Superorder Squatinomorphii
Superorder comprising a single order (Squatiniformes), family (Squatinidae), and genus (Squatina). Medium in size (up to 2.5 m), the body is greatly flattened and expanded laterally. The snout is broad and short. The pectoral fins are expanded anteriorly in front of the gill slits to form triangular lobes, but are separate from the side of the head; the pelvic fins are laterally expanded and winglike. The tail is stout and only moderately depressed, with a longitudinal ridge at the level of the caudal peduncle. The two dorsal fins are not preceded by spines; an anal fin is lacking; the caudal fin is well developed, with the lower lobe larger than the upper lobe and the axis slightly arched ventrally (hypocercal). The eyes and spiracles are dorsally located, and the spiracles lack valves. The nostrils are separate from the mouth, with barbels on the anterior margin. The mouth is terminal, with well-developed labial folds, protrusible at the corners but not medially; the teeth are numerous, with a single sharp cusp and a broad base. There are five ventrolateral gill slits, partially covered by the anterior lobe of the pectoral fins. The upper surface of the body and tail is covered with denticles; generally a single middorsal row of thorns runs along the trunk and tail. The rostrum is short and trough-shaped. Antorbital cartilages are lacking; the nasal capsules are small and depressed; the postorbital wall is complete. The jaws are very long, with labial cartilages. The propterygia of the pectoral girdle are well developed and oriented anteriorly, the mesopterygia are enlarged, and the pectoral girdle does not articulate with the vertebral column; the vertebral column does not form a long fused tube (synarcual). There are 10-12 species; all are benthic on continental shelves in tropical and warm temperate waters; however, they are absent from the islands of the western Pacific. Swimming is accomplished by a sculling action of the tail. Their food consists of fishes, crustaceans, and mollusks. Larval development is viviparous, without a placentalike connection between female and young. The number of young within a female vary from 13 to 35.