Abstract

Occurrences of articulated, multi-element skeletons of edrioasteroids provide evidence of sudden burial and an opportunity for detailed paleoecologic analysis. This study examines two catastrophically buried communities of edrioasteroids from Florence, Kentucky and Sharonville, Ohio. In these two occurrences, the edrioasteroids Isorophus cincinnatiensis, Streptaster vorticellatus, and Carneyella pilea utilized brachiopod and mollusk shells as hard substrates for attachment. Age structure analysis for specimens of Isorophus cincinnatiensis on both pavements show right-skewed distributions that are attributed to high juvenile mortality. Thecae on the Florence pavement have slight bimodal preferential orientation, likely in response to current flow, whereas no preferential thecal orientation was noted for specimens on the Sharonville pavement. Spatial analysis of the Florence pavement indicates a clustered edrioasteroid distribution resulting from multiple edrioasteroids attached to single brachiopod shells. Edrioasteroid margin deformation, in response to inter- and intraspecific competition, provides evidence that edrioasteroids were unable to move once attached to the substrate. Spatial analysis for Isorophus cincinnatiensis on the Sharonville pavement shows few instances of multiple edrioasteroids attached to individual shells. Instead, this clustered distribution suggests enhanced encrustation in areas of enhanced survival (i.e., increased feeding opportunity). The high degree of thecal disarticulation on the Sharonville pavement suggests postmortem bloating and rupture.

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