Probers

Abstract

Arthrophycid burrows are either made in sand or — if they penetrate into mud — backfilled with sand. The heterogeneous burrows assembled in this chapter are mainly found in muddy sediments, where they contrast in color: white in dark bituminous shales, dark in light-colored micritic marls and limestones. The reason is that they are actively backfilled with faecal material different from the host sediment. We speak of probers because the backfilled branches of a system are in most cases made head-on and blind-ended. The tendency to intensively use a given area, or volume, of sediment with a minimum of intersections suggests that the makers were primarily sediment feeders. In the cases of pronounced distancing between branches we may also consider chemosymbiotic animals that pumped hydrogen sulfide or methane from the pore water. A third possibility is a sanitary function. In reality, however, a burrow system may have served more than one of these functions.