Survival of crinoid stalk fragments and its taphonomic implications

Paleontological evidence indicates that crinoids (sea lilies: Echinodermata) were a major constituent of Paleozoic and Mesozoic shallow-marine communities (Meyer and Macurda, 1977 ;Cain, 1968).In the fossil record crinoid stalks usually occur in much greater abundance than other body parts such as arms and calyces.This difference has been attributed to selective preservation, the result of post-mortem process of fossilization or taphonomy (Baumiller and Ausich, 1992 ;Moore and Jeffords, 1968).Our observation of living crinoids in aquaria demonstrates that stalk fragments detached and isolated from a living crinoid survive more than one year, whereas other body parts tend to disarticulate rapidly.Such long survival of stalk fragments of crinoids firstly explains the dominance of crinoid stalks over other body parts in the fossil record, and secondly, and more importantly, it strongly suggests that such detached fossil stalks, as well as stalk pieces observed on today's sea floor, continued living for a long time, and were not dead body parts as previously considered.