Ichnology of osteoderms of the pampathere Holmesina occidentalis from the Late Pleistocene / Early Holocene Tablazo Formation, Santa Elena Peninsula, Ecuador

Abstract

The first evidence of parasite-induced and scavenger-produced bioerosion is reported from large cingulates from the Late Pleistocene Coralito fauna on the Santa Elena Peninsula of Ecuador. These traces occur on the external surface of osteoderms from the large pampathere Holmesina occidentalis. Traces observed include shallow to deep amorphous etchings, shallow ovoid to hemispherical pits of various sizes (Karethraichnus lakkos) deep, cylindrical pits (K. kulindros), shallow, horizontal, gently sinuous, grooves, straight, horizontal, smooth-walled, u-shaped to rounded v-shaped grooves (Linichnus bromleyi) and triangular to subrounded puncture-marks (Nihilichnus nihilicus). Both shallow and deep ovoid to hemispherical pits are attributable to parasitic arthropods, most likely tungid fleas and ticks. The shallow and deep amorphous etchings likely record corrosion by dipteran secretions and bacterial infections. The meandering grooves may record the activity of dermestid beetle larvae. The straight grooves are interpreted to record a variety of tooth and claw scrape marks. Traces attributed in invertebrates are interpreted to record the activity of parasites, whereas the scratchmarks may have been emplaced postmortem, likely by scavengers rather than predators. Overall, parasite loads on Coralito H. occidentalis appear to have been light, with evidence of only minor scavenging of their carcasses after their death.