Paleoichnology

    My research in paleoichnology began as a sophmore at Macalester College as an actualistic taphonomy project. I set-up a dermestid beetle colony and attempted to recreate the insect markings observed by Drs. Raymond Rogers and Eric Roberts in dinosaur bone from the Late Cretaceous of Madagascar and Utah. The hypothesis was that these traces were made by a necrophagus insect under stressed environmental conditions (both Late Cretaceous examples were derived from semi-arid environments with evidence for drought). This research led to a article recently published in the Journal of Paleontology in which we described two new ichnogenera and species, Cubiculum ornatus and Osteocallis mandibulus. We hypothesize that these were puparial chambers and feeding traces, respectively. Cubiculum ornatus are three-dimensional ellipsoidal hollows typically found in the spongy parts of the bone. Osteocallis mandibulus are wandering shallow paths on the cortical (compact) bone surfaces. Both traces exhibit concave grooves aligned perpendicular to the long axis of the trace. We interprete those features as mandible markings. Similar markings have been found on every continent except Australia and Antarctica from the Triasssic to Quaternary and usually with the same stressed conditions. We suggest these trace fossils may be used to support paleoenvironmental reconstructions.