Species: petraios SUES & OLSEN, 1993
Etymology: Greek, petraios, "of or belonging to a rock," from Greek, petra, "rock," also the etymological root for the first name of the discoverer of the holotype, Peter A. Kroehler.
Holotype: USNM 448631
Locality: USNM locality 39981 (Tomahawk Locality), 0.16 km (0.1 miles) east of the eastern branch of Little Tomahawk Creek along the northeastern side of Old Hundred Road (VA 652), near Midlothian, Chesterfield County, Lat 77°40'15”N, Long. 37°27'45”W, Hallsboro 7.5 Minute Quadrangle, Virginia.
Horizon: Tomahawk Member, Turkey Branch Formation, Newark Supergroup.
Age: Early to middle Carnian Stage, Early Late Triassic Epoch, Late Triassic.
Material: Incomplete right dentary with 9 teeth.