Chapter 5 - Afrotheria

Abstract

This superorder includes insectivores (aardvark, tenrecs, sengis, golden moles) and herbivores, of which hyraxes and elephants are terrestrial and sirenians aquatic. In many afrotherians the dentition is not fully erupted until after the attainment of sexual maturity. In elephants, the molars erupt into function one by one, while in manatees, supernumerary molars are formed continually, so that in both forms the ability to process plant material is maintained throughout life. Among the insectivores, the mainly termite- and ant-eating aardvark has peglike, hypselodont teeth that lack enamel, tenrecs and golden moles have zalambdodont molars, and sengis, which include some plant material in their diet, have quadrituberculate molars. Sirenians eat relatively soft plant foods. In dugongs, horny pads are used to shred vegetation, while in manatees the reduction of food is completed by grinding between the molars. Hyraxes have caniniform upper incisors and chisel-shaped lower incisors used, respectively, for defense and grooming. The upper molars possess raised buccal edges forming a continuous cutting blade, which works against the lower molars. Elephants possess tusks (enlarged hypselodont incisors) and grinding molars, which become larger as they succeed one another, eventually reaching an enormous size.