Its skull was relatively small, on average about 37 centimeters long, 18 centimeters wide, and 15 centimeters high. The braincase was very firmly fused with the skull roof and palate. It had slender, forked premaxillae that turned up and expanded in the front, creating a shovel-like structure. "Desmatosuchus" is unique among aetosaurs in that its species are the only known aetosaurs that lacked teeth on their premaxillae. Their premaxillae fit loosely together with their maxillae, indicating flexibility at that joint. Their maxilla contained 10 to 12 teeth. "Desmatosuchus" also had very thin vomers, which bounded the medial side of the internal nares. These internal nares were relatively large, roughly half the length of the entire palate. The lower jaw typically carried 5 or 6 teeth, and had a toothless beak on the end. The dentary was about half the length of the lower jaw, with the front portion being toothless and covered by a horny sheath. Behind the dentary was a moderately large mandibular fenestra.