L’ambre campanien du Mas d’Azil (Ariège, France) : gisement, micro-inclusions, taphonomie

Abstract

The amber of Le Mas d’Azil (Ariège, France), fashioned by the Magdalenian people of Le Mas d’Azil cave, was collected in clay levels rich in Cupressinoxylon Göppert, of the Campanian Labarre Sandstone Formation, which is a large deltaic set, infilling the sub-Pyreneean trough. The amber pieces are small and resemble modern resin exudates on coniferous trunks. We describe following micro-inclusions. Actinomycetes: Cardonia stellata, nov. gen., nov. sp., located close to the surface of amber pieces, is abundant and displays chains of conidia and isolated aleuriospore. Nocardiopsis ? sp. D is rare. Actinomycete “de type Salignac” is abundant. Its filaments often display a tendril shape, which seems to prelude to a mycelium fragmentation. Other bacteria: Leptotrichites resinatus Schmidt (Schmidt and Schäfer, 2005), poorly represented, is more variable than the already known material; cf. Sphaerotilus sp., very abundant, also displays differences with the Cenomanian “Sphaerotilus sp.”. Eukaryotes: one fungal filament, and a group of spores, pollens or cysts. Inorganic inclusions: gas bubbles, pseudo-protists of B and C? types, and tiny, transparent, cubic crystals. It seems that most of the quoted prokaryotes were resinicolous organisms, able to settle on the surface of the exudate, and grow in the resin, after inoculation either by a contact with the substrate, or by an anemophilic dispersion of spores. This “taphonomic way” seems here to be more general than trapping.