ABSTRACT
The relationships between surface area and biodiversity expressed in island biogeography or the present geographical distribution of biodiversity (strikingly shown in latitudinal diversity gradients peaking in the tropics and decreasing towards the poles) have been studied under the general heading of ecological biogeography. This is aimed at interpreting spatial distributions of assemblages relative to ecological parameters. Such an approach may, however, be too rigid because causal explanations of observed biotic distributions must take into account both ecological and time-related elements. Ecological analyses can be carried out at different spatial scales or levels of perception (see the extensive discussion in Rosen, 1988a), including the regional and continental scales that are most often considered in palaeobiogeography. In fact, it is extremely difficult to generalize diversity analyses at the community level at the scale of the overall diversity of an entire sedimentary basin or province.
