The fossil record as an archive of biological information in marine ice-scoured environments : Canadian Arctic Ocean

Post-mortem alteration of bivalve shells on arctic ice-scoured shelves helps illucidate the fidelity of death and fossil assemblages in these settings. Degradation rates and processes were constrained by (1) characterizing the taphonomic signature of death assemblages, (2) evaluating the live-dead fidelity of the benthos, and (3) net changes in experimentally deployed shells. Results revealed an extremely harsh taphonomic mill controlled by bioerosion, fragmentation and dissolution. Only select species accumulated in death assemblages, resulting in low taxonomic fidelity; at the habitat level 50% of the live species are found dead. 100% of the dead species are found alive, suggesting no temporal or spatial exotic contributions.Selectively preserved species could be time-averaged over 1 000s of years based on a preliminary model, yet high damage profiles suggest shorter scales of time-averaging. Skeletons are highly degraded compared to assemblages from temperate or tropical seas and reflect only a portion the living skeletonized community