Taphonomic overprinting on the late Palaeozoic terrestrial plant–animal interactions: a noise in the record

Abstract

Plant–animal interactions investigated largely in Glossopteris leaf fossils (1214 specimens) from the lower Permian strata of peninsular India reveal evidence of taphonomic modifications of the ichnofabric. The leaf fossils indicate both above-ground (pre-depositional) and on-ground (post-depositional) animal activities. Animal traces that extend beyond the margins of the leaf compressions or are emplaced on the leaf impressions are evidently post-depositional, preserved ex situ. Both feeding (herbivory/detritivory) and locomotary animal traces are interpreted in the host media. Preserved traces in the leaf fossils depict arrays of pre- and post-depositional events (viz., biotic interactions on green foliage, leaf detachment from the trees, post-mortem transport and burial) along taphonomic pathways. Accordingly, five taphonomic pathways are proposed based on varied combinations of pre- and post-depositional traces, emplaced on leaf fossils. Low diversity and persistent rarity of post-depositional traces (4%) as compared to more common pre-depositional traces (7%) in the sample population are noted. Less common post-depositional trace fossil assemblages of depauperate diversity indicate that stressed habitats prevailed at the depositional sites and a limited time window for preservation of plant–animal interactions. The recognition of pre- and post-depositional trace fossil suites ensures ichnological and ethological fidelity of faunal data on plant–animal interactions.