Oysters from the Base of the Santa Cruz Formation (early Late Miocene) of Patagonia

MIGUEL GRIFFIN; ANA PARRAS

Early Miocene Paleobiology in Patagonia: High Latitude Paleocommunities of the Santa Cruz Formation

Cambridge University Press

Lugar: Cambridge; Año: 2012; p. 83 - 90

The Santa Cruz Formation has been traditionally considered a continental unit, and its contact with the underlying Monte León Formation as transitional. Invertebrates present in these transition beds, mainly mollusks, were used as an argument to refer them to the marine Monte León Formation. This was generally accepted, despite the shared lithological features of these beds and the overlying continental unit. Analysis of the fauna revealed that the only species actually living in the paleoenvironments in which these transition beds were deposited was Crassostrea oribgnyi (Ihering, 1897). This oyster belongs in a group adapted to inhabiting marginal marine settings, with hard or soft bottom and tolerating a wide range of salinity and subaereal exposure. The other members of the fauna are marine mollusks referable to taxa found in the underlying Monte León Formation, i.e. “Superpatagonian”. This term should not be used to refer to these beds, which are better considered part of the Santa Cruz Formation