First study of continental bioerosion traces on vertebrate remains from the Cretaceous of Algeria

Abstract

Trace fossils, representing ichnospecies Cubiculum ornatus, C. inornatus, Cubiculum isp., and Cuniculichnus variabilis as well as three indeterminate morphological categories (thin branching grooves A and B, furrows and circular chambers), are here recorded on vertebrate remains from the mid-Cretaceous (lower Cenomanian) of the ‘Continental Intercalary’ deposits in the Gara Samani locality (central Sahara of Algeria). Apart from thin branching grooves (A and B), which are thought to result from root etching, the bioerosion traces recorded on the bones comprise circular chambers and furrows, which represent pupation chambers of scavenging insects, most likely attributed to dermestid beetles. These trace fossils are identified and described for the first time from the Cretaceous of Algeria. They add new data to the trace-fossil assemblages previously reported from other Cretaceous successions of North Africa (e.g., the Kem Kem beds in Morocco). Sedimentological clues indicate a braided fluvial system environment. Taphonomic analysis suggests that the vertebrate remains were most likely subaerially exposed for a prolonged time prior to being transported and finally buried. Therefore, most of the studied borings are likely the result of dermestid beetle larvae feeding on dry bones on dry lands; other borings represent plant etchings produced after the bones were partially covered by, or completely buried, in sediments.