Análisis criptopaleontológico del lapidario de Teofrastro (s. III a.C.)

La obra"Perì líthon" o"Tratado de Piedras" de Teofrasto, es considerado el texto más antiguo conservado sobre minerales y rocas, aunque haya llegado hasta nosotros incompleto. En este trabajo se analiza su contenido comparándolo con el de otros lapidarios antiguos y se concluye que once de las piedras que refiere y que vienen indicadas con nombres geográficos o crípticos son fósiles de plantas, vertebrados o químicos. Por eso, esta obra debe considerarse también como el tratado más antiguo que conocemos sobre paleontología, pues además de los fósiles que menciona, en ella se alude expresamente al proceso de fosilización. Palabras clave: Criptopaleontología

Lower-Middle Cambrian Palaeogeography of the Northern Spain

[Resumen] Se analizan los datos litoestratigráficos y el contenido bioestratigráfico de la secuencia del Cámbrico Inferior y Medio en una veintena de localidades de la región Cantábrica, Sierra de la Demanda y Cadenas Ibéricas (norte de España). Estos datos indican la existencia de condiciones semejantes durante el Cordubiense y parte del Ovetiense (Cámbrico Inferior basal) en todo el área; con cuencas marinas someras de alta energía y transporte de grandes cantidades de sedimentos siliciclásticos. No obstante, una delgada plataforma carbonatada se instauró en la parte meridional de la región cantábrica durante el Cordubiense superior dando lugar a condiciones menos abiertas, a la vez que nos indica que los cambios faciales no fueron coincidentes con las directrices hercínicas actuales. La extraordinaria extensión de los sedimentos siliciclásticos, incluyendo la Montaña Negra, el espesor de los mismos y las~directrices de corrientes nos indican una extensa área erosionándose hacia el N.E., que bien pudo ser un sector afín al área fuente del Macizo Central francés. A partir del Ovetiense superior ser va instalando una plataforma carbonatada en todo el área que presenta diferentes facies según las localidades estudiadas, obteniendo así un modelo paleogeográfico más complejo. Los límites de cada unidad facial serían diacrónicos como se deduce del contenido en trilobites. En la región Cantábrica se distinguen cuatro facies caracterizadas por diferentes secuencias litológicas y que se denominan: facies Los Bam·os, facies Beleño, facies Vegadeo y facies Alto Stf. Las líneas de cambio entre las dos primeras facies siguen más o menos las directrices hercínicas, mientras que las otras dos son aproximadamente oblicuas. Para el Sistema Ibérico, el modelo de sequencias faciales es más homogéneo y diferente al cantábrico. El recubrimiento por sedimentos siliciclásticos de esta plataforma acontece diacrónicamente durante el Cámbrico Medio, siendo la parte meridional de la región cantábrica la última en recibir sedimentos siliciclásticos.[Abstract] The Lower-Middle Cambrian lithostratigraphical and biostratigraphical data of twenty localities from Cantabrian region, Demanda and Iberian Chains are analyzed. Those data suggest the existence of similar conditions in the area during the Cordubian and Ovetian ages (early Lower Cambrian) which are characterized by the transport of áhigh volume of siliciclastic sediments and its deposit in a shallow marine shelf. Only a reduced carbonate shelf was placed in the meridional part of the Cantabrian region during the Upper Cordubian. These restricted conditions permit us to know the obliquity of the facial change lines in relation to the posterior hercynian directions. The widespread range of the exposed siliciclastic sediments, including the Montaigne Noire, their thickness and the palaeocurrent directions suggest an extensive area source forward the northeast that probably coincided with a sector adjacent to the present French Central Massif. From the Upper Ovetian to the early Middle Cambrian a carbonate platform developped in the whole area with deposits of facial units varying in the different sequences of each locality studied resulting in a more complex palaeogeographical model. The boundaries of this facial units are diachronic as it is deduced from their content of benthic trilobites. Four lithological sequences named: Los Bam'os, Beleño, Vegadeo and Alto Szlfacies are distinguished in the Cantabrian region. The facies change lines between the two first facies are parallel to the hercynian structures, while the other two ones are oblique. In the Iberian Ranges, in this time, the facies are more homogenous and different from the facies in the Cantabrian region. The disappearence of the carbonate platfform happened diachronically during the Middle Cambrian, being the southern part of the Cantabrian region the last one to receive siliciclastic sediments [Resumo] Apresenta-se neste trabalho um estudo geológico de pormenor relativo asubsidencia mineira provocada pela explora~ao de carvao na Mina de Germunde (Bacia Carbonífera do Douro, NW de Portugal). Os autores analisam e discutem os diferentes aspectos litológicos e estruturais que condicionam a localizaao das descontinuidades induzidas pela subsidencia, que afloram asuperficie do terren

The negligence and lazy of the administration: The greatest danger to the conservation of unique sites of exceptional preservation

An example is given of one of the most important sites in the Spanish fossil record, such as the almost a hundred moulds of ancient jellyfish of hydrozoan Medusozoa, Cnidaria, exceptionally preserved in an arkosic greywacke bedding plane of the Corduban/Terreneuvian Epoch (lowermost Cambrian) in the municipal district of Constantina (Seville). In spite of its scientific-patrimonial importance and the fact that it has been brought to the attention of the Andalusian autonomous administration for more than twenty-five years, it has still not been the object of an adequate legal protection figure. This lack of interest or bureaucratic slowness is causing an irreparable loss in many of its elements affected by erosion and the passage of time. A series of urgent actions are also proposed to mitigate the current deterioration of the site and favour its conservation. Se expone el ejemplo de uno de los yacimientos más importantes del registro fósil español como son los casi cien moldes externos de antiguas medusas de Medusoz oa, Cnidaria, tipo hidrozoo, conservadas en el techo de un estrato de grauvacas arcósicas de edad Cordubiense/Terreneuviense (Cámbrico inferior temprano), en el término municip al de Constantina (Sevilla). A pesar de su excepcional idad científi co-patrimonial y de haber sido puesto en co nocimiento de la administración autonómica andaluza desde hace más de veinticinco años, todavía no ha sido objeto de una fi gura de protección legal adecuada. Esta falta de interés o de lentitud burocrática está ocasionando una pérdida irreparabl e en muchos de sus elementos, afectados por la erosión y el paso del tiempo

Atopidae (Trilobita) in the upper Marianian (Cambrian Series 2, Stage 4) of Iberia

New atopid trilobites are described from the early Cambrian Cumbres beds and Herreriás shale of northern Huelva Province (Andalusia, Spain) and are dated as middle-late Marianian (Cambrian Series 2, Stage 4). New specimens of Atops calanus Richter and Richter, 1941 are described and the Laurentian species Pseudatops reticulatus (Walcott, 1890b) is recognized for the first time in the Mediterranean subprovince. The associated trilobite assemblage studied herein suggests an age close to the base of Cambrian Stage 4

The Cambrian of the Iberian Peninsula : an overview

This work is a brief overview of the Cambrian in the Iberian Peninsula, along with an updated review of lithostratigraphic and biostratigraphic data. A Cambrian correlation chart between the different stratigraphical units that have been established in the Iberian Peninsula is given. We also reappraise the Lower and Middle Cambrian regional stages in the light of new palaeontological data, and the different biozonations proposed with several palaeontological groups

Revisión sistemática y bioestratigrafía del género Alueva Sdzuy, 1961 (Ellipsocephalidae, Trilobita, Cámbrico).

Se revisa la sistemática del género Alueva Sdzuy, 1961 y de las tres especies incluidas en él: Alueva undulata Sdzuy, 1961, Alanisia hastata Sdzuy, 1958, y Strenuaeva sampelayoi moratrix Sdzuy, 1958, todas ellas definidas en la localidad zaragozana de Murero. Alueva venulosa Dean, 2005 se considera un sinónimo subjetivo más reciente de Protolenus dimarginatus Geyer, 1990. También se revisan los hallazgos de Alueva hastata en la Sierra de Córdoba, Cordillera Cantábrica y, posiblemente, los de las Montañas del Taurus (Turquía). Con los datos actuales, este género parece ser endémico de la Subprovincia Mediterránea. Alueva presenta una distribución muy breve, desde un punto de vista bioestratigráfico, en niveles entorno al límite Cámbrico inferior medio, en el sentido clásico, concretamente desde el techo del Bilbiliense superior y la mayor parte del Leoniense inferior en la escala cronoestratigráfica establecida para el Cámbrico español. Estos niveles son correlacionables con los que en la actualidad se están estudiando para situar el límite entre las Series 2 y 3 del Cámbrico por la ISCS

The trilobite Serrodiscus Richter & Richter from Iberia, with systematic review of the genus and its international correlation through the Cambrian Series 2

Serrodiscus is considered one of the first trilobite genera showing global distribution during the Cambrian and a key component for the international correlation of this period. However, this genus encompasses many poorly documented species, ambiguous diagnoses or characters that depend on taphonomy and deformation based on one single specimen. Thus, in the present work, we carry out a systematic overview of the genus, evaluating the taphonomic and deformational variability of a large number of specimens from the same locality and horizon. In addition, and due to the difficulty of making synonymy decisions, closely related species are grouped into three different groups taking into consideration morphologic, stratigraphic and palaeobiogeographic data: bellimarginatus group, scattered along Avalonian and western Gondwanan margins; speciosus group, extending over the Laurentian domain; and daedalus group, being restricted to eastern Gondwana (Australia), North China and, partially, Siberia. Besides, the regional correlation through the early Cambrian of Iberia is arranged, describing specimens from both Ossa-Morena and Central Iberian zones, with a time interval restricted to the upper Marianian Stage. Regarding the biostratigraphy and palaeobiogeography of the genus, Serrodiscus has been reported from Laurentia, Taconic Allochthon, Greenland, Baltica, western and eastern Avalonia, western Gondwana margin, Siberia, North China and eastern Gondwana, with a temporal distribution along with the Cambrian Series 2

Large-scale atmospheric circulation enhances the Mediterranean East-West tree growth contrast at rear-edge deciduous forests

Overlaid to a general reduction of European beech and sessile oak tree growth over the recent decades in the Mediterranean Basin, tree-ring records from western Mediterranean populations display a stronger growth decrease than eastern populations. We investigate here to what extent the impact of sustained atmospheric circulation patterns in summertime can explain the observed spatial patterns of tree growth. We use Canonical Correlation Analysis, a statistical method that identifies the coupled patterns that are optimally correlated between two multivariate data sets. A general change in growth trends, shifting from a general increase during the period 1950\ue2\u80\u931981 to a decrease during the last three decades (1982\ue2\u80\u932012), can be attributed to increasing summer temperatures, which exert a dominant and negative influence on growth in both tree species across sites. However, summer precipitation has gained importance for growth, coinciding with the intensification of the geographical polarity in climate conditions across the Mediterranean Basin. This intensification during the last three decades can be traced back to a strengthening of the Summer North Atlantic Oscillation (SNAO), which imparts an east-west dipole to summer climate in this region. Under predicted persistent stronger SNAO in the future, western populations would face harsher summer conditions than central and eastern rear-edge populations, due to decreasing precipitation and increasing temperatures in the western Mediterranean Basin. These results evidence the determinant role that changes in the atmospheric circulation patterns may play in the persistence of rear-edge temperate deciduous forests in the near future

Systematic and biostratigraphy of the genera Parasolenopleura, Badulesia, and Pardailhania in the Iberian Chains: a useful zonation for the Miaolingian Series (former middle Cambrian) in the Mediterranean region

The trilobite species of three genera included in the Family Solenopleuridae: Parasolenopleura, Badulesia and Pardailhania are revised. These genera have a great biostratigraphic interest due to their broad distribution in the Miaolingian Series (former middle Cambrian) of the Mediterranean Subprovince and because they constitute an evolutionary lineage, that facilitates an accurate regional correlation. Two of these genera (Pardailhania and Badulesia) have been used to define middle Cambrian zones in Spain (lower and middle Caesaraugustan, equivalent to the uppermost Wuliuan and the lower Drumian stages). Although, all authors have been using the same species to establish the Mediterranean biozonation of this interval time, the zone concept has been modified since Sdzuy's original idea. A thorough study of three localities from the Iberian Chains (Murero, Jarque and Villafeliche) have allowed us to revise the lower and middle Caesaraugustan zonation in the Iberian Chains and for extension, in the Mediterranean region by comparison with the other localities where those genera are recorded. We propose now a review zonation based on trilobite phylozones, including new stratigraphic and systematic data from the Iberian Chains in order to clarify the intercontinental correlation of this time interval