THE ARCHAEO-ENTOMOLOGICAL INTEREST OF ANCIENT WELLS: GALLO-ROMAN PALAEOENVIRONMENT AT CLOS-PAUL RECONSTRUCTED FROM COLEOPTERAN REMAINS (CHARLEVILLE-MEZIERES, ARDENNES)

摘要

Analyses of fossil insect assemblages (mainly Coleoptera) contained in the sedimentary infilling of ancient wells enable to elaborate very precise palaeoenvironmental reconstructions. This type of structure catch in huge numbers epigeous wandering insects, along with flying insects. Moreover, contrary to natural depositional contexts, insect assemblages accumulated at the bottom of wells do not contain any taxa associated with the depositional site itself, because the vast majority of insects are not able to durably colonize this type of environment. Insect assemblages yielded by wells are therefore predominantly made of beetles that reflect the immediate surroundings of the structure, whereas insect assemblages yielded by natural deposits are sometimes made of abundant aquatic and riparian taxa that blur the image of the extra-local environment. Wells provide also taphonomic conditions that are favourable to long term conservation of Coleopteran remains. The example of Clos-Paul Gallo-roman well shows to what extent Coleopteran assemblages from ancient wells may be taxonomically diverse and hence may provide a detailed picture of the palaeoenvironment. This well was obviously located in a dense forest environment, as suggested by the overwhelming dominance of xylophagous, saproxylophagous and sciaphilous Coleoptera, and not in a grassland environment as could be expected for a structure which could have been used to water domestic cattle.