US state in whose Palaeocene beds teeth of Purgatorius were found, from soon after the Chicxulub impact.
Sources: The Journals of the Lewis and Clark Expedition
Sources: Ice Age Floods National Geologic Trail
Sources: Dinosaur census reveals abundant Tyrannosaurus and rare ontogenetic stages in the Upper Cretaceous Hell Creek Formation (Maastrichtian), Montana, USA
Sources: The Journals of the Lewis and Clark Expedition, Lewis & Clark National Historic Trail
Sources: Earliest Palaeocene purgatoriids and the initial radiation of stem primates