The jaws contained sharp teeth which were compressed laterally and unequal in size and shape, and this variation of tooth shape is known as heterodonty. The teeth on the premaxillae (bones at the very tip of the upper jaw) were slender, unlike those of the maxillae (the main tooth-bearing bones in the upper jaw) which had a straight posterior edge. The upper jaw bore 30 teeth, with each premaxilla carrying about 4 teeth and each maxilla 11, while the lower jaw held 22 teeth.