SCLEROBIONTS ON PATAGONIAN OYSTERS FROM THE PUERTO MADRYN FORMATION (EARLY-LATE MIOCENE, ARGENTINA)

ROMERO, MARÍA; BREZINA, SOLEDAD; BREMEC, CLAUDIA; CASADÍO, SILVIO

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 2018 vol. 55 p. 179 - 196

0002-7014

This work describes the composition and distribution of sclerobionts on the Miocene Patagonian oyster Ostrea alvarezii d?Orbignyand provides information about its paleoenvironment. The structure of sclerobiont assemblages and their preferential distribution onleft/right valves (n=340) as well as their external/internal surfaces and areas was evaluated by means of multivariate analyses (nMDS,SIMPER), non-parametric tests for producing mean comparisons, and goodness of fit tests using coverage and abundance data. Sixteenichnotaxa were recorded. Bivalves, polychaetes and bryozoans were the most representative encrusters. External surfaces, left valves andsediment-free areas were the most colonized. O. alvarezii beds are interpreted as within-habitat time-averaged assemblages. Oystersappear to have lived in small subtidal channels in a low energy tidal flat and closely related to the sediment-water interface, with the rightvalve resting on the substrate. Sclerobionts showed diverse behaviors, trophic levels and tiering. This suggests that sclerobiont assemblageson O. alvarezii had a complex structure with subdivision of resources, including a vertical colonization of valves by tracemakers at differentlevels of depth