Backward-pointing serrations line the mandibles. The skull had a narrow snout filled with straight conical teeth that lacked serrations. The slide cocking serrations are also reduced in number on these later pistols. "Ichthyovenator"s teeth were conical, straight, and bore no serrations. The teeth bear prominent, apically oriented serrations. Stealth airframes sometimes display distinctive serrations on some exposed edges, such as the engine ports. These teeth were spoon-shaped with sharply pointed tips and serrations along their outer edge. Some shapes are designed for specific purposes such as sharpening scythes, drills or serrations. The beaks were robust and with small serrations. Tiger shark teeth are unique with very sharp, pronounced serrations and an unmistakable sideways-pointing tip. The teeth were compressed sideways and had serrations. The 48-52 teeth of the upper jaw are very thin and pointed, lacking serrations. Unlike most crocodilians, phytosaurs have tooth serrations. The serrations of "Dimetrodon" teeth were so fine that they resembled tiny cracks. Proof coins have 220 edge serrations, while bullion coins have 160.