Author: Taylor, Compagno and Struhsaker, 1983
Diagnostic Features:
Trunk cylindrical and somewhat compressed, stout. Head very long, about length of trunk; snout extremely short, flattened and broadly rounded, not elongated and bladelike; eyes moderately large; mouth extremely large, terminal on head; gill openings moderately long, not cxtending onto dorsal surface of head, the last two over pectoral fin bases; unique gillrakers of fingerlike dermal papillae with cartilage cores fringing internal gill slits; teeth small, continuously varying and more or less awl-shaped, over 100 rows in either jaws, no anteriors, intermediate teeth or gaps in each upper dental band. First dorsal fin moderately large, semierect and angular; second dorsal less than half size of first but moderately large; pectoral fins large, narrow and elongated, much shorter than head in adults; pelvic fins moderate-sized, smaller than pectoral and first dorsal fins; anal fin smaller than second dorsal and with its base slightly behind second dorsal base, bases of both fins not pivotable; caudal fin not lunate, upper lobe long but less than half as long as rest of shark, lower lobe short but strong; precaudal pits present, caudal peduncle compressed and without lateral keels.
Remarks:
This new, highly distinct family is discussed in Taylor, Compagno and Struhsaker (1983).