Fossil egg and eggshells from the Upper Cretaceous Hell Creek Formation, Montana

Despite over a hundred years of intense paleontological exploration, the terrestrial rocks of the Upper Cretaceous (Maastrichtian) Hell Creek Formation of eastern Montana are remarkable for the absence of fossil eggs. Here, we describe the first fossil egg and additional eggshell fragments from the formation. The two-layered structure of the smooth 1600-µm-thick eggshell of Belonoolithus garbani, oogen. et oosp. nov., permits assignment of the 6...