In summary, the basal Unit 1a provides the most diverse range of microfossils and the highest order of microfossil diversity as additionally shown by bore-hole predation marks which were found on Reticypris sp. carapaces (Fig. 5). This generally points to the presence of a relatively deep and freshwater body in agreement with the sedimentary findings. However, the marked abundance of juvenile D. spinosa and small numbers of D. whitei suggest that rapid changes in the lacustrine environment may have also occurred after a freshwater incursion, perhaps due to oscillations in lake level or temperature, or rapid escalations in salinity from the dissolution of surface salts (De Deckker, 2002).