The rostral scale is projecting, upturned, recurved and keeled dorsally. The crowded, stiff, narrow leaflets are long and have strongly recurved or revolute edges. Thresher sharks are fairly slender, with small dorsal fins and large, recurved pectoral fins. The teeth are large, recurved, and serrated. The first is the Permian pteridosperm "Glossopteris", which already bore recurved leaves resembling carpels. The teeth are recurved and have serrations at the front and rear edges. The proboscis contains longitudinal rows of 18 recurved hooks each. The lower incisors were broad, recurved, and placed in a straight line across. Lastly, the unguals are recurved, exceptionally large, and strongly compressed laterally. The teeth of "Proterosuchus" were recurved, labiolingually compressed, and serrated, as in most archosauriforms. Fish-eating species have long and slender tooth crowns that are slightly recurved. The hands were unusually elongated, bearing sickle-shaped claws even more recurved than those of spinosaurids. They often have extendable, hinged jaws with recurved teeth. They often have extensible, hinged jaws with recurved teeth. The feet have strongly recurved claws to grip onto bark or other surfaces.