Species: siefkeri COLBERT, 1966
Etymology: In honor of Mr. Siefker, who first discovered the specimen.
Holotype: AMNH 2101
Locality: Former Belmont-Gurnee, or "Granton," Quarry immediately west of Tonnele Avenue and about opposite Hamilton Avenue, North Bergen County, New Jersey.
Horizon: Lockatong Formation, Newark Supergroup.
Age: Newark series, Late Carnian Stage, Late Triassic Epoch, Late Triassic.
Material: Skull missing premaxilla and some other parts of the skull, a complete skeleton lacking portion of tail, some ribs, left manus and lower lower segments of hind limbs.