Gargoyleosaurus is one of the earliest ankylosaurs known from reasonably complete fossil remains. Its total body length is an estimated 3 to 4 meters (9.8 to 13 ft). It may have weighed as much as 1 tonne. The holotype was discovered at the Bone Cabin Quarry West locality, in Albany County, Wyoming in exposures of the Upper Jurassic Morrison Formation.
The type species is G. parkpinorum