully marine. Through the integration of ichnological, palaeobiological and sedimentological datasets within a sequence-stratigraphic and strati­graphic palaeobiology framework, we challenge this assumption. This analysis is based on the study of incised fluvio-estuarine valley deposits from the Furongian Tilcara Member (TM) and the latest Furongian Pico de Halcón Member (PHM) of the Santa Rosita Formation, the early late Tremadocian Cardonal Formation (CF), and the DapingianâDarriwilian Alto del Cóndor Formation (ACF), from Cordillera Oriental of northwest Argentina. These valleys were incised into wave-dominated shallow-marine strata and filled with transgressive deposits that accumulated in tide-dominated estuaries. Whereas the TM lacks any body or trace fossil evidence of the presence of trilobites in estuarine settings, the other three units reveal that trilobites were able to inhabit these settings. The PHM and CF are host to trilobite trace fossils in outer estuarine facies, both containing various ichnospecies of Cruziana (e.g., C. omanica and C. semiplicata in the TM) and Rusophycus (e.g., R. latus in both units). In addition, the PHM also contains body fossils of the olenid trilobite Neoparabolina frequens argentina in the same deposits in which the trace fossils are preserved, as well as from middle estuarine facies. The ACF displays trilobite trace fossils of the C. rugosa group in inner, middle, and outer estuarine deposits, illustrating further landward incursions. This unit also contains body fossils of the asaphid trilobite Ogyginus sp. Accordingly, our data indicate two attempts of landward exploration via brackish water: phase 1 in which the outer to middle portion of estuaries were colonized by olenids (Furongianâearly late Tremadocian) and phase 2 involving exploration of the inner, middle, and outer estuarine zones by asaphids (DapingianâDarriwilian). Our study indicates that these trilobites were tolerant to salinity stress and able to make use of the ecological advantages offered by marginal-marine environments migrating up-estuary, following salt wedges either reflecting amphidromy or as euryhaline marine wanderers. It is suggested that tolerance to salinity stress arose independently among different trilobite groups as a result of the broad array of behaviors and adaptations of trilobites during the Ordovician radiation. We speculate that the assumption that all trilobites were stenohaline may have resulted in the misinterpretation of some tide-dominated estuarine deposits as fully marine.

Published
2023
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4. Depositional environments and stratigraphy of the Upper Cambrian-lower Ordovician Santa Rosita formation at the Alfarcito area, Cordillera Oriental, Argentina: integration of biostratigraphic data within a sequence stratigraphic framework

Author

Luis A. Buatois, Fernando J. Zeballo, Guillermo L. Albanesi, Gladys Ortega, N. Emilio Vaccari, and M. Gabriela Mángano

Subjects
Facies analysis, Sequence stratigraphy, Biostratigraphy, Shallow marine, Cambrian-Ordovician, Argentina., Geology, QE1-996.5, Geophysics. Cosmic physics, QC801-809
Abstract

The Upper Cambrian-Tremadocian rocks exposed in the Alfarcito area of Cordillera Oriental, northwest Argentina reveal a series of transgressive-regressive cycles punctuated by incision of fluvio-estuarine valleys. An integrated sedimentologic, biostratigraphic and sequence stratigraphic study permits characterization of the sedimentary facies and stratal stacking patterns, and a revision of the stratigraphic framework of this succession. The Upper Cambrian-Tremadocian succession is included within the existing Santa Rosita Formation, which is formally subdivided here into six units, the Tilcara, Casa Colorada, Pico de Halcón, Alfarcito, Rupasca and Humacha members. This scheme recognizes the internal complexities of the formation, in that the Tilcara and Pico de Halcón members record sedimentation in areally-restricted incised valleys and contain structures indicative of tidal dominance, whereas the Casa Colorada, Alfarcito and Rupasca members typify wave-dominated open-marine environments, where background suspension-fallout was punctuated by oscillatory flows during storms. The Tilcara Member is incised into the underlying Mesón Group. The Casa Colorada Member reflects a basinwide Late Cambrian transgression and subsequent progradation and consists of lower to upper offshore deposits. The Pico de Halcón Member is incised into the Casa Colorada Member. The Alfarcito Member is divided into three distinctly upward-coarsening and-thickening intervals. The sandstone-dominated intervals are composed of lower to middle shoreface deposits with minor amounts of offshore transition and upper shoreface deposits. The heterolithic, fine-grained intervals record more distal deposition, ranging from the lower offshore to the offshore transition. The Rupasca Member is a dominantly fine-grained unit that records a major late early to early late Tremadocian transgression. The lower interval of this member consists of lower offshore to offshore-transition deposits, while the upper part is made up of shelf to lower offshore deposits. The Humacha Member is not exposed in the study area. The importance of integrating biostratigraphy within a sedimentologic and sequence-stratigraphic framework is underscored here, in that it enables us to construct a more accurate stratigraphic framework which permits a clear understanding of the sedimentary dynamics of this system.

Published
2021

5. A new Mississippian hexactinellid sponge from the western Gondwana: Taxonomic and paleobiogeographic implications

Author

Marcelo G. Carrera, Juan Jose Rustán, N. Emilio Vaccari, and Miguel Ezpeleta

Subjects
Porifera, Hexactinellida, Reticulosa, Carboniferous, Mississippian, Argentina, Fossil man. Human paleontology, GN282-286.7, Paleontology, QE701-760
Abstract

A Mississippian hexactinellid sponge from the western Argentina improves the extremely poor late Paleozoic sponge records from Gondwana. The sponge is included in the subfamily Thysanodictyinae of family Dictyospongiidae. The new genus and species Minitaspongia parvis is erected, and its well-preserved spicular structure is described in detail representing the first approximation of the spicule assemblage in Thysanodictyinae. The skeleton is clathrate, three-dimensional with at least two ranks of rectangular openings. This first report of this subfamily outside North America represents the best-known hexactinellid and the first dictyosponge record from the Carboniferous of Gondwana. Unlike the occurrences of Thysanodictyinae in North America, with thick skeletons linked to high-energy shallow water settings, Minitaspongia occurs in low-energy water siliciclastic settings related to a cold climate and glacimarine deposits. Accordingly, the complex wall structure of this sponge should not be invoked as a necessary adaptation to high energy and shallow water settings.

Published
2018
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6. Depositional environments and stratigraphy of the Upper Cambrian-lower Ordovician Santa Rosita formation at the Alfarcito area, Cordillera Oriental, Argentina: integration of biostratigraphic data within a sequence stratigraphic framework

Author

Luis A. Buatois, Fernando J. Zeballo, Guillermo L. Albanesi, Gladys Ortega, N. Emilio Vaccari, and M. Gabriela Mangano

Subjects
Análisis de facies, Estratigrafía secuencial, Bioestratigrafía, Marino somero, Cámbrico-Ordovícico, Argentina, Facies analysis, Sequence stratigraphy, Biostratigraphy, Shallow marine, Cambrian-Ordovician, Geology, QE1-996.5, Geophysics. Cosmic physics, QC801-809
Abstract

The Upper Cambrian-Tremadocian rocks exposed in the Alfarcito area of Cordillera Oriental, northwest Argentina reveal a series of transgressive-regressive cycles punctuated by incision of fluvio-estuarine valleys. An integrated sedimentologic, biostratigraphic and sequence stratigraphic study permits characterization of the sedimentary facies and stratal stacking patterns, and a revision of the stratigraphic framework of this succession. The Upper Cambrian-Tremadocian succession is included within the existing Santa Rosita Formation, which is formally subdivided here into six units, the Tilcara, Casa Colorada, Pico de Halcón, Alfarcito, Rupasca and Humacha members. This scheme recognizes the internal complexities of the formation, in that the Tilcara and Pico de Halcón members record sedimentation in areally-restricted incised valleys and contain structures indicative of tidal dominance, whereas the Casa Colorada, Alfarcito and Rupasca members typify wave-dominated open-marine environments, where background suspension-fallout was punctuated by oscillatory flows during storms. The Tilcara Member is incised into the underlying Mesón Group. The Casa Colorada Member reflects a basinwide Late Cambrian transgression and subsequent progradation and consists of lower to upper offshore deposits. The Pico de Halcón Member is incised into the Casa Colorada Member. The Alfarcito Member is divided into three distinctly upward-coarsening and-thickening intervals. The sandstone-dominated intervals are composed of lower to middle shoreface deposits with minor amounts of offshore transition and upper shoreface deposits. The heterolithic, fine-grained intervals record more distal deposition, ranging from the lower offshore to the offshore transition. The Rupasca Member is a dominantly fine-grained unit that records a major late early to early late Tremadocian transgression. The lower interval of this member consists of lower offshore to offshore-transition deposits, while the upper part is made up of shelf to lower offshore deposits. The Humacha Member is not exposed in the study area. The importance of integrating biostratigraphy within a sedimentologic and sequence-stratigraphic framework is underscored here, in that it enables us to construct a more accurate stratigraphic framework which permits a clear understanding of the sedimentary dynamics of this system.El análisis de las rocas del Cámbrico Superior-Tremadociano aflorantes en el área de Alfarcito, Cordillera Oriental, noroeste de Argentina, revela una serie de ciclos transgresivos-regresivos e incisiones de valles fluvio-estuarinos. Un estudio sedimentológico, bioestratigráfico y estratigráfico-secuencial integrado proporciona información para caracterizar las facies sedimentarias, analizar los patrones de apilamiento estratal y revisar el marco estratigráfico de estas sucesiones. La sucesión cámbrica-tremadociana es incluida en la Formación Santa Rosita, la cual es formalmente subdividida en seis miembros, Tilcara, Casa Colorada, Pico de Halcón, Alfarcito, Rupasca y Humacha. De este modo, este esquema retiene para el área de Alfarcito una unidad estratigráfica ampliamente aceptada como la Formación Santa Rosita y al mismo tiempo reconoce las complejidades internas de la misma, subdividiéndola en miembros. Los miembros Tilcara y Pico de Halcón registran depositación en valles incisos restringidos arealmente y contienen estructuras indicadoras de dominio mareal. Por el contrario, los miembros Casa Colorada, Alfarcito y Rupasca tipifican sedimentación en ambientes marinos abiertos dominados por el oleaje, donde la sedimentación por decantación alternó con flujos oscilatorios generados durante tormentas. El Miembro Tilcara está inciso en el subyacente Grupo Mesón. El Miembro Casa Colorada refleja una transgresión cámbrica tardía a escala de cuenca y la subsecuente progradación. En el área de estudio, esta unidad está representada por depósitos de offshore inferior a transición a offshore. El Miembro Pico de Halcón está inciso sobre el Miembro Casa Colorada. El Miembro Alfarcito está dividido en tres intervalos muy distintivos grano y estratocrecientes. Los intervalos arenosos están dominados por depósitos de shoreface inferior a medio con proporciones menores de depósitos de transición a offshore y shoreface superior. Los depósitos de los intervalos heterolíticos de grano fino registran depositación en un ambiente más distal, desde el offshore inferior a la transición al offshore. El Miembro Rupasca es una unidad dominantemente de grano fino, que registra una transgresión mayor de edad tremadociana temprana tardía a tardía temprana. El intervalo inferior del Miembro Rupasca consiste en depósitos de offshore inferior a transición a offshore, mientras que el intervalo superior consiste en depósitos de plataforma a offshore inferior. El Miembro Humacha no se encuentra expuesto en el área. La importancia de integrar estudios bioestratigráficos dentro de un marco sedimentológico y estratigráfico-secuencial es resaltada en este estudio. Este enfoque es esencial para construir un marco estratigráfico y correlaciones más precisas que ayuden a clarificar la nomenclatura estratigráfica de la cuenca.

Published
2006

7. Depositional environments and stratigraphy of the Upper Cambrian-lower Ordovician Santa Rosita formation at the Alfarcito area, Cordillera Oriental, Argentina: integration of biostratigraphic data within a sequence stratigraphic framework

Author

Luis A. Buatois, Fernando J. Zeballo, Guillermo L. Albanesi, Gladys Ortega, N. Emilio Vaccari, and M. Gabriela Mangano

Subjects
análisis de facies, estratigrafía secuencial, bioestratigrafía, marino somero, cámbrico-ordovícico, argentina, Geology, QE1-996.5, Geophysics. Cosmic physics, QC801-809
Abstract

The Upper Cambrian-Tremadocian rocks exposed in the Alfarcito area of Cordillera Oriental, northwest Argentina reveal a series of transgressive-regressive cycles punctuated by incision of fluvio-estuarine valleys. An integrated sedimentologic, biostratigraphic and sequence stratigraphic study permits characterization of the sedimentary facies and stratal stacking patterns, and a revision of the stratigraphic framework of this succession. The Upper Cambrian-Tremadocian succession is included within the existing Santa Rosita Formation, which is formally subdivided here into six units, the Tilcara, Casa Colorada, Pico de Halcón, Alfarcito, Rupasca and Humacha members. This scheme recognizes the internal complexities of the formation, in that the Tilcara and Pico de Halcón members record sedimentation in areally-restricted incised valleys and contain structures indicative of tidal dominance, whereas the Casa Colorada, Alfarcito and Rupasca members typify wave-dominated open-marine environments, where background suspension-fallout was punctuated by oscillatory flows during storms. The Tilcara Member is incised into the underlying Mesón Group. The Casa Colorada Member reflects a basinwide Late Cambrian transgression and subsequent progradation and consists of lower to upper offshore deposits. The Pico de Halcón Member is incised into the Casa Colorada Member. The Alfarcito Member is divided into three distinctly upward-coarsening and-thickening intervals. The sandstone-dominated intervals are composed of lower to middle shoreface deposits with minor amounts of offshore transition and upper shoreface deposits. The heterolithic, fine-grained intervals record more distal deposition, ranging from the lower offshore to the offshore transition. The Rupasca Member is a dominantly fine-grained unit that records a major late early to early late Tremadocian transgression. The lower interval of this member consists of lower offshore to offshore-transition deposits, while the upper part is made up of shelf to lower offshore deposits. The Humacha Member is not exposed in the study area. The importance of integrating biostratigraphy within a sedimentologic and sequence-stratigraphic framework is underscored here, in that it enables us to construct a more accurate stratigraphic framework which permits a clear understanding of the sedimentary dynamics of this system.

9. Tectonic controls on late Cambrian-Early Ordovician deposition in Cordillera oriental (Northwest Argentina)

Author

Romain Vaucher, Luis A. Buatois, Diego F. Muñoz, Beatriz G. Waisfeld, Diego Balseiro, Antoine Dillinger, and N. Emilio Vaccari

Subjects
010504 meteorology & atmospheric sciences, biology, Paleozoic, Biostratigraphy, 010502 geochemistry & geophysics, biology.organism_classification, 01 natural sciences, Trilobite, Tremadocian, Gondwana, Paleontology, Basement (geology), Ordovician, General Earth and Planetary Sciences, Sequence stratigraphy, Geology, 0105 earth and related environmental sciences
Abstract

The western Gondwana margin underwent a complex geodynamic history during the early Paleozoic, and major uncertainties remain as to the role of tectonism in sedimentary dynamics. This study focuses on the lower part Santa Rosita Formation and the coeval Guayoc Chico Group (Cordillera Oriental; Northwest Argentina), ranging from the late Cambrian (Furongian; Age 10) to Early Ordovician (early Tremadocian; Tr1). This stratigraphic interval has been previously interpreted as deposited in an extensional basin to a retro-arc basin without major regional tectonic-induced deformation during its deposition, only recording long-term relative sea-level fluctuations. Four areas (Sierra de Cajas, Angosto del Moreno, Quebrada de Trancas, and Quebrada de Moya) were chosen because they host the most complete and temporally well-constrained stratigraphic sections of the Cordillera Oriental. Throughout the stratigraphic sections, four main facies zones are described and attributed to deposition in estuarine, foreshore-shoreface, delta-front, and offshore environments. Trilobite biozones are used as the biostratigraphic framework. By integrating sedimentary facies analysis, biostratigraphy, and sequence stratigraphy from the four selected sections, a new scenario showcasing the evolution of the basin is proposed. This scenario interprets a tectonically induced deformation during the deposition of the Santa Rosita Formation and the coeval Guayoc Chico Group. The newly acquired sedimentological data show that physiographical changes took place during the Cambrian-Ordovician transition and are expressed in various localities. This major change is recorded in the stratigraphic architecture, where extensive wave-ravinement surfaces and sedimentary hiatus are the result of local, syn-depositional basement uplifts. The initiation of the Puna-Famatinian volcanic arc during the Early Ordovician on the western margin was likely responsible for deformation in the retro-arc basin and the proposed scenario is consistent with the stratigraphic evolution in other areas of the Cordillera Oriental (e.g., Sierra de Mojotoro) and the Sierra de Famatina. Therefore, this study helps to constrain the evolution of the western Gondwana margin during the early Paleozoic, showing changes in the stratigraphic architecture and basin evolution from an extensional to a retro-arc style.

Published
2020
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10. Reassessment of the Order Trinucleida (Trilobita)

Author

Arnaud Bignon, Beatriz G. Waisfeld, N. Emilio Vaccari, and Brian D. E. Chatterton

Subjects
0106 biological sciences, Systematics, 010506 paleontology, Paleontology, SUPERFAMILY, Primary care, Anatomy, Biology, biology.organism_classification, 010603 evolutionary biology, 01 natural sciences, Cladistics, Suture (anatomy), Order (business), Asaphida, 0105 earth and related environmental sciences
Abstract

Trinucleoids have been considered as a superfamily of the Order Asaphida, based on: a pre-occipital glabellar tubercle, a cephalic median suture in most ancestral forms, and the presence of broadly...

Published
2020
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11. The homalonotid trilobiteBurmeisteriaSalter, 1865 in the Lower Devonian of Argentina: new data in the context of southwestern Gondwana

Author

Juan José Rustán, Beatriz G. Waisfeld, and N. Emilio Vaccari

Subjects
Paleontology, Gondwana, Taphonomy, biology, Genus, Context (language use), Structural basin, biology.organism_classification, Geology, Devonian, Burmeisteria, Trilobite
Abstract

The homalonotid trilobiteBurmeisteriaSalter, 1865 is revised from material from the Lower Devonian of central western Argentina (the Talacasto Formation in the Precordillera Basin). In contrast to other closely related Devonian marine basins from South America (mainly Bolivia, Brazil and Uruguay), the only species recognized in Argentina includeBurmeisteria herschelii(Murchison, 1839) andB.notica(Clarke, 1913). New observations on the structure of the carapace indicate that structures sometimes interpreted as granules with taxonomic meaning are, in fact, taphonomic characters that represent the fillings of pore canals exposed by decortication. The antero-ventral process of the rostral plate may be a locking device during enrollment, which allowed long-term defensive behavior with a minimum of muscular energy.Burmeisteriais an upper Silurian to Middle Devonian endemic representative of southwestern Gondwanan (Malvinokaffric) basins. In the Argentine Precordillera Basin, this genus is virtually restricted to a sandy, Pragian, stratigraphic interval capped by a marker bed first reported by Keidel in 1921.

Published
2020
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12. Were all trilobites fully marine? Trilobite expansion into brackish water during the early Palaeozoic

Author

Beatriz G. Waisfeld, Ricardo A. Astini, N. Emilio Vaccari, Luis A. Buatois, M. Gabriela Mángano, and Diego F. Muñoz

Subjects
010506 paleontology, Paleozoic, Trace fossil, 010502 geochemistry & geophysics, 01 natural sciences, General Biochemistry, Genetics and Molecular Biology, Paleontology, Animals, 14. Life underwater, Ordovician radiation, Arthropods, Saline Waters, 0105 earth and related environmental sciences, General Environmental Science, geography, geography.geographical_feature_category, General Immunology and Microbiology, Brackish water, biology, Fossils, Estuary, General Medicine, Euryhaline, biology.organism_classification, Tremadocian, Trilobite, Palaeobiology, Estuaries, General Agricultural and Biological Sciences, Geology
Abstract

Trilobites, key components of early Palaeozoic communities, are considered to have been invariably fully marine. Through the integration of ichnological, palaeobiological, and sedimentological datasets within a sequence-stratigraphical framework, we challenge this assumption. Here, we report uncontroversial trace and body fossil evidence of their presence in brackish-water settings. Our approach allows tracking of some trilobite groups foraying into tide-dominated estuaries. These trilobites were tolerant to salinity stress and able to make use of the ecological advantages offered by marginal-marine environments migrating up-estuary, following salt wedges either reflecting amphidromy or as euryhaline marine wanderers. Our data indicate two attempts of landward exploration via brackish water: phase 1 in which the outer portion of estuaries were colonized by olenids (Furongian–early late Tremadocian) and phase 2 involving exploration of the inner to middle estuarine zones by asaphids (Dapingian–Darriwilian). This study indicates that tolerance to salinity stress arose independently among different trilobite groups.

Published
2021
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13. The Upper Ordovician trinucleid trilobiteBancroftolithusfrom the Precordillera of Argentina

Author

Brian D. E. Chatterton, Gregory D. Edgecombe, Beatriz G. Waisfeld, and N. Emilio Vaccari

Subjects
biology, Paleontology, TRILOBITE, biology.organism_classification, ORDOVICIAN, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Trilobite, Katian, Taxon, Genus, Group (stratigraphy), Ordovician, Period (geology), Type locality, PRECORDILLERA, Meteorología y Ciencias Atmosféricas, CIENCIAS NATURALES Y EXACTAS, Geology, TRINUCLEIDAE
Abstract

The trinucleid trilobite Bancroftolithus Baldis and Pthe, 1995 includes a group of species from Sandbian strata of the Argentine Precordillera. The monotypic Hunickenolithus Baldis and Pthe, 1995 from the Las Aguaditas Formation at its type locality in San Juan Province is placed in the synonymy of Bancroftolithus. Of four nominal taxa from the Las Aguaditas Formation, B. pozensis Baldis and Pthe, 1995, and B. hughesi Baldis and Pthe, 1995 are retained, and both are revised based on new collections from the type locality that include ontogenetic series from the protaspid period. Two protaspid stages are recognized in both species. Three additional species (Bancroftolithus alki n. sp., B. cf. B. pozoensis, Bancroftolithus sp.) from broadly coeval strata in the Las Plantas Member of the Las Vacas Formation in La Rioja Province are identified as the closest relatives of the Las Aguaditas species. Bancroftolithus alki also occurs in the Los Azules Formation in San Juan Province. The five species included in this regional clade exhibit significant morphological differences in the lower lamellae, an unusual feature among the Trinucleidae. Bancroftolithus is evidently most closely related to the Australian Katian genus Parkesolithus. The two are not convincingly assigned to any of the existing trinucleid subfamilies. Fil: Waisfeld, Beatriz Graciela. 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; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones Paleobiológicas; Argentina Fil: Vaccari, Norberto Emilio. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones Paleobiológicas; Argentina. 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; Argentina Fil: Edgecombe, Gregory D.. Natural History Museum; Reino Unido Fil: Chatterton, Brian D. E.. University of Alberta; Canadá

Published
2011
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14. PALEOECOLOGICAL DYNAMICS OF FURONGIAN (LATE CAMBRIAN) TRILOBITE-DOMINATED COMMUNITIES FROM NORTHWESTERN ARGENTINA

Author

Diego Balseiro, Beatriz G. Waisfeld, and N. Emilio Vaccari

Subjects
EVOLUTIONARY FAUNA, biology, Fauna, DIVERSITY, Paleontology, biology.organism_classification, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Trilobite, EVENNESS, Critical moment, Intermediate Disturbance Hypothesis, Time averaging, Species evenness, Submarine pipeline, Transgressive, DISTURBANCE, Meteorología y Ciencias Atmosféricas, CIENCIAS NATURALES Y EXACTAS, Ecology, Evolution, Behavior and Systematics, Geology
Abstract

The Cambrian–Ordovician boundary interval is a critical moment in the ecology of trilobite communities. To understand this transition, we studied—at three different spatial scales—changes in the structure of olenid-dominated communities included in the Parabolina fauna, which flourished in the latest Cambrian, largely storm-dominated, successions of northwestern Argentina. At the local (,meter) scale, species-poor communities occur in shoreface deposits. Relatively flat species-abundance distributions (SADs) and high evenness characterize upper offshore to offshore transition settings of the early highstand systems tract (HST), whereas uneven SADs in species-poor communities are typical of the lower offshore and shelf environments of the transgressive systems tract (TST). This pattern is unlikely to be caused by a change in time averaging and is consistent with the intermediate disturbance hypothesis predicting unimodal diversity gradients. The pattern is thus interpreted to be related to a trend in intensity and frequency of storm disturbance along local shallowing-upward gradients. At the regional scale (,100 km), the diversity trend across the sampled west-east transect is rather variable and does not match the depth or oxygen-related gradients. At the biogeographic scale, the patterns of abundance of two key taxa (Parabolina and Asaphellus) show contrasting abundance and occupancy patterns between the Cordillera Oriental siliciclastic settings and the more carbonate-rich settings of Famatina (Argentina) and Oaxaca (Mexico). The presence of these genera in settings spatially adjacent, but environmentally different from their preferred habitats can represent a signature of source-sink dynamics. Low sample evenness values for the Cordillera Oriental contrast with those of coeval Laurentian communities, implying that a secular increase in evenness took place earlier in Laurentia than in Gondwana. Fil: Balseiro, Diego. 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; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones Paleobiológicas; Argentina Fil: Waisfeld, Beatriz Graciela. 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; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones Paleobiológicas; Argentina Fil: Vaccari, Norberto Emilio. 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; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones Paleobiológicas; Argentina

Published
2011
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15. Infaunal molting in Trilobita and escalatory responses against predation

Author

Diego Balseiro, Rodolfo D. Foglia, Beatriz G. Waisfeld, N. Emilio Vaccari, and Juan José Rustán

Subjects
ARGENTINA, biology, Paleozoic, Ecology, INFAUNALISM, Lineage (evolution), SILURO-DEVONIAN, Geology, Context (language use), biology.organism_classification, TRILOBITA, Devonian, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Trilobite, Predation, Paciphacops, Adaptation, Meteorología y Ciencias Atmosféricas, CIENCIAS NATURALES Y EXACTAS
Abstract

The outstanding fossil record of trilobites contrasts with our limited knowledge of their lifestyles and strategies. Aspects such as infaunalism and behavioral defensive skills in this group have yet to be demonstrated conclusively. We report new insights based on a striking sclerite configuration exhibited by three phacopid trilobite species, part of a late Silurian-Early Devonian Paciphacops (Paciphacops) Maksimova, 1972, lineage. An unusual molt pattern provides compelling evidence of infaunal behavior, which accounts for a hiding, antipredatory adaptation. In addition, strengthening of the exoskeleton and acquisition of spines indicate an evolutionary trend toward morphological defensive strategies. Both trends in active and passive traits are considered escalatory in nature, thus providing unequivocal support for understanding the ecological role of trilobites as a main prey group in the context of the global diversification of predators recorded during middle Paleozoic time. Fil: Rustán, Juan José. 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; Argentina Fil: Balseiro, Diego. 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; Argentina Fil: Waisfeld, Beatriz Graciela. 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; Argentina Fil: Foglia, Rodolfo Diego. 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; Argentina Fil: Vaccari, Norberto Emilio. 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; Argentina

Published
2011
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16. Delamaran Trilobites from the La Laja Formation, San Juan, Argentina

Author

Rodolfo D. Foglia and N. Emilio Vaccari

Subjects
Paleontology, Taxon, biology, Fauna, Laurentia, Hiatus, biology.organism_classification, Ecology, Evolution, Behavior and Systematics, Geology, Trilobite
Abstract

The La Laja Formation lies exposed almost continuously along the western margin of two hill ranges, i.e., the Sierra Chica de Zonda and Sierra de Villicum. This limestone unit bears a remarkable fauna of Cambrian trilobites. In this work we analyse the Delamaran trilobite fauna from the upper part of the El Estero Member and the lower third of the Soldano Member of the La Laja Formation. Taxa described are Glossopleura walcotti Poulsen, Glossopleura lodensis (Clark), Fieldaspis sp., and Prozacanthoides zondaensis n. sp. The Poliella denticulata, Mexicella mexicana?, and Glossopleura walcotti Zones are documented; these had been previously included in a hiatus. Trilobites-based correlations are established between the La Laja Formation and olistoliths of the Western Precordillera. Additional correlations are also suggested between the Precordillera and different localities in Laurentia. Finally, we discuss the biogeographic implications of the described material. Delamaran taxa reported from the La Laja Formation are characteristic and so far restricted to Laurentia. Analysis of the trilobite fauna from this unit supports the allochtonous origin of the Precordillera.

Published
2010
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17. The aulacopleurid trilobiteMaurotarionAlberti, 1969, in the Silurian-Devonian of Argentina: systematic, phylogenetic and paleobiogeographic significance

Author

Juan José Rustán and N. Emilio Vaccari

Subjects
Synapomorphy, Paleontology, Phylogenetic tree, Biology, Subgenus, Clade, biology.organism_classification, Devonian, Sea level, Lochkovian, Trilobite
Abstract

Five new species ofMaurotarionAlberti, 1969 from the Silurian Lipeón Formation and Lower Devonian Talacasto Formation of Argentina are recognized. The comparisons with Bolivian and South African species support a Malvinokaffric clade based on librigenal synapomorphies, here erected asMaurotarion(Malvinotarion) new subgenus. The Malvinokaffric origin of the family would not be a migration from lower paleolatitudes but an Early Silurian stock of rare cosmopolitan ancestors which underwent a great Devonian radiation. Two lineages can be recognized within MalvinokaffricMaurotarion.The Silurian-Pragiandereimsilineage is a plesiomorphic one resembling Silurian representatives and involvesM.(Malvinotarion)dereimsi, M.(Malvinotarion)talacastoensenew species,M.(Malvinotarion?) new species A,M.(Malvinotarion?) new species B,M.(Malvinotarion) sp., and eventuallyM. (Malvinotarion?)cf.dereimsi.Theisaacsonilineage ranges from the Lower Pragian to Eifelian exhibiting a defined morphologic trend in the librigena. This lineage comprisesM.(Malvinotarion)isaacsoni, M.(Malvinotarion) sp. A from South Africa,M.(Malvinotarion)gauchonew species,M.(Malvinotarion)haudeinew species andM.(Malvinotarion)legrandi.A Lochkovian diversification probably took place yet an adequate assessment remains difficult. In contrast, a great evolutionary burst is recognized during the Emsian and is related to Pragian-Emsian global relative sea level curves which are coincident with those proposed from Bolivian and Argentinian basins.

Published
2010
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18. KainellaWalcott, 1925 (Trilobita, Ordovícico Temprano) en el noroeste de Argentina y sur de Bolivia. Paleontología sistemática

Author

Beatriz G. Waisfeld and N. Emilio Vaccari

Subjects
Cuesta, Geography, geography.geographical_feature_category, Taxon, Ordovician, Paleontology, Taxonomy (biology), Type locality, Archaeology, Ecology, Evolution, Behavior and Systematics, Tremadocian
Abstract

Kainella Walcott, 1925 (Trilobita, Early Ordovician) in Northwestern Argentina and Southern Bolivia. Systematic Paleontology. A taxonomic study is presented involving different species of Kainella from the Central Andean Basin. These early Tremadocian species come from the Santa Rosita, Cardonal, and Devendeus formations, and also from the Guayoc Chico Group; all units lie exposed at numerous localities in the Argentine Cordillera Oriental. Also analyzed are Kainella species from the Iscayachi Formation exposed in the Yunchara Segment in southern Bolivia. A group of eight species is recognized, suggesting a significantly greater diversity than previously assessed. An emmended diagnosis of K. meridionalis Kobayashi is provided, and a lectotype is designated. On this basis, some of the former assignments to this species are now rearranged into the taxa described herein. Complete morphological information is provided on K. andina Suarez Soruco, based on new collections from its type locality (Cuesta...

Published
2010
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19. KainellaWalcott, 1925 (Trilobita, Ordovícico Temprano) en el noroeste de Argentina y sur de Bolivia. Importancia bioestratigráfica

Author

Beatriz G. Waisfeld, LeGrand Smith, Larisa F. Marengo, and N. Emilio Vaccari

Subjects
Paleontology, Geography, Range (biology), Genus, Ordovician, Biozone, Ecological succession, Biostratigraphy, Structural basin, Ecology, Evolution, Behavior and Systematics, Tremadocian
Abstract

Kainella Walcott (trilobita, Early Ordovician) In Northwestern Argentina And Southern bolivia. Biostratigraphic Significance. The Tremadocian Kainella meridionalis Zone in the Central Andean Basin is is reassessed. This zone has been widely used for regional and intercontinental correlations, but such correlations mostly involved an extended interval that corresponds, in fact, to the whole range of the genus. Species of Kainella recorded in northwestern Argentina and southern Bolivia exhibit a relatively wide geographic distribution and a constrained stratigraphic range. On the basis of their record a succession of biozones is proposed, ranging from the basal Tremadocian to possibly the early middle Tremadocian. Three biozones are proposed on the basis of integrated information drawn from several localities, i.e., the K. andina, K. meridionalis, and K. teiichii zones. In addition, the Jujuyaspis keideli Subzone is here upgraded to the rank of zone. The definition of this succession of biozones i...

Published
2010
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20. High Resolution Trilobite Biostratigraphy for the Early Late Tremadocian (Tr2) Interval (Early Ordovician) Santa Rosita Formation, Argentine Cordillera Oriental

Author

Beatriz G. Waisfeld, Diego F. Muñoz, Facundo René Meroi Arcerito, and N. Emilio Vaccari

Subjects
010506 paleontology, LOWER ORDOVICIAN, Fauna, Biozone, Biostratigraphy, 010502 geochemistry & geophysics, 01 natural sciences, Paleontología, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Paleontology, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, biology, biology.organism_classification, CENTRAL ANDEAN BASIN, Trilobite, Tremadocian, Gondwana, Taxon, TRILOBITES, Ordovician, CORRELATION, BIOZONATION, CIENCIAS NATURALES Y EXACTAS, Geology
Abstract

The early late Tremadocian (Tr2) interval is exceptionally well-represented in eastern areas of the Argentine Cordillera Oriental. New field collections and detailed taxonomic reassessments, as well as a reevaluation of regional data, permit the development of a highly resolved trilobite-based biostratigraphic framework. The concept of the traditional Bienvillia tetragonalis biozone is emended and the new Asaphellus nazarenensis biozone is proposed. Hence, the Tr2 interval encompasses a succession of four trilobite biozones including in ascending order the Kainella teiichii, the Bienvillia tetragonalis, the Asaphellus nazarenensis, and the Notopeltis orthometopa biozones. This resolution is notably higher than that provided by biostratigraphically significant groups such as graptolites and conodonts, and allows a detailed basinwide correlation. New taxonomic information on A. nazarenensis Tortello and Esteban and N. orthometopa (Harrington), is provided and the new species Asaphellus albae sp. nov. is defined. Detailed correlation of the trilobite fauna from the Tr2 interval with that of other paleocontinents is difficult. Taxa are mostly endemic or display wide geographic distributions but with long stratigraphic ranges. Overall, both trilobite-based and indirect international correlations highlight that this interval is hardly recognized, incompletely preserved, or the trilobite fauna is poorly known in most areas of Gondwana. Consequently, due to the completeness of the stratigraphic and fossil records of the Tr2 in the Cordillera Oriental, this region represents a global reference site for the study of this interval. El intervalo Tremadociano temprano tardío (Tr2) está excepcionalmente representado en la Cordillera Oriental, en sus flancos oriental y central. Nuevas colecciones, una revisión taxonómica moderna y la reevaluación de datos regionales, permitieron desarrollar un esquema bioestratigráfico de alta resolución con trilobites. Se modifica el concepto de la clásica biozona de Bienvillia tetragonalis y se establece una nueva unidad, la biozona de Asaphellus nazarenensis. Por lo tanto, el intervalo Tr2 presenta una sucesión de cuatro biozonas de trilobites, en orden ascendente: Kainella teiichii, Bienvillia tetragonalis, Asaphellus nazarenensis y Notopeltis orthometopa. El grado de resolución de este esquema duplica aquél de otros grupos de importancia bioestratigráfica como graptolitos y conodontes, permitiendo de esta manera mayores precisiones en la correlación regional. Asimismo, se brinda nueva información sobre las especies A. nazarenensis Tortello y Esteban y N. orthometopa (Harrington), y se define una nueva especie de asáfido: Asaphellus albae sp. nov. La posibilidad de correlación con sucesiones de otros paleocontinentes para el Tr2 es limitada ya que la mayoría de los taxa son endémicos, o bien presentan una distribución geográfica amplia pero frecuentmente, extensos rangos. Finalmente, tanto las correlaciones basadas en trilobites como aquéllas indirectas sugieren que el intervalo Tr2 es difícil de reconocer, su registro es fragmentario y/ o la fauna de trilobites es pobremente conocida en gran parte de Gondwana. Por lo tanto, dado el completo registro estratigráfico y paleontológico del Tr2 en la Cordillera Oriental, ésta constituye un sitio de referencia a nivel mundial para el estudio de este intervalo. Fil: Meroi Arcerito, Facundo René. Instituto de Investigaciones en Biodiversidad y Biotecnología , Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Mar del Plata (Grupo de entomología edáfica bonaerense subooriental), Mar del Plata; Argentina Fil: Waisfeld, Beatriz Graciela. 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; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones Paleobiológicas; Argentina Fil: Vaccari, Norberto Emilio. 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; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones Paleobiológicas; Argentina Fil: Muñoz, Diego Fernando. 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; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones Paleobiológicas; Argentina

Published
2018
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21. First record of Lower Silurian conodonts from South America: biostratigraphic and palaeobiogeographic implications of Llandovery conodonts in the Precordillera of Argentina

Author

N. Emilio Vaccari, Stig M. Bergström, Oliver Lehnert, and Juan L. Benedetto

Subjects
Paleontology, Geology
Abstract

A collection of conodonts, including Dapsilodus obliquicostatus (Branson & Mehl), Distomodus cf. kentuckyensis Branson & Branson, Ozarkodina oldhamensis (Rexroad), and Panderodus sp., has been obtained from brachiopod coquinas in the lower part of the La Chilca Formation in the Precordillera of west-central Argentina. This conodont fauna, the first to be recorded from the Llandovery in South America, can be referred to the D. kentuckyensis Biozone, and is interpreted to represent an interval in the middle Rhuddanian to lower Aeronian stages. This age assignment is supported by graptolite data from the lower third of the La Chilca Formation beneath the conodont-bearing interval. The brachiopods associated with the conodonts belong to the Afro-South American Realm, but include a high percentage of North Atlantic and cosmopolitan genera. The conodont taxa present are widespread in the tropical zone (Laurentia, Baltica, etc.). This suggests that the pronounced conodont faunal provicialism in the Upper Ordovician had disappeared in the Lower Silurian, where high- and low-latitude conodont faunas appear to be closely similar.

Published
1999
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22. New insights into the early diversification of the ostracoda: Tremadocian ostracods from the cordillera oriental, Argentina

Author

María José Salas and N. Emilio Vaccari

Subjects
biology, Ecology, Fauna, Ostracoda, Argentina, Paleontology, Andes, Structural basin, Diversification (marketing strategy), Early Diversification, biology.organism_classification, Tremadocian, Ciencias de la Tierra y relacionadas con el Medio Ambiente, purl.org/becyt/ford/1 [https], purl.org/becyt/ford/1.5 [https], Gondwana, Genus, Group (stratigraphy), Ostracod, Meteorología y Ciencias Atmosféricas, CIENCIAS NATURALES Y EXACTAS
Abstract

New species of ostracods from the Tremadocian in the northwest region of Argentina are described. These are among the earliest well-documented records of ostracods, which shed new light onto the early diversification of the group. The described fauna consists of seven species, five of which are new: Saltite uchuy sp. nov., Saltite kuraq sp. nov., Conchoprimitia? iglesiasi sp. nov., Orechina violetae sp. nov., and Orechina catalinae sp. nov. The fauna consists primarily of soanellids, a non-dimorphic family of palaeocopids, and of binodicopids. One factor leading to diversification of the group in this region may have been the complex configuration of the northwest basin, which had a restricted pattern of circulation. The distribution of the first ostracods is largely restricted to Gondwana and peri-Gondwana regions. Accordingly, it is possible to envision that the origin or at least an important radiation of the group was centred in this region. Both the Soanellidae and the genus Orechina would have originated in Gondwana and would have become widespread later during the Middle Ordovician. The Tremadocian fauna located in Argentina show significant affinities with fauna located in the warm-water setting of the east Gondwana, mainly in Australia and China. Fil: Salas, Maria Jose. 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; Argentina Fil: Vaccari, Norberto Emilio. 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; Argentina

Published
2012

24. Early Devonian trilobites from the Sierra de Las Minitas, northernmost Precordillera (La Rioja province), Argentina

Author

Juan José Rustán, Ricardo A. Astini, and N. Emilio Vaccari

Subjects
ARGENTINA, Taphonomy, biology, PROCORDILLERA, Lithology, Fauna, DEVONIAN, Paleontology, Ecological succession, biology.organism_classification, Devonian, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Trilobite, purl.org/becyt/ford/1 [https], Taxonomic composition, purl.org/becyt/ford/1.5 [https], TRILOBITES, Paciphacops, Meteorología y Ciencias Atmosféricas, CIENCIAS NATURALES Y EXACTAS, Ecology, Evolution, Behavior and Systematics, Geology
Abstract

Early Devonian trilobites are described based on material from Sierra de Las Minitas, in the northern extent of the Precordillera, western Argentina. This diverse fauna, the first one known from La Rioja Province, includes a species of the phacopid Paciphacops (Paciphacops) Maksimova, the calmoniids Talacastops zarelae Edgecombe, Vaccari and Waisfeld and Tormesiscus Waisfeld, Edgecombe and Vaccari, together with a proetid (Unguliproetus? sp.) and a dalmanitid. Fossils are preserved in nodules within a strongly folded dark and bioturbated shaley succession, included in a structural and stratigraphically complex geological setting. The taxonomic composition and taphonomic signature of the studied fossil locality are closely similar to those recognized within the lower part of the Talacasto Formation at Las Aguaditas section in San Juan Province. Lithologic and faunistic similarities allow a reliable stratigraphic correlation between both localities; therefore, the trilobite bearing rocks from the Sierra de Las Minitas are interpreted as the northernmost outcrops of the Talacasto Formation in the Argentine Precordillera and are considered to be Lochkovian in age. The remarkable lateral continuity of this fossiliferous stratigraphic interval indicates, as previously suggested, the development of a wide muddy-shelf setting in the Early Devonian Precordillera Basin. Fil: Rustán, Juan José. 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; Argentina Fil: Vaccari, Norberto Emilio. 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; Argentina Fil: Astini, Ricardo Alfredo. 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; Argentina

Published
2011
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25. The oldest record of Eothinoceratidae (Ellesmerocerida, Nautiloidea): Middle Tremadocian of the Cordillera Oriental, NW Argentina

Author

N. Emilio Vaccari and Marcela Cichowolski

Subjects
Siphuncle, biology, Range (biology), Carbonate platform, Geology, biology.organism_classification, Tremadocian, ORDOVICIAN, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Paleontology, Genus, Floian, Ordovician, Geología, TREMADOCIAN, NAUTILOID CEPHALOPODS, Ellesmerocerida, EOTHINOCERATIDAE, NW ARGENTINA, CIENCIAS NATURALES Y EXACTAS
Abstract

Middle Tremadocian cephalopods from the Sierra de Mojotoro, Cordillera Oriental, NW Argentina, are assigned to Saloceras cf. sericeum (Salter) based on the siphuncle morphology and general shape of the conch. Saloceras sericeum (Salter) is known from the Upper Tremadocian and Floian of England and Wales, a region that formed part of eastern Avalonia during the Early Ordovician, located at a high southern latitude to the north of the Gondwanan margin. This is the oldest record of this genus and of the family Eothinoceratidae, and extends the geographical range of Saloceras, being the first positive record of its presence in Argentina and the Central Andean Basin. These remains are amongst the oldest cephalopods described from NW Argentina. They represent the third mid Tremadocian record of nautiloids at relatively high palaeolatitudes and away from the low latitude carbonate platform palaeoenvironments where the bulk of the earliest cephalopods resided. Fil: Cichowolski, Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Vaccari, Norberto Emilio. 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; Argentina

Published
2011
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