The suggested those groups exhibited a prognathous (protruding) jaw reminiscent of primitive man, and were therefore less developed than the rest of society.
The snout was also proportionately shorter, and the tooth row was not at all prognathous, the snout tip not protruding relative to the remainder of the tooth series.
The mouthparts, along with the rest of the head, can be articulated in at least three different positions: prognathous, opisthognathous, and hypognathous.
