 Kritosaurus was discovered in the De @-@ na @-@ zin Member of the Kirtland Formation . This formation dates from the late Campanian stages of the Late Cretaceous Period ( 74 to 70 million years ago ) , and is also the source of several other dinosaurs , like Alamosaurus , a species of Parasaurolophus , Pentaceratops , Nodocephalosaurus , Saurornitholestes , and Bistahieversor . The Kirtland Formation is interpreted as river floodplains appearing after a retreat of the Western Interior Seaway . Conifers were the dominant plants , and chasmosaurine horned dinosaurs appear to have been more common than hadrosaurids . The presence of Parasaurolophus and Kritosaurus in northern latitude fossil sites may represent faunal exchange between otherwise distinct northern and southern biomes in Late Cretaceous North America . Both taxa are uncommon outside of the southern biome , where , along with Pentaceratops , they are predominate members of the fauna . 
