Assessing mechanisms of environmental change: Palynological signals across the Late Ludlow (Silurian) positive isotope excursion (δ13C, δ18O) on Gotland, Sweden

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Morphometric analysis of proposed evolutionary lineages of Early Devonian land plant spores.

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Morphometric analysis of proposed evolutionary lineages of Early Devonian land plant spores

peer reviewedEarly Devonian miospore assemblages from 'La Gileppe' (Eastern Belgium) include five varieties of trilete spore belonging to the genus Emphanisporites. These five varieties show a continuous variation of their morphological characteristics. The variation in morphological characteristics can be related to the evolution of morphological features and allows us to define the Emphanisporites micromatus Morphon. A statistical evaluation of this population highlights the interdependence of almost all morphological parameters. This study proves the increase in size of ornamental and structural parameters over several million years. The biometric changes and the progressive replacement of older morphotypes by younger ones indicate that a temporal link exists between these different varieties. Two phylogenetic hypotheses for the E. micromatus Morphon are proposed. This morphological evolution is so far observed only on the Eastern Old Red Sandstone Continent and defines a palaeophytogeographic sinuosus-zavallatus Province

Reevaluation of the late Cambrian– Early Ordovician acritarch Nellia acifera GOLUB & VOLKOVA

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Acritarch distribution along an inshore¬offshore transect in the Gorstian (lower Ludlow) of Gotland, Sweden.

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Population dynamics of galeate acritarchs at the Cambrian-Ordovician transition in the Algerian Sahara

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“What” and “where” in the human auditory system

The extent to which sound identification and sound localization depend on specialized auditory pathways was examined by using functional magnetic resonance imaging and event-related brain potentials. Participants performed an S1–S2 match-to-sample task in which S1 differed from S2 in its pitch and/or location. In the pitch task, participants indicated whether S2 was lower, identical, or higher in pitch than S1. In the location task, participants were asked to localize S2 relative to S1 (i.e., leftward, same, or rightward). Relative to location, pitch processing generated greater activation in auditory cortex and the inferior frontal gyrus. Conversely, identifying the location of S2 relative to S1 generated greater activation in posterior temporal cortex, parietal cortex, and the superior frontal sulcus. Differential task-related effects on event-related brain potentials (ERPs) were seen in anterior and posterior brain regions beginning at 300 ms poststimulus and lasting for several hundred milliseconds. The converging evidence from two independent measurements of dissociable brain activity during identification and localization of identical stimuli provides strong support for specialized auditory streams in the human brain. These findings are analogous to the “what” and “where” segregation of visual information processing, and suggest that a similar functional organization exists for processing information from the auditory modality