Taphonomic Feedback in Miocene Assemblages: Testing the Role of Dead Hardparts in Benthic Communities

Abstract

The accumulation of dead hardparts can directly influence the structure and dynamics of benthic communities by changing the physical characteristics of the sea floor. Biotic changes driven by such liveldead interactions have recently been termed taphonomic feedback (TF) to stress a) the role of post-mortem processes in the availability of hardparts, and b) that not only does the life assemblage influence the death assemblage, but the accumulation of a death assemblage affects the living one. This paper presents a quantitative test for the operation of taphonomicfeedback in the fossil record. Assemblages from Miocene strata of Maryland exhibit a statistically significant correlation between the abundance of shell-gravel dwellers (including epifauna and infauna) and sediment shelliness consistent with faunal changes predicted by TF. Alternative explanations for the correlation, such as differential preservation potentials of soft-bottom and shell-gravel taxa, faunal response to changing water energy, and livellive interactions, can be rejected. The operation of TF has several implications for analysis of the fossil record: a) as a driving mechanism for faunal change in benthic communities; b) as an approach to reconstructing patterns in the accumulation (and non-accumulation) of hardparts and sediment; and c) as an indication of the apparently prolonged post-mortem persistence of skeletal material in some settings and the biologically and taphonomically complex origins of many densely fossiliferous deposits.