DATOS PALEOBIOGEOGRAFICOS DE ALGUNAS ASOCIACIONES DE FORAMINIFEROS, OSTRACODOS Y CAROFITAS DEL JURASICO MEDIO Y EL CRETACICO INFERIOR DE ARGENTINA

Eduardo A. Musacchio

Abstract


The present paper deals with cosmopolitism and provincialism evidences in several marine and non-marine calcareous microfossils assemblages, principally from the Andean Region.
A Lower-Middle Callovian fauna with Reineckeia sp., including 51 species of benthonic Foraminifera -principally nodosarids- and 10 species of Ostracoda, and two Hauterivian assemblages with Holcoptichytes neuquensis and Crioceratites spp., both including 54 species of Foraminifera -principally nodosarids and 25 of Ostracoda are considered. In each assemblage more than 50% of the foraminifera species from those that can be adequately studied, have a large geographical distribution and therefore the provincialism evidences are poor.
On the other hand more than 50% of the Hauterivian ostracods are, up to the present, unknown in other regions, suggesting an Andean provincialism. These Hauterivian ostracods assemblages have clear affinities with others of Neocomian age from South Africa.
The ubicuity and the shorter life time of ostracods species in relation to foraminifera, in conection with the more early provincialism in ostracods, discussed.
Peculiar evidencesof cosmopolitism and dispersion in Lower Cretaceous non-maríne Andean and Subandean assemblages of ostracods and charophytes are analyzed. In this regards the interest of several species of Cypridea (Ostracoda) and clavatoracean (Charophyta) is emphasized.
The chronological approach to the world time scale, on the basis of the cosmopolitan taxa is discussed.

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