PALEOBIOGEOGRAPHICAL AFFINITIES OF ALBIAN AND CENOMANIAN SHALLOW-WATER, NON-RUDISTID BIVALVE FAUNAS IN THE COLOMBIAN EASTERN CORDILLERA (SOUTH AMERICA)

This presentation is dedicated to Annie Dhondt (1942 – 2006), who contributed much to our research on Cretaceous bivalves.

We present results from a paleobiogeographical study of Albian and Cenomanian shallow-water, non-rudistid bivalve faunas from the Eastern Cordillera of Colombia. Our data are based on the taxonomic identification and revision of material from 148 sites in the Simití Fm., Areniscas de Chiquinquirá Fm., San Gil Superior Fm. and Churuvita Fm. The pteriomorphs (ostreids, pectinids and bakevelliids) are the most diversified group (24 species), followed by the palaeoheterodonts (2 species). Common forms are Rhynchostreon squamatum (=R. mermeti), Ilymatogyra africana, Ceratostreon flabellata, ?Gyrostrea delettrei, Costagyra olisiponensis, Oscillopha syphax, Plicatula auressensis, Camptonectes striatopunctatus and Pseudoptera gregaria.

A list of 25 middle Albian–Cenomanian species from Colombia shares: 16% of species from the Albian–Cenomanian of Texas and Central America, 32% with the Albian–Cenomanian of Peru, 36% with the upper Aptian and Cenomanian of Morocco, 48% with the Albian–Cenomanian of Algeria, 44% with the Cenomanian of Tunisia, and 28% with the Albian of Sardinia.

A list of 21 Cenomanian species of Bakevellidae, Pectinidae, Syncyclonemidae, Neitheidae, Ostreidae, Gryphaeidae and Palaeolophidae from Colombia was compared with lists for Texas (Caribbean Tethys province), Morocco and Algeria (Western Mediterranean Tethys Province), and France (Northern Temperate Realm, Aquitanian and Paris basins), using Jaccard (J), Dice (D) and Simpson’s (S) similarity coefficients. North Africa shows the highest faunal similarity (J 34.78–42.85, D 51.61–60, S 80–63.15), followed by France (J 15.55, D 26.92, S 33). Texas had the least similarity with Colombia (J 3.92, D 7.5, S 9.52).

High similarity values between Colombia and the North Africa appear to be due to the presence of identical oyster faunas. Moderate similarity between bivalve faunas from Colombia and France apparently result from shared cosmopolitan species. Our results agree with the presence of the Tethys Circumglobal Current running westward along the southern margin of the Tethys, and with the presence of a weaker gyre circulation analogous to the Gulf Stream.