This region includes Africa south of the Sahara, Madagascar, and the southwest corner of Arabia. Its mammal fauna exhibits the greatest diversity of all the major regions and 13 out of 26 orders are present. One of these is endemic, Tubu-lidentata, with a single species, the aardvark. There are 52 families (18 endemic), and over 1,000 species (more than 90% endemic). Endemic families include Giraffidae, Hippo-potamidae, Chrysochloridae (golden moles), Tenrecidae (ten-recs), and Macroscelididae (elephant shrews).
Africa was once joined to the Oriental region so there are many elements in common. One order, Pholidota (pangolins or scaly anteaters) contains one genus (Manis) with four Ethiopian species and three in the Oriental region. There are also many families in common, but long periods of isolation have led to the development of unique genera, for example elephants, rhinos, monkeys, apes, hyenas, and cattle.
The region is noted for the impressive array of large herbivores that occur in large numbers on the savannas of central, eastern, and southern Africa. There are also seven endemic genera of Old World monkeys, and two out of the four genera of great apes (chimpanzees and gorillas). There is also a great diversity of rodents and viverrid carnivores (23 out 25 genera are endemic). There are some noteworthy absences from the region, such as deer (Cervidae) and bears (Ur-sidae).
The unique nature of Madagascar's mammal fauna is well known and results from its long isolation from the mainland of Africa that now lies more than 250 mi (420 km) away. Madagascar finally broke away from Africa during the Middle Tertiary period and only a few groups of mammals appear to have been present at that time, namely lemurs, insectivores, small carnivores, and rodents. In the absence of competitors and later immigration, these ancestral groups were able to radiate into diverse arrays of new species. The lemurs developed into three families (Lemuri-
dae, Indriidae, Daubentoniidae) containing nine genera and 38 species. The tenrecs provide an excellent example of adaptive radiation, the 27 extant species having a bewildering variety of forms and occupying a great diversity of niches. The early carnivores consisted only of mongooses and civets and both have evolved into distinctive forms. The four extant mongoose species form an endemic subfamily Galidiinae. The civets also show a remarkable development, with seven species belonging to seven separate genera in three subfamilies. There are ten endemic rodents and an endemic bat family (Myzopodidae) containing a single species. The other bats present were presumably able to fly to the island at a later stage. Almost equally striking is the absence of so many widespread African forms such as antelopes, zebras, larger carnivores, lagomorphs, and monkeys. At some point, the bushpig (Potamochoerus porcus) and a small species of hippopotamus (Hippopotamus lemerlei) reached the island; the bushpig survives but the hippo became extinct, probably in prehistoric times.
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