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 to 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, Prismatoolithusspp., 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, indicative of arid to semi-arid conditions, typical of the formation were likely conducive to the preservation of calcareous eggshells.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Petrographic Characterization of Raw Material Sources at Oldupai Gorge, Tanzania

Oldupai Gorge is located within the Ngorongoro Conservation Area, a UNESCO World Heritage Site in northern Tanzania along the western margin of the East African Rift System. Oldupai’s sedimentary record exhibits a complex sequence of inter-stratified lithic assemblages associated with the Early, Middle, and Later Stone Age. While diachronic technological change is perceptible, the totality of locally available rocks remained largely unchanged through time. Here, thin section petrography, Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy, and Electron Probe Micro Analysis were employed to characterize source lithologies in the Oldupai region. One of our goals was to determine if outcrops have rock types with unique mineral compositions amenable for sourcing lithic artifacts. Geological samples were collected in primary and secondary positions, from which sixty-two samples were selected for analysis. Comparative analyses show that five outcrops have quartzites with unique mineral compositions, seven meta-granite varieties are unique to five individual outcrops, Engelosin phonolite samples are texturally and mineralogically unique, and magmatic samples recovered in secondary position may be sourced to their volcanic center. Our results demonstrate it is feasible to differentiate between source materials using optical mineralogy which implies that sourcing lithic artifacts based on mineral compositions is possible. This is further substantiated by assigning the source/s for previously described fuchsitic quartzite artifacts from three archaeological sites at Oldupai as this raw material type uniquely occurs at two nearby outcrops. Systematic archaeological testing will allow future researchers to glean new understandings of hominin behavior and resource procurement within the Oldupai paleobasin

Supplementary Tables S1 - S5 and Figure S1 from Incubation behaviours of oviraptorosaur dinosaurs in relation to body size

Table S1: Mid- to Upper Cretaceous oviraptorosaur egg and clutch specimens examined in this study; Table S2: Results of regression analyses for clutch volume (mm3, in logarithmic scale) against adult body mass (kg, in logarithmic scale) in living crocodylian and precocial bird species (n = 180) in order to predict adult body mass for the elongatoolithid specimens; Table S3: Outer and inner clutch diameters of various oviraptorosaur egg taxa; Table S4: Eggshell thickness of various oviraptorosaur egg taxa; Table S5: Eggshell porosity and predicted nest type in various oviraptorosaur egg taxa; Figure S1. Comparisons of egg shape in oviraptorosaurs