Diversity and Biostratigraphy of the late Oligocene-late Miocene sand dollars (Echinoidea: Scutellina) of Argentina and Uruguay.

DEL RÍO CLAUDIA JULIA; MARTINEZ, SERGIO

REVISTA DE BIOLOGíA TROPICAL

REVISTA DE BIOLOGIA TROPICAL

Lugar: Turrialba; Año: 2021 vol. 69 p. 35 - 50

0034-7744

An updated synthesis of the taxonomic composition of the late Oligocene-late Miocene scutellines of Argentina and Uruguay was done. The group is represented by 14 species belonging to six genera. A detailed survey of their geographic and stratigraphic provenance was carried out, and four assemblages were identified. Numerical dates of the Neogene marine rocks obtained during the last years allowed to place them in a chronological scheme: ?Iheringiella? sp. A is restricted to the late Oligocene, the genera Camachoaster and ?Eoscutella? and the species Monophoraster telfordi to the early Miocene, Abertella gualichensis and A. miskellyi to the middle Miocene, and M. duboisi, Amplaster coloniensis and A. ellipticus to the late Miocene. Non-lunulate scutellines are not restricted to the late Oligocene as previously supposed. The oldest occurrence of the genus Monophoraster corresponds to the early Miocene, and along withIheringiella are long-living taxa that embrace the 25. 3Ma-18.1 Ma (I. patagonensis) and ca. 15 Ma- 6.48 Ma (M. darwini) intervals. The presence of Iheringiella in the early Miocene of northeastern Patagonia is corroborated, reaching there its northernmost distribution. M. darwini expands its temporal range from the late Miocene (where previously thought to be restricted)back to the middle Miocene, since this is the species yielded in the largely known and discussed ?Monophoraster and Venericor Beds?. There is a very good correspondence among the numerical ages, molluscan biozones and scutelline assemblages