THE DIET OF OSTRICH DINOSAURS (THEROPODA: ORNITHOMIMOSAURIA)

Abstract:  The diets of ornithomimosaurian dinosaurs (Theropoda: Ornithomimosauria) have proved to be contentious owing to a dearth of unambiguous evidence in support of carnivory, omnivory or herbivory. Re-assessment of anatomical, taphonomical and palaeoecological evidence, and estimates of daily minimal energy budgets for two derived ornithomimosaurian genera, indicate that suspension-feeding and carnivory were unlikely. The combined presence of a keratinized rhamphotheca and gastric mill is strongly indicative of a herbivorous habitus for these dinosaurs. Herbivorous and omnivorous forms are rare among the non-avian Theropoda, but are more common than previously suspected. Rejection of carnivorous habits for derived ornithomimosaurs redresses apparent discrepancies in the relative abundances of the herbivore and carnivore guilds of several Late Cretaceous faunas.