The record of dinosaurs over the last 10 m.y. of the Cretaceous, as well as surrounding the Cretaceous-Paleogene boundary, helps to define extinction scenarios. Although Late Cretaceous dinosaur fossils occur on all present-day continents, only in North America do we find a terrestrial vertebrate fossil record spanning the Cretaceous-Paleogene boundary, although promising work may yield comparable records in South America, India, China, and Europe. For the present then, the North American record represents the proxy for our knowledge of dinosaur extinction. Over the last 10 m.y. of the Cretaceous (late Campanian to late Maastrichtian) in the northern part of the...