Rare assemblages of woody coprolites from different strata of the Two Medicine Formation provide surprising perspectives on the feeding behavior of Late Cretaceous ornithischian dinosaurs. Most of the irregularly shaped, calcareous specimens are largely composed of fragmented conifer wood (13%–85%) and can be identified as coprolites by the presence of distinctive backfilled dung beetle burrows. The large size (up to 7 L in volume), fibrous contents, and associated bones and eggshell strongly suggest that the source animals at one site were Maiasaura hadrosaurs. The wood-bearing coprolites occur in strata ranging in age from ∼74–80 Ma, revealing a recurring (possibly seasonal) habit of wood ingestion. The preponderance of wood in the specimens and the absence of recognizable small-diameter twig fragments suggest that wood ingestion was intentional—that the coprolite producers had not merely consumed wood inadvertently when feeding on the leaves and bark of terminal branches. Because undegraded wood provides inconsequential nutritive value for vertebrates, it is unlikely that ornithischians would have expended the energy to masticate intact wood for little benefit. Furthermore, patterns of tissue damage in the fecal wood fragments suggest fungal degradation. Thus, the most parsimonious explanation for the high fecal wood content is that the coprolite producers consumed decomposing wood to capitalize on resources released by fungal attack, along with the tissues of the decomposers and associated invertebrate detritivores. These multiple coprolite deposits provide direct fossil evidence of recurring dinosaur diets and suggest that some ornithischians at least occasionally tapped detrital resources. Although such feeding behavior is rare in large extant herbivores, utilization of rotting wood would have augmented the resource options of Cretaceous ecosystems that lacked fodder provided by grasses and other derived angiosperms.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.