Palaeobiogeography is a complex subject which processes information
provided by both Biology and Earth Sciences. It is conceptually and
philosophically equivalent to neobiogeography. Nevertheless, its methods
are somewhat different, since it is limited by the incompleteness of the
fossil record. On the other hand, it has direct access to the time
dimension, a key ingredient of organic evolution. Mesozoic benthonic
mollusks, and especially bivalves, have a great potential for
palaeobiogeographical analysis due to their commonly good preservation,
abundance, diversity and high dispersion potential at the larval stage.
From a merely descriptive point of view, the analysis of their
distribution shows latitudinal gradients and distributional patterns,
both at regional and global scales, which are the basis for the
recognition of biochoremas or palaeobiogeographical units of different
ranks. Moving forward towards a causal
palaeobiogeography, these organisms also provide interesting insight
into particular biogeographical questions, such as bipolarity and its
origin. The evolution in time of the
recognized biochoremas can be discussed in relation to palaeoclimas and
extinction events. Finally, some of the results obtained from the
analysis of the distribution of past
bivalve biotas were even used to propose and discuss the development of
marine corridors and argue about the distribution of continents in the
past.