Zelenitsky, Darla KarenTherrien, FrancoisTanaka, KoheiKobayashi, YoshitsuguDeBuhr, Christopher Leonard2023-10-102023-10-102017-02-16Zelenitsky, D. K., Therrien, F., Tanaka, K., Kobayashi, Y., & DeBuhr, C. L. (2017). Dinosaur eggshells from the Santonian Milk River Formation of Alberta, Canada. Cretaceous Research, 74, 181–187. https://doi.org/10.1016/j.cretres.2017.02.016https://hdl.handle.net/1880/117365https://doi.org/10.11575/PRISM/42208The North American fossil record of dinosaur eggshells for the Cretaceous is primarily restricted to formations of the middle (Albian–Cenomanian) and uppermost (Campanian–Maastrichtian) stages, with a large gap in the record for intermediate stages. Here we describe a dinosaur eggshell assemblage from a formation that represents an intermediate and poorly fossiliferous stage of the Upper Cretaceous, the Santonian Milk River Formation of southern Alberta, Canada. The Milk River eggshell assemblage contains five eggshell taxa: Continuoolithus, Porituberoolithus, Prismatoolithus, Spheroolithus, and Triprismatoolithus. These ootaxa are most similar to those reported from younger Campanian–Maastrichtian formations of the northern Western Interior than they are to ootaxa reported from older middle Cretaceous formations (i.e., predominantly Macroelongatoolithus). Characteristics of the Milk River ootaxa indicate that they are ascribable to at least one ornithopod and four small theropod species. The taxonomic affinity of the eggshell assemblage is consistent with the dinosaur fauna known based on isolated teeth and fragmentary skeletal remains from the formation, although most ornithischians and large theropods are not represented by eggshell. Relative to the Milk River Formation eggshell, similar oospecies occurring in younger Cretaceous deposits tend to be somewhat thicker, which may reflect an increase in body size of various dinosaur lineages during the Late Cretaceous.enUnless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.dinosaursAlbertaeggshellsMilk River FormationtheropodSantonianArticleRGPIN/327513https://doi.org/10.1016/j.cretres.2017.02.016