The Kirtlandian, a new land-vertebrate "age" for the Late Cretaceous of western North America
— Robert M. Sullivan and Spencer G. Lucas

The Kirtlandian is a new land-vertebrate “age” (LVA) representing 2.9 million years of Campanian time that fi lls a long-standing biochronologic gap between the Judithian and Edmontonian LVAs. This new LVA is characterized by the vertebrate fossil assemblages of the Fruitland and Kirtland formations, San Juan Basin, New Mexico, and the ceratopsine dinosaur Pentaceratops sternbergii is the principal index fossil. The Kirtlandian is defined as the time between the first appearance of Pentaceratops sternbergii (= end of the Judithian) and the first appearance of Pachyrhinosaurus canadensis (= beginning of the Edmontonian). Characteristic Kirtlandian vertebrates include: Melvius chauliodous, Denazinosuchus kirtlandicus, Kritosaurus navajovius, Anasazisaurus horneri, Naashoibitosaurus ostromi, Parasaurolophus tubicen, P. cyrtocristatus, Nodocephalosaurus kirtlandensis, and Prenocephale goodwini.