TAPHONOMIC LOSSES BECOME TAPHONOMIC GAINS - AN EXPERIMENTAL APPROACH USING THE ROCKY SHORE GASTROPOD, TEGULA-FUNEBRALIS

The gaps in the fossil record are not liabilities for paleontologists but rather assets for evolutionary and paleoecological studies. The fo ssil record of rocky shore invertebrates is deemed poor, resulting fro m the bias of a high energy (physical) environment. The poor fossil re cord of the Pleistocene rocky shore gastropod Tegula funebralis appear s to be no exception to this rule. However, field studies, including e xperimentally deployed shells in two habitats, reveal five important t aphonomic processes that affect the resultant fossil resource for thes e gastropods: (1) the predilection for Tegula shells by the intertidal hermit crab, Pagurus samuelis, affects the longevity of the shells, ( 2) hermit crab-occupied shells of Tegula have a distinct array of bion ts distinguishable from the living snail and empty, experimentally tet hered shells, (3) biont types on tethered shells differ between two ha bitats (mudflat and rocky intertidal), and are thus useful for paleoen vironmental determinations, (4) physical processes greatly affected in tact shell longevity of experimental shells at the rocky intertidal si te, whereas at the mudflat site, mistaken predation by durophagous cra bs was the most important agent of shell destruction, and (5) despite these taphonomic losses, the Pleistocene fossil record of Tegula retai ns a good record of the biological factors that affect its preservatio n, that of pagurid crustaceans and their gastropod shell-associated bi onts. Taphonomic losses when viewed from a hierarchy of shell users, t hen, are gains in biological information that indicate the level of co mplexity within the shell-using community, and this record is not comp letely lost in high energy regimes.