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

Abstract

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 triples the known dinosaur diversity of the Willow Creek Formation, increasing the number of dinosaurs from three to at least nine species. Probable ornithopod eggshells comprise most of the eggshells preserved, although small theropods were likely an important component of the Willow Creek ecosystem as most ootaxa can be ascribed to these dinosaurs. Although fossil bones are rarely found in the Willow Creek Formation, fossil eggshells are common compared to most other dinosaur-bearing formations in Alberta. The caliche-bearing deposits,

Morphology and osteohistology of a large‐bodied caenagnathid (Theropoda, Oviraptorosauria) from the Hell Creek Formation (Montana): implications for size‐based classifications and growth reconstruction in theropods

“…Zelenitsky et al . 2017). Osteohistological descriptions of caenagnathids have been constrained to single limb bones in two taxa of caenagnathid, Gigantoraptor from the Early Cretaceous of China (Xu et al .…”

Paleoecological implications of two closely associated egg types from the Upper Cretaceous St. Mary River Formation, Montana

“…Although definitively identified ceratopsian eggs are unknown, the two layered structure of Tetonoolithus nelsoni rules out that the eggs belonged to this taxon or a hadrosaurine. Finally, T. nelsoni also differs from the eggs and eggshells reported from other Maastrichtian localities in the Western Interior of North America (Zelenitsky et al, 2017: Table 1). Whether the differences reflect taphonomic, ecological, or evolutionary factors requires additional specimens and further study.…”

Anomalous 13C enrichment in Mesozoic vertebrate enamel reflects environmental conditions in a “vanished world” and not a unique dietary physiology

“…1D) and the distance between the Canal Creek bentonite and the top of the Comrey sandstone as exposed at the nearby McPheeter's Bonebed site (Chiba et al 2015). The interval containing the RDS locality is consistent with the more organic-rich, warm subtropical, relatively humid and wet, seasonally flooded coastal plain deposits of the uppermost Oldman Formation (Eberth and Hamblin 1993; Eberth 2005, 2015; Chiba et al 2015; Arbour and Evans 2017; Cullen et al 2020), and lacks the caliche nodules (among other features) that characterize the more inland and seasonally arid environments of the middle Oldman Formation (Mack and Jerzykiewicz 1989; Chiba et al 2015; Zelenitsky et al 2016). The upper Oldman Formation preserved in the Milk River/Manyberries region is equivalent to the middle Coal Ridge Member of the Judith River Formation in northern Montana (Freedman Fowler and Horner 2015; Arbour and Evans 2017), while also being time-equivalent to the lower Dinosaur Park Formation as exposed further north in Dinosaur Provincial Park (Eberth and Hamblin 1993; Cullen and Evans 2016).…”