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Foraminiferal communities in the Cenozoic shelf deposits of the North American Atlantic Coastal Plain exhibit little unity during almost 55 million years of successive transgressions and regressions. Transgression communities are composed of a dynamic mixture of immigrants and newly evolved species. During regressions, species within these communities either became extinct or emigrated. Some emigrants returned during subsequent transgressions, but many did not. The neritic species of the Atlantic and Gulf continental margins constitute a species pool. Immigrants and emigrants transferred into and out of the species pool, while extinctions and originations repeatedly altered its species composition. While the results indicate a lack of local community unity, at the same time they demonstrate the necessity of a species pool to sustain species diversity., Some ecological communities have been regarded as a kind of superorganism or unit wherein the component species are closely associated by numerous biotic interactions. Others have been considered as a [...]

Agglutinated forminifera have been recovered from siltstones in the Walidiala Valley, Taoudeni Basin, West Africa. Associated faunas suggest an Early Cambrian age for these strata. These now earliest known unequivocal formainifera help constrain hypotheses concerning the origin of skeletalization at the beginning of the Phanerozotic., DISCUSSIONS CONCERNING THE APpearance of skeletonization near the base of the Cambrian [about 550 Ma (million year ago)] [1] are often restricted to metazoans and take little account of the [...]

Geographic Origin of Benthic Foraminiferal Species THE CENTERS OF ORIGIN OF SPECIES have been discussed in the literature of biogeography and evolution for over a century. The classic scenario maintains [...]

Analysis of species durations is useful for understanding the interplay of ecological and evolutionary forces (1). Among marine organisms the benthic foraminifera are widely distributed, and they have a well [...]