New ichnofossil discovery in Mallorcan caves: Linking ancient and moden bat-ectoparasites coporolites.

Abstract

Bat ectoparasitic ichnofossils can be useful to elucidate microbial mediation in mineralization processes of organic material, supplying valuable information on ancient parasitology and palaeoecology, among other topics. Rod-shaped features found in Cova des Pas de Vallgornera (Mallorca, Spain) are described for the first time. They are related to an ancient bat colony inhabiting the cave in the Early Pleistocene. These micro-morphologies are cylindrical in shape with sizes of a few hundred microns in length and less than one hundred microns in diameter. They are composed by a mash of microscopic calcite particles of different sizes and shapes, lying on deposits that contain phosphates and clay minerals. Some of these rod-shaped morphologies are covered in microscopic crystals, whose mineralogy is composed mainly of calcite, associated with dolomite, quartz and clays, These deposits are interpreted as fecal droplets of bat ectoparasites (probably Nycteribiidae), that infested an ancient bat colony living in the cave before the collapse blocking of its natural entrances; from 2.4 Ma to present, the cave has remained sealed, preserving these deposits as a new ichnofossil related to invertebrate's coprolites. The observation of similar micro-structures in Cova de sa Guitarreta, another Mallorcan cave nowadays used for breeding by bats, allowed to study a present-day analogue; in this case, the rod-shaped structures are composed by organic detritus with lenticular concave forms (red blood cells?) and minute mineral particles. Therefore, these cylindrical features could be envisaged as excreta from bloodsucking bat flies, being represented by present-day deposits (Cova de sa Guitarreta) as well as fossil coprolites in the case of Cova des Pas de Vallgornera.