Contrasting encrustation patterns on trigonioid and pectinid bivalves from the Early Cretaceous of the Neuquén Basin, Argentina

LUCI, LETICIA

Mendoza

Congreso; 4th International Palaeontological Congress; 2014

IPA-CONICET

Encrusting faunas provide exceptional opportunities for palaeoecological studies, since they preserve several key features, like absolute abundance and spatial relationships among individuals. The encrusting fauna of semiinfaunal trigonioids of the genus Steinmanella (lower Valanginian of the Mulichinco Formation and upper Valanginian-low Hauterivian of the Agrio Formation) were compared to the large epifaunal pectinid Prohinnites (upper Valanginian, Agrio Formation). Both inhabited shallow normal marine settings. All of their encrusters were mapped, recording their type, size and position. The percentage of shells colonized by at least one encruster was calculated for both basibionts, along with their species richness and Pielow´s Diversity Index. Mean of encrusters per valve were calculated and compared with an analysis of deviance. Each basibiont´s valves were divided in zones to assess the distribution of encrusters by a generalized linear mixed model (GLMM). Percentage of valves encrusted was significantly (p