The Hauterivian-Barremian lignitic bone bed of Angeac (Charente, south-west France): stratigraphical, palaeobiological and palaeogeographical implications
Résumé
This paper provides the sedimentological, palaeontological and biostratigraphical characteristics of a newly discovered lignite-bearing sedimentary succession in western France. The lignitic bed, which is reminiscent of some Wealden facies in southern England, is located in Angeac in the Charentes region. The plant remains occur as three-dimensionally preserved mesofossils (cuticles, charred ferns and seeds, cones and twigs) and larger pieces of wood. The deposits contain variable amounts of such material and at one horizon in particular, an outstanding accumulation of dinosaur teeth and bones. Among the vertebrate remains are the longest sauropod femur (ca. 220 cm) yet found and bones representing an ornithomimosaur herd of at least eight individuals. The palynomorph content of the clay associated with the bones and lignitic material indicates a Hauterivian Barremian age. The abundance in the fossil assemblage of freshwater unionoid bivalves, some preserved in life position, the presence of freshwater algae, and the scarcity of brackish or marine species indicate that the depositional environment was a swamp only very occasionally connected to the sea. The forest bordering the swamp was dominated by cheirolepidiaceous trees co-occurring with a diverse assemblage of ferns