The type species, G. erici was described in 1945 by Wilhelm Bock, who identified it as a coelurosaurian dinosaur related to Podokesaurus (at the time, "podokesaurids" were thought to be coelurosaurians). Its remains were found in the Upper Triassic Lockatong Formation of Montgomery County, eastern Pennsylvania, and the holotype includes skull fragments, several vertebra, ribs, gastralia, partial shoulder and hip bones, and several forelimb and hindlimb elements found in soft shale, while the paratype includes a femur and a tibia.
Wilhelm Bock described G. erici as a coelurosaurian dinosaur related to Podokesaurus (which was then classified as podokesaurids) in 1945. The remains were found in the Upper Triassic Lockatong Formation of Montgomery County, eastern Pennsylvania; the holotype includes skull fragments, vertebrae, ribs, gastralia, shoulder and hip bones, and forelimb and hindlimb elements from soft shale, while the paratype consists of a femur and tibia.