Dinosaurs, dung beetles, and conifers: Participants in a Cretaceous food web

Late Cretaceous trace fossils from the Two Medicine Formation of Montana are interpreted as herbivorous dinosaur feces reworked by scarabaeine dung beetles. These irregular blocks of comminuted plant material occur in isolated patches in fluvial flood plain sediments near dinosaur bone beds and nesting grounds. Numerous burrows in and around the specimens indicate significant invertebrate activity which suggests intense competition for a rich food resource. Some of the burrows are backfilled with organic matter that had been. translocated from the organic mass (during pat) into the adjacent sediment. Paracoprid dung beetles are the only extant organisms known to make similar caches. These unique ichnofossils provide evidence for commensal interactions between dung beetles, herbivorous dinosaurs, and conifers. This find also reveals a pathway through which fecal resources were recycled and suggests that scarabs evolved coprophagy through association with dinosaurs.