Temporal and geographical distribution of the Tertiary South American sand-dollars (Echinodermata: Echinoidea: Cypeasteroida)

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

LONDRES

Congreso; 3° International Paleontological Congress; 2010

International Palaeontological Association

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 of this survey is to reevaluate stratigraphical data concerning these taxa. The Monophorasteridae is an extinct clade restricted to southern South America. Monophoraster is represented by M. darwini (Argentina, Middle Miocene-early Late Miocene) and M. duboisi (Argentina, Uruguay, early Late Miocene). M. darwini apparently also occurred in Chile, where its age remains unclear, although undoubtedly not Eocene as originally stated. The other genus in the family, Amplaster, contains three species: A. alatus (Argentina, Early Miocene-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 from the Early Pliocene of Venezuela, and Encope species from the Pliocene of Chile. The Abertellidae is represented 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 of southern Argentina. The early Late Miocene was the time when the máximum diversity of sand dollars was reached. The absence of Pliocene deposits along the southwestern coast of South America prevents us from knowing how these faunas changed during that period. Pleistocene fossils represent a modern fauna.