TEMPORAL AND GEOGRAPHICAL DISTRIBUTION OF TERTIARY SOUTH AMERICAN SAND DOLLARS (ECHINODERMATA: ECHINOIDEA: CLYPEASTEROIDA)

MARTINEZ SERGIO,; DEL RIO, CLAUDIA JULIA; MOOI, SERGIO

LONDRES

Congreso; 3° International Paleontological Congress; 2010

During the Tertiary, South American scutelline sand dollars were represented by at least three families(Monophorasteridae, Mellitidae, Abertellidae), plus a genus with uncertain affinities (Iheringiella). The aim ofthis survey is to reevaluate stratigraphical data concerning these taxa. The Monophorasteridae is an extinctclade restricted to southern South America. Monophoraster is represented by M. darwini (Argentina, MiddleMiocene-early Late Miocene) and M. duboisi (Argentina, Uruguay, early Late Miocene). M. darwiniapparently also occurred in Chile, where ¡ts age remains unclear, although undoubtedly not Eocene asoriginally stated. The other genus in the family, Amplaster, contains three species: A. alatus (Argentina, EarlyMiocene-early Late Miocene; Uruguay, early Late Miocene), A. coloniensis (Uruguay, early Late Miocene),and A. ellipticus (Uruguay, early Late Miocene). The family Mellitidae is represented by Leodia divinata fromthe Early Pliocene of Venezuela, and Encope species from the Pliocene of Chile. The Abertellidae isrepresented in South America by two species: Abertella pirabensis (Brazil, Early Miocene), and A.gualichensis (Argentina, early Middle Miocene). Iheringiella patagoniensis is limited to the Late Oligocene ofsouthern Argentina. The early Late Miocene was the time when the máximum diversity of sand dollars wasreached. The absence of Pliocene deposits along the southwestern coast of South America prevenís us fromknowing how these faunas changed during that period. Pleistocene fossils represent a modern fauna.