 "Calyptosuchus" was named by Long and Ballew (1985) on the basis of UMMP 13950, an partial carapace with a vertebral column and pelvis that had been discovered in the Tecovas Formation of western Texas in 1931 by Ermin Cowles Case, who only went as far to assign the specimen to Phytosauria in a 1932 paper.Although publications in the 1990s and early 2000s treated the genus as a junior synonym of "Stagonolepis", recent work has found it generically distinct from "Stagonolepis" proper.This is because more material from the same species has been discovered, including a dentary bone, a possible maxilla, and further vertebrae from the neck and trunk.