COMMENTS ON SOME SYRINGOTHYRIDOIDEA (BRACHIOPODA) FROM THE CARBONIFEROUS OF NORTH AFRICA

The type species of the spiriferinide genus Histosyrinx Termier & Termier (Brachiopoda), namely Histosyrinx vautrini Termier & Termier, is re-investigated in detail on the basis of its type material from the Tournaisian Marar Formation (Serdeles area, Murzuq Basin, Libya), including additional specimens from the same region, and from the Tournaisian of Algeria (Reggane Basin). The internal morphology of the ventral valve of Histosyrinx vautrini is particularly variable, notably concerning the development of the septal pillow, the subdelthyrial plate and the median septum. Histosyrinx can be easily distinguished from the genus Septosyringothyris Vandercammen by the absence of a true delthyrial plate and the lesser development of the median septum. Histosyrinx is also close to Syringopleura Schuchert, which is generally considered as a synonym of Syringothyris Winchell, by its ventral internal features (e.g. development of a septal pillow), but the dorsal internal morphology of the type species of Schuchert’s genus remains unknown. Thus, the relationships between both genera need to be investigated further. Specimens from the southern margin of the Tindouf Basin (Algeria), previously identified as Septosyringothyridinae? gen. indet. by Legrand-Blain in the 1970s, are fully illustrated here for the first time and referred to an unidentified genus of the subfamily Permasyrinxinae on the basis of the absence of syrinx. &nbsp

Enhancement of paleozoic geosites of the Jagüé Bolson for its integration in the touristic product of laguna Brava, La Rioja province, Argentina

El Bolsón de Jagüé en el noroeste de la provincia de La Rioja (departamento Vinchina), guarda un importante registro geológico de la Era Paleozoica, particularmente de los períodos Devónico, Carbonífero y Pérmico (419-252 Ma). Este intervalo estuvo caracterizado por fuertes contrastes climáticos que variaron desde condiciones frías de tundra, pasando por climas templados húmedos hasta desérticos, en un paisaje marcadamente cambiante con frecuentes ingresiones marinas, afectado por el tectonismo y volcanismo que caracterizaron este margen de Gondwana. El objetivo del presente trabajo es la puesta en valor de sitios geológico/paleontológicos (geositios) del Bolsón de Jagüé, con el fin de integrarlos a un producto turístico existente: Laguna Brava. Se aplicaron criterios científicos y turísticos, utilizando una metodología que contempló relevamiento de fuentes secundarias, análisis del marco legal y aplicación de fichas elaboradas para este caso. De los geositios analizados sólo un número reducido, además de su importancia científica, reúne una serie de aspectos (accesibilidad, cercanía al circuito turístico existente, valor paisajístico, conservación, entre otros), que permitirían su integración al producto turístico Laguna Brava. Conclusiones preliminares indican que el registro fosilífero y la diversidad geológica convierten al Bolsón de Jagüé en un área con potencial para el turismo educativo y científico.The Bolsón de Jagüé in the northwest of the province of La Rioja (district of Vinchina), keeps an important geological record of the Paleozoic Era, particularly of the Devonian, Carboniferous, and Permian periods (419-252 Ma). This interval was characterized by strong climatic contrasts ranging from cold tundra to desert climates, going through humid and moderate climates, in a markedly changing landscape with frequent marine ingressions, affected by the tectonism and volcanism that characterized this Gondwana margin. The purpose of this work is the enhancement of geological and paleontological sites (geosites) of the Bolsón de Jagüé, in order to integrate them into an existing tourism product: Laguna Brava. Scientific and touristic criteria were applied, using a methodology that included a survey of secondary sources, analysis of the legal framework, and application of files prepared for this case. In addition to its scientific importance, only a small number of the geosites analyzed, brings together a number of aspects (accessibility, proximity to the existing tourist circuit, landscape value, conservation, among others), which would allow its integration into the Laguna Brava tourism product. Preliminary conclusions indicate that fossil record and geological diversity make the Bolsón de Jagüé an area with potential for educational and scientific tourism.Fil: Salvadeo, Victoria. Universidad Nacional de La RiojaFil: Cisterna, Gabriela A.. Universidad Nacional de La RiojaFil: Vaccari, Emilio. Universidad Nacional de La Rioj

BRACHIOPOD ASSEMBLAGES OF THE EURYDESMA FAUNA IN GLACIAL- DEGLACIAL SEQUENCES FROM ARGENTINA AND AUSTRALIA

The Eurydesma Fauna characterizes the Late Pennsylvanian-Permian glacial-postglacial sediments recorded in several Gondwanan basins during the Late Paleozoic Ice Age (LPIA). Brachiopods, as one the most significant components of this fauna, are herein analyzed along with the associated bivalves, in two key sections from western and eastern Gondwana (Bonete Formation in the Sauce Grande Basin, eastern Argentina, and the Wasp Head Formation in the southern Sydney Basin, eastern Australia). The preliminary quantitative analysis indicates a high compositional similarity in both regions but occupancy exhibits important differences: brachiopod-dominated faunas can be found in eastern Australia (Tomiopsis and Trigonotreta are the most frequent taxa), and bivalve-dominated faunas are characteristic in eastern Argentina, where the brachiopods are poorly represented with the genera Tivertonia and Tomiopsis. In this locality, the development of r-strategy taxa, such as the bivalve Eurydesma, during the end of a glacial episode would adversely affect brachiopods’ abundance. This is also consistent with previous studies that indicate that brachiopods already showed a decrease in importance in Pennsylvanian communities from Argentina. Relative abundances of brachiopods and bivalves in both localities may reflect differences in the regional environmental conditions but, unfortunately, eastern Argentina lacks younger records to compare the faunal turnover with that of the Australian sequences. Despite the ecological structural differences identified (i.e. brachiopod:bivalve ratio), the postglacial Eurydesma fauna flourished in western and eastern Gondwana and it is striking that two faunas located on the opposite margins of this paleocontinent show such high compositional similarity during the development of a global postglacial event. This is particularly significant considering that the type of the basins (i.e. restricted vs open basins), biological features, paleoenvironmental conditions directly related to glacial dynamics, and also the diachronism of the transgression, can be controlling the composition of this fauna

Permian brachiopods from the Tupe formation, San Juan Province, Precordillera, Argentina

The brachiopod fauna from the Tupe Formation at La Herradura Creek, located on the west flank of Perico Hill, San Juan Province, Argentina, palaeogeographically belongs to the western sector of the Paganzo basin (\u27Guandacol embayment\u27). The stratigraphical section of the Tupe Formation at La Herradura Creek is the stratotype of the Tivertonia jachalensis-Streptorhynchus inaequiornatus biozone, was previously regarded as being of Late Carboniferous age but here is assigned to the earliest Permian (Asselian). We describe and review the biozone assemblage, which consists of Streptorhynchus inaequiornatus, Tivertonia jachalensis, Kochiproductus sp., Costatumulus sp., Coronalosia argentinensis, Tupelosia paganzoensis, Trigonotreta pericoensis, Septosyringothyris sp. aff. Septosyringothyris jaguelensis and Crurithyris? sp. This brachiopod assemblage is related to Indian and Australian Early Permian faunas and its presence in the La Herradura Creek section provides new evidence in support of an Asselian (Early Permian) age for the Tivertonia jachalensis-Streptorhynchus inaequiornatus biozone. This assemblage is also important for intra- and inter-basinal correlation because several of its characteristic species have been identified from other sections of the Paganzo basin and the Riacuteo Blanco basin. The proposed age for this biozone is consistent with the age of palynological data from slightly above the marine faunas from the stratotype locality. <br /

The Permian brachiopod genus Trigonotreta Koenig and its occurrence in Argentina

A review of the Permian spiriferid brachiopod genus Trigonolrela and its occurrence in the Early Permian of Argentina is provided herein. Several species are known from the Late Palaeozoic sequences of the Argentinean Precordillera. These include Trigonolrela sp. and Trigonolrela riojanensis (Lech and Acenolaza), from the Rio del Peii.on Formation (Rio Blanco Basin), Trigonolrela pericoensis (Leanza), from the Tupe Formation at the La Herradura creek locality (Paganzo Basin) and Trigonolrela sanjuanensis (Lech and Acenolaza), from Del Salto Formation (Calingasta-Uspallata Basin). These species are characterised by being small to medium sized, relatively transverse, with cardinal extremities often strongly angular. Costae are weakly bifurcated and superimposed on weakly developed lateral flank plications adjacent to the fastigium and sulcus. The Argentinean species are close to the oldest known Indian species of the genus, Trigonotreta hesdoensis (Salmi and Dutt), particularly with respect to the nature of its weakly fasciculated costae. Further study will refine the details of the relationship of the South American species with those from elsewhere in Gondwana and may permit the recognition of a distinctive lineage. The presence of the genus in Argentina in the earliest Permian is an important palaeobiogeographical observation that raises questions about the probable migration routes of the genus from the western Gondwanan South American margin to eastern Australia and India. The Precordilleran region appears to be the likely site of the first appearance of Trigonolrela. Species with relatively simple costae appeared first. These gave rise to more complex species with a more elaborate costal pattern indicating an evolutionary progression through time.<br /

Nuevos hallazgos de invertebrados marinos en el Mississippiano? de la Sierra de las Minitas, provincia de La Rioja, Argentina

La sucesión sedimentaria conocida como Formación Jagüel aflora en la Sierra de Las Minitas unos 20km al sudoeste de la localidad de Jagüé (La Rioja, Argentina), y está integrada por pelitas y areniscas vinculadas con diamictitas glacigénicas que se extienden desde el Devónico Medio al Mississippiano. Estas sedimentitas muestran una compleja historia estructural y se encuentran fuertemente plegadas e intruidas por cuerpos ígneos por debajo de la discordancia angular de Agua de Carlos, que las separa de los depósitos pennsylvanianos de la Formación Río del Peñón. Una asociación de braquiópodos, bivalvos, crinoideos, nautiloideos, gasterópodos, hyolithes, conularias y ostrácodos, se ha registrado en las proximidades de Agua Quemada al suroeste de la sierra. Los braquiópodos están representados fundamentalmente por rhynchonellidos, siendo la especie dominante Azurduya cingolanii Cisterna e Isaacson acompañada de Azurduya chavelensis? (Amos) y Azurduya? sp., y muy escasos Productidae y Chonetidae. Los bivalvos identificados incluyen Phestia sp., Malimania? sp. y una nueva especie de Palaeoneilo, junto con Myalinidae, Pectinidae y Anomalodesmata. Preliminarmente se observa que tanto los braquiópodos como los bivalvos presentan marcadas diferencias con aquellos identificados en la Formación Malimán y en los afloramientos más septentrionales de la Formación Jagüel (originalmente Formación Agua de Lucho). En dichas unidades la fauna se ha referido a la Biozona de Protocanites scalabrinii-Azurduya chavelensis, y está caracterizada por el predominio de Azurduya chavelensis (Amos), Yagonia furquei Taboada y Shi, acompañadas de Septosyringothyridinae n. gen.?, Palaeoneilo subquadratum González, Posidoniella malimanensis González, Malimania triangularis González y Sanguinolites punillanus González. Un exhaustivo análisis de la asociación faunística aquí reportada junto con evidencias palinológicas en estudio permitirán comprender la relación temporal entre estas faunas y mejorar el esquema de correlación para el contexto estratigráfico del área considerada.Sesiones libresFacultad de Ciencias Naturales y Muse

Dataset

Presence-Absence dataset of bed-level resolution samples from the Bashkirian and Moscovian-Kasimovian of Western Argentin