MOLUSCO S DEL TERCIARIO INFERIOR ("MAGALLANENSE") DE LA ISLA GRANDE DE TIERRA DEL FUEGO (REPUBLlCA ARGENTINA)

Abstract

In the Isla Grande of Tierra del Fuego, a conglomeradic sandstone contains many bivalves, gastropods and few foraminifers, corals, brachiopods and palynomorphs. The fossiliferous localities Cerro Castillo (San Julio Farm) and a quarry at La Federica Farm yielded the following species: Flabellum cf. F cuneiforme wailesi Conrad, Pachymagas cf. P. venter (Ih.), Nucula (Leionucula) grandis n. sp., Glycymeris ef. G. cuevensis Ih., Cucullaea (Cucullona) fueguensis n. sp., Cucullaea [Cucullona] alta Sow., Cardiocardita inaequalis (Phil.), Pleuromeris elegantoides (Ortmann), Ostrea philippii Ortmann, Ostrea torresi Philipni, Modiolus ameghinoi lh., Miltha promaucana crucialis (Ih.), Eurhomalea ef. fuenzalidai (Philippi), Calyptraea sp.,. Calyptraea ef. C. merriami (Ortmann), Polinices (Euspira} santacruzensis Ih., Polinices {Eutpira} sp., "Nassa" fueguina Stcinmann and Wilekens, Austrocominella fueguensis Ihering, "Chenopus" santacruzensis Ihering, Struthiolarella densestriata (Ih.), Turritella ambulacrum sylva Ihering, Trophon? sp., "Verconella" iheringi (Steinmann and Wilckens), Tudicla n. sp., Miomelon spp., and "Actaeon" chilensis Philippi. This fauna has close relationships with those of the Eoeene and Oligoeene Formations in Patagonia and southern Chile; in less proportion there are relationships with New Zealand and the Atlantie region of North Ameriea. The characteristies and specific relationships point an age between the Eocene and early