Fossil teeth were found in Colorado, USA and Alberta, Canada. This theropod is known from an almost complete fossil found in the Djadokhta Formation, Ukhaa Tolgod, Mongolia. The members of a clade are closely related to each other. A clade is monophyletic . They show the distribution and origins of shared characteristics.
Cladograms are testable hypotheses of phylogenetic relationships.
It lived during the late Cretaceous period , about 80 to 75 million years ago. Claosaurus was named by paleontologist O. Marsh in 1890. The type species is C. agilis . In classification, a class is a group of related or similar organisms. A class contains one or more orders.