PALEOENVIRONMENT AND TAPHONOMY OF DINOSAUR TRACKS IN THE VECTIS FORMATION (LOWER CRETACEOUS) OF THE WESSEX SUBBASIN, SOUTHERN ENGLAND

Reptilian ichnofossils are documented from three levels within the coa stal lagoonal Vectis Formation (Wealden Group, Lower Cretaceous) of th e Wessex Sub-basin, southern England (coastal exposures of the Isle of Wight). Footprints attributable to Iguanodon occur in arenaceous, str ongly trampled, marginal lagoonal deposits at the base of the formatio n, indicating relatively intense ornithopod activity. These were rapid ly buried by influxes of terrestrial and lagoonal sediment. Poorly-pre served footcasts within the upper part of the Barnes High Sandstone Me mber are tentatively interpreted as undertracks. In the stratigraphica lly higher Shepherd's Chine Member, foot casts of a small to medium-si zed theropod and a small ornithopod originally constituted two or more trackways and are preserved beneath a distinctive, laterally persiste nt bioclastic limestone bed, characterised by hypichnial Diplocraterio n. These suggest relatively low rates of dinosaurian activity on a low salinity, periodically wetted mudflat. Trackway preservation in this case is due to storm-induced shoreward water movements which generated influxes of distinct ive bioclastic lithologies from marginal and off shore lagoonal settings. The rapidly-deposited footprint-fills occasio nally contain fully articulated shallow burrowing bivalves. (C) 1998 A cademic Press.