Marine and terrestrial invertebrate borings and fungal damage in Paleogene fossil woods from Seymour Island, Antarctica

摘要

An assemblage of permineralized conifer and angiosperm woods collected from Paleogene marine strata on Seymour Island during the Swedish Antarctic expedition of 1901-1903 includes many specimens with internal damage caused by an array of xylophagous organisms. Short, broad, clavate borings referable toGastrochaenolites clavatusare attributed to pholadid bivalves. Elongate borings with carbonate linings referable toApectoichnus longissimuswere produced by teredinid bivalves. Slender, cylindrical tunnels cross-cutting growth rings and backfilled in meniscoid fashion by frass composed of angular tracheid fragments were probably produced by a terrestrial beetle borer. They are most similar to tunnels generated by modern cerambycid and ptinid coleopterans. Less regular, spindle-shaped cavities and degraded zones flanking growth rings are similar to fungi-generated modern white pocket rot. Larger chambers in the heartwood referable to the ichnotaxonAsthenopodichnium lignorumwere produced by an alternative mode of fungal degradation. The biological interactions evident in the fossil woods illustrate additional terrestrial trophic levels enhancing the known complexity of ecosystems on and around the Antarctic Peninsula shortly before the initial pulse of mid-Cenozoic glaciation in Antarctica that caused extirpation of the majority of plants and animals in that region.