Palynology of the dinosaur-bearing Wealden facies in the natural pit of Bernissart (Belgium)

A palynological study of the dinosaur-bearing Wealden facies at a depth of 322 m in the "natural pit with Iguanodons" of Bernissart (Belgium) is presented. The palynomorphs of 16 clay and silt samples collected in 1878-1881 during the dinosaur excavations are of continental origin. The botanical affinities of the 85 palynological taxa are mainly ferns, gymnosperms and freshwater algae. Also encountered are pollen grains of angiospermous affinity (biorecord Superret-croton) whose germinal apparatus is questioned. The distinction between the biorecord Hauterivian-cactisulc and Cerebropollenites mesozoicus is discussed. It is suggested that the vegetation was distributed around the unstable lacustrine environment of the Bernissart area, in relation to the formation of the natural pit and local dissolution of deep anhydrites. Ferns, Taxodiaceae, freshwater algae and angiosperms lived close to the lake though gymnosperms were thriving on neighbouring hills. The occurrence of early angiosperms at Bernissart documents their development in disturbed and unstable environments during the Barremian-Aptian.