Fish taphonomy and environmental inference in paleolimnology

Abstract

The contribution of fish studies to palaeoecology generally takes the form of (1) inference from analogies in modern fish faunas and (2) fish taphonomy—the pattern of death and dispersal of bones. (1) Modern fish faunas and associated organisms provide taxonomic, ecological, or functional analogues for interpretation of ancient limiting factors and behaviors. These inferences presume taxonomic conservatism. They also presume functional relationships between morphological form and feeding mode or habitat. They become weak with increased geologic age or phyletic distance between ancient subject and modern anaogue. (2) Fish taphonomy may contribute information about limnology, community composition, life history, mortality, depositional environment, and preservation. Taphonomic reconstruction of ecology and preservation depends on the applicability of analogous processes in modern ecology and l limnology. In aquatic taphonomy, temperature is the most important factor in determining the fate of a carcass. Above about 16°C (depending on depth and pressure), most carcasses are made buoyant by bacterial decay gases and are transported to the surface where they may decay further and fall piecemeal into deepwater environments, or drift to beach environments where wave energy disarticulates, abrades, and scatters the bones. Below about 16°C, most carcasses remain on the bottom until buried; they may be disturbed by scavengers, depending on oxygen concentration in the hypolimnion.