Hyraxes retain or have redeveloped a number of primitive mammalian characteristics; in particular, they have poorly developed
internal temperature regulation, for which they compensate by behavioural
thermoregulation, such as huddling together and basking in the sun. Unlike most other browsing and grazing animals, they do not use the
incisors at the front of the jaw for slicing off leaves and grass; rather, they use the
molar teeth at the side of the jaw. The two upper incisors are large and tusk-like, and grow continuously through life, similar to those of rodents. The four lower incisors are deeply grooved "comb teeth". A
diastema occurs between the incisors and the cheek teeth. The permanent
dental formula for hyraxes is although sometimes stated as because the
deciduous canine teeth are occasionally retained into early adulthood. Their mandibular motions are similar to chewing
cud, but the hyrax is physically incapable of
regurgitation as in the
even-toed ungulates and some of the
macropods. This chewing behaviour may be a form of
agonistic behaviour when the animal feels threatened. The hyrax does not construct dens, but rather seeks shelter in existing holes of varying size and configuration. Hyraxes urinate in a designated, communal area. The viscous urine quickly dries and, over generations, accretes to form massive middens. These structures can date back thousands of years. The petrified urine itself is known as
hyraceum and serves as a record of the environment, as well as being used medicinally and in perfumes. Hyraxes inhabit rocky terrain across
sub-Saharan Africa and the Middle East. Their feet have rubbery pads with numerous sweat glands, which may help the animal maintain its grip when quickly moving up steep, rocky surfaces. Hyraxes have stumpy toes with hoof-like nails; four toes are on each front foot and three are on each back foot. They also have efficient
kidneys, retaining water so that they can better survive in arid environments. Female hyraxes give birth to up to four young after a
gestation period of seven to eight months, depending on the species. The young are
weaned at 1–5 months of age, and reach sexual maturity at 16–17 months. Hyraxes live in small family groups, with a single male that aggressively defends the territory from rivals. Where living space is abundant, the male may have sole access to multiple groups of females, each with its own range. The remaining males live solitary lives, often on the periphery of areas controlled by larger males, and mate only with younger females. Hyraxes have highly charged
myoglobin, which has been inferred to reflect an aquatic ancestry.
Similarities with Proboscidea and Sirenia Hyraxes share several unusual characteristics with mammalian orders
Proboscidea (elephants and their extinct relatives) and
Sirenia (
manatees and
dugongs), which have resulted in their all being placed in the taxon
Paenungulata. Male hyraxes lack a
scrotum and their
testicles remain tucked up in their abdominal cavity next to the kidneys, as do those of elephants, manatees, and dugongs. Female hyraxes have a pair of
teats near their armpits (
axilla), as well as four teats in their
groin (inguinal area); elephants have a pair of teats near their axillae, and dugongs and manatees have a pair of teats, one located close to each of the front flippers. The
tusks of hyraxes develop from the
incisor teeth as do the tusks of elephants; most mammalian tusks develop from the
canines. Hyraxes, like elephants, have flattened
nails on the tips of their digits, rather than the curved, elongated
claws usually seen on mammals. ==Evolution==