Pilotstudie zur Evolution jungpaläozoischer Insekten im Souss-Becken, Marokko

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The insect-biostratigraphy has proven as one of the most precise methods for the subdivision and correlation of Late Palaeozoic terrestrial deposits in Europe and Nord America. The method is based on the temporal sequence of colour patterns on the wings of blattid insects (cockroaches), family Spiloblattinidae. They are regarded as chrono-species and used for the definition of the insect-biozones. Unfortunately, basic question regarding the palaeobiology and evolution remain completely open so far. These essentially concern the kind of evolutionary processes, areal dynamics of genera and species in Euramerica (palaeobiogeography and migration pattern) as well as the palecology (synecology) of spiloblattinids, i.e. the relationships to the whole entomofauna and to the flora as well. In this pilot-study of a larger future project the 1,200 m thick profile of unusual insect-rich Carboniferous deposits of the Souss basin in Morocco should be analysed whether it is suitable to test the following alternative hypothesis in regard to the abovementioned basiuc questions:Hypothesis 1: Are the changes in the colour pattern a continuous process in respect of phyletic evolution or anagenesis/gradualism respectively of chronoclines of single forms which must regarded as long living biospecies, or is it alternatively punctualism?Hypothesis 2: Is the chronological sequence of changing colour pattern (controlled by genetic factors) in the whole euramerican distribution area isochronous or appear similar colour pattern in different regions at different times?Hypothesis 3: Collection of insects in the Souss basin has so far delivered solely blattids, among them dominating xeromorphic opsiomylacrids. Is it a sampling bias or is it a taphonomic effect or is it caused by the still pronounced differentiation of lowland/upland or coastal/inland entomofaunas?In the Central European Carboniferous and Permian basins insect-containing horizons are only sporadically intercalated in several thousand meters thick profiles. Calculated on isotopic ages horizons with spiloblattinids follow one another with about 500,000 y to 1 My. In this sequence zone-species show distinctly pronounced different colour pattern. The insect bearing sediments of the Souss basin have a thickness of 1,200 m. Sedimentation rates of 2 to 5 mm per year assumed, this profile represent about 250,000 to 600,000 years. Insects have already been found in the lowermost and uppermost parts of the profile. The dense sequence of lake horizons will allow for continuous sampling of spiloblattinids. Based on that it will be possible, to determine the way of colour pattern changes through time. On the whole, a significant contribution to the evolution of Late Palaeozoic insects and of here environments, to evolution theories and to the methodology of biostratigraphy in terrestrial sequences could be expected.