The oyster Crassostrea? hatcheri (Ortmann, 1897), a physical ecosystem engineer from the upper Oligocene-lower Miocene of Patagonia, southern Argentina.

PARRAS, ANA; CASADIO, SILVIO

PALAIOS

Allen Press

Lugar: Lawrence; Año: 2006 vol. 21 p. 168 - 186

0883-1351

The oyster Crassostrea? hatcheri (Ortmann) is one of the most common fossils in Oligocene–Miocene marine rocks in Patagonia, southern Argentina. This oyster is distinguished by its large size and the great thickness of its valves. It built framework reefs in shallow-shelf environments, and its valves formlarge biogenic and sedimentologic concentrations exposed in many areas of Patagonia. This paper focuses on the community of boring and encrusting organisms living on the valves of C.? hatcheri, in both the biogenic and sedimentologic concentrations. This community includes fungi, algae, sponges, arthropods, bryozoans, phoronids, polychaetes, brachiopods, and mollusks. The recorded diversity is comparable to that observed in Recent oyster reefs, suggesting that C.? hatcheri was a physical ecosystem engineer in shallow-shelf environments during the late Oligocene–early Miocene. Primary factors in their role as facilitating organisms were, besides the size of the valves, the age of adult specimens (average5 25 years), high population densities, wide geographical range (more than 108 latitude), and long temporal range (more than 5My), in addition to the framework of the reefs and the sedimentologic concentrations of the valves.Crassostrea? hatcheri (Ortmann) is one of the most common fossils in Oligocene–Miocene marine rocks in Patagonia, southern Argentina. This oyster is distinguished by its large size and the great thickness of its valves. It built framework reefs in shallow-shelf environments, and its valves formlarge biogenic and sedimentologic concentrations exposed in many areas of Patagonia. This paper focuses on the community of boring and encrusting organisms living on the valves of C.? hatcheri, in both the biogenic and sedimentologic concentrations. This community includes fungi, algae, sponges, arthropods, bryozoans, phoronids, polychaetes, brachiopods, and mollusks. The recorded diversity is comparable to that observed in Recent oyster reefs, suggesting that C.? hatcheri was a physical ecosystem engineer in shallow-shelf environments during the late Oligocene–early Miocene. Primary factors in their role as facilitating organisms were, besides the size of the valves, the age of adult specimens (average5 25 years), high population densities, wide geographical range (more than 108 latitude), and long temporal range (more than 5My), in addition to the framework of the reefs and the sedimentologic concentrations of the valves.C.? hatcheri, in both the biogenic and sedimentologic concentrations. This community includes fungi, algae, sponges, arthropods, bryozoans, phoronids, polychaetes, brachiopods, and mollusks. The recorded diversity is comparable to that observed in Recent oyster reefs, suggesting that C.? hatcheri was a physical ecosystem engineer in shallow-shelf environments during the late Oligocene–early Miocene. Primary factors in their role as facilitating organisms were, besides the size of the valves, the age of adult specimens (average5 25 years), high population densities, wide geographical range (more than 108 latitude), and long temporal range (more than 5My), in addition to the framework of the reefs and the sedimentologic concentrations of the valves.C.? hatcheri was a physical ecosystem engineer in shallow-shelf environments during the late Oligocene–early Miocene. Primary factors in their role as facilitating organisms were, besides the size of the valves, the age of adult specimens (average5 25 years), high population densities, wide geographical range (more than 108 latitude), and long temporal range (more than 5My), in addition to the framework of the reefs and the sedimentologic concentrations of the valves.5 25 years), high population densities, wide geographical range (more than 108 latitude), and long temporal range (more than 5My), in addition to the framework of the reefs and the sedimentologic concentrations of the valves.8 latitude), and long temporal range (more than 5My), in addition to the framework of the reefs and the sedimentologic concentrations of the valves.