Latest Cretaceous eggshell assemblage from the Willow Creek Formation (upper Maastrichtian – lower Paleocene) of Alberta, Canada, reveals higher dinosaur diversity than represented by skeletal remains

The Willow Creek Formation (upper Maastrichtian – lower Paleocene) of southwestern Alberta is a poorly fossiliferous formation that preserves a low end-Cretaceous dinosaur diversity compared with most correlative terrestrial deposits in the North American Western Interior. Although only three dinosaur taxa are known from skeletal remains (Tyrannosaurus rex, Hadrosauridae indet., and Leptoceratopsidae indet.), study of hundreds of dinosaur eggshells recovered from several sites in the formation reveals the presence of a more diverse dinosaur assemblage. Morphological and histological analyses of the eggshells indicate the presence of at least seven dinosaur ootaxa (Continuoolithus, Montanoolithus, Porituberoolithus, Prismatoolithus spp., Spheroolithus spp.). These ootaxa are referable to at least two ornithopod and five small theropod species, likely including dromaeosaurids, oviraptorosaurs, and troodontids. When considering the taxonomic affinity of eggshells and skeletal remains, the present study tripl...