Hispanic Corridor: its evolution and the biogeography of bivalve molluscs

DAMBORENEA, S.E.

Advances in Jurassic Research 2000

Trans Tech Publications

Lugar: Zurich; Año: 2000; p. 369 - 379

An updated set of biogeographic data for bivalve molluscs is analysed to contribute to the understanding of the development of the Hispanic Corridor during Late Triassic to Middle Jurassic times. The succession of Simpson similarity coefficients between the western Tethys (s.s.) and several cratonic regions of the eastern Pacific shows "pulses" of increased similarity during that time, prior to the Bajocian. These range from Sinemurian to Toarcian according to the areas considered. Conversely, areas located within the same regions show only minor fluctuations. Since not all ecological types are equally represented in the biotic interchange along the Corridor, a shallow intermittent marine connection which preceded rifting by millions of years is indicated. Benthonic bivalve taxa, and especially epifaunal stocks, some of which can be followed "step by step", show this pattern clearly. Data suggest that this connection acted as a filter, allowing the passage of on-shore species while being an effective barrier for off-shore species.