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The AAPG/Datapages Combined Publications Database

GCAGS Transactions


Gulf Coast Association of Geological Societies Transactions
Vol. 29 (1979), Pages 224-227

Relict and Expatriated Radiolarian Fauna in the Gulf of Mexico and its Implications

Richard Casey (1), Ken MeMillen (2), Richard Reynolds (3), Joan Mussler Spaw (4), Rudy Schwarzer (5), Joel Gevirtz (6), Mary Previous HitBauerTop (7)


The presence of living specimens of Spongaster pentas and related spongodiscid forms, Buccinosphaera invaginata, Collosphaera tuberosa and others in plankton and Quaternary sediment samples from the Gulf of Mexico is evidence of a unique radiolarian population that is composed in part of relict and expatriated radiolarian forms. These relict and expatriated populations may have survived in the Gulf because: 1) the closure of the Tethys Seaway by the uplift of the Panamanian Block isolated the equatorial and temperate Atlantic waters and blocked radiolarian faunas from entering the Pacific and Indian Oceans; 2) temperate and perhaps equatorial radiolarian faunas of the Pacific and Indian Oceans have contributed to the temperate and equatorial Atlantic radiolarian faunas since the closure of Panama; 3) the ability of relict and related forms to carry on symbiotic relationships with algal associates may have enabled these forms to adapt and survive. This information adds insight into our understanding the evolution and biostratigraphy of Cenozoic radiolarian faunas, and perhaps also Mesozoic and Paleozoic faunas.

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