This specimen was found in Voyizane, Joe Gqabi District, Cape Province, in rocks of the upper Elliot Formation, a rock formation that dates to the early part of the Early Jurassic (Hettangian–Sinemurian, approximately 200 to 190 million years ago). It was collected during a 1966–1967 expedition but not formally named and described until 2012, when Paul Sereno, who had recognized it as unusual in the 1980s, published a description. The type species is P. africana.[2] Pegomastax differed from other heterodontosaurids by details of the skull. The lower jaw was robust, with a short beak. Like most other heterodontosaurids, Pegomastax had an enlarged canine-like tooth at the beginning of the lower jaw's tooth row, which may have had a defensive function.