reservas, similares procesos metalogenéticos habrian actuado en el Paleozoico Inferior del Brea. La deformación y el metamorfisme regional hercinicos no han actuado en este sector como un importante reconcentrador de menas, y la mayor parte de indicios epigenéticos Many mineralizations, showings and geochemical anomalies de edad tardihercinicaestán relacionados alas células hidrotermales have b...

Because many survivors of mass extinctions do not participate in postrecovery diversifications, and therefore fall into a pattern that can be termed "Dead Clade Walking" (DCW), the effects of mass extinctions extend beyond the losses observed during the event itself. Analyses at two taxonomic levels provide a first-order test of the prevalence of DCWs by using simple and very conservative opera...

The phylogenetic relationships between the different groups of Paleozoic gnathostomes are still debated, mainly because of incomplete datasets on Paleozoic jawed vertebrate fossils and ontogeny of some modern taxa. This issue is illustrated by the condition of the glossopharyngeal nerve relative to the parachordal plate, the otic capsules and the metotic fissure in gnathostomes. Two main condit...

The Mesozoic lacustrine revolution (MLR) represents a major evolutionary event in the continental realm (Cohen 2003 ). The decline in taxic diversity at the family level in lacustrine environments that took place during the late Paleozoic–Middle Triassic was reversed later in the Mesozoic, with diversifi cation seeming to have continued to the Quaternary, although potential biases may have affe...

Several ranges encompassing more than 35,000 km 2 of Sonora, Mexico, contain distinctly lineated and foliated granitic and metamorphic rocks that constitute the lower plates of metamorphic core complexes. Penetrative deformation is characterized by gently dipping mylonitic foliation across which northeast trending stretching lineation is everywhere developed. Prominent northwest trending fractu...

The origin of the limbless caecilians remains a lasting question in vertebrate evolution. Molecular phylogenies and morphology support that caecilians are the sister taxon of batrachians (frogs and salamanders), from which they diverged no later than the early Permian. Although recent efforts have discovered new, early members of the batrachian lineage, the record of pre-Cretaceous caecilians i...

Distinct parts of limestones within the upper Paleozoic Auernig Group of the Carnic Alps, Austria and Italy, are characteristic of cool-water carbonates. The Carnic Alps were between 5 N and 10 S paleolatitude during the late Carboniferous, a position confirmed by dasyclad algae and fossil plants. The floral association, occurrence of coal seams, and absence of evaporites indicate a humid tropi...

Anomalous, large pipe-to-soil potentials (PSP) have been observed along a natural gas pipeline in eastern Ontario, Canada, where there is a major geological contact between the highly resistive rocks of the Precambrian Shield to the west and the more conductive Paleozoic sediments to the east. This study tested the hypothesis that large variations of PSP are related to lateral changes of Earth ...

Magmatic and stratigraphic settings exert a first order control on the formation of various mineral deposit types. Some sating are rich in mineral wealth while others are barren. Stratigraphic setting is of particular importance where stratif&m or stratabound minerill deposits are concerned x orebodies are commonly restricted to specific stratigraphic intervals. For example. within the area bou...