Climatic control of trace fossil distribution in the marine realm

Abstract

AbstractModern coastal and shoreface faunas exhibit strong latitude (climate) controlled distributions. In contrast, most ichnotaxa are long-ranging, and ichnofacies are widely distributed geographically. This is readily explained by the dominantly warmer and more equable climates of much of the past, as well as the diversity of the producers of most ichnotaxa. Nevertheless, in the Pleistocene, and in the Eocene, cool-water ichnofabrics can be recognized. The latitudinal distributions of thalassinidean crustaceans and infaunal spatangoid echinoids are examined because of their propensity to form distinctive and often abundant trace fossils. Three climatic zones are tentatively recognized from modern shore and shoreface sediments, and which are considered to extend back to the Mesozoic: tropical and subtropical with pellet-lined burrows (Ophiomorpha), echinoid burrows and other traces; temperate with echinoid burrows and mud-lined or non-lined thalassinidean burrows (Thalassinoides), but without Ophiomorpha; and arctic (cold waters) with only a molluscan and annelid trace fossil association. Examples demonstrating this climatic trend are drawn from the Cenozoic and Pleistocene.