Elephant shrew

. Elephant shrews are small, quadrupedal, insectivorous mammals. They have scaly tails, long snouts, and bear a superficial resemblance to shrews or rodents. They have long legs relative to their size, which are used to move from one place to another like rabbits. Elephant shrews use their flexible proboscises to search for food, with the length of the snout varying between species. They are one of the fastest small mammals, having been recorded to reach speeds of . They vary in size from about , from . One species of giant sengi, the grey-faced sengi, weighs about 700 g. Compared to other mammalian insectivores, sengis have relatively large brains. Their lifespans are about two and a half to four years in the wild. They have large canine teeth, and also high-crowned cheek teeth similar to those of ungulates. Their dental formula is G ==Behavior and ecology==

Although mostly diurnal and very active, they are difficult to trap and very seldom seen; elephant shrews are wary, well camouflaged, and adept at dashing away from threats. Several species make a series of cleared pathways through the undergrowth and spend their day patrolling them for insect life. If the animal is disturbed, the pathway provides an obstacle-free escape route. Elephant shrews are solitary animals, despite many species living in monogamous pairs. They share and defend their home territory, which is marked using their scent glands. Short-eared elephant shrews inhabit the dry steppes and stone deserts of southwestern Africa. They can even be found in the Namib Desert, one of the driest regions of the earth. Females drive away other females, while males try to ward off other males. Although they live in pairs, the partners do not care much for each other and their sole purpose of even associating with the opposite sex is for reproduction. Social behaviors are not very common and they even have separate nests. The one or two young are well developed at birth; they are able to run within a few hours. Female elephant shrews undergo a menstrual cycle similar to that of human females, making it one of the few nonprimate mammals to do so. Elephant shrews were used in the 1940s to study the human menstruation cycle. The elephant shrew mating period lasts for several days. After mating, the pair will return to their solitary habits. After a gestation period varying from 45 to 60 days, the female will bear litters of one to three young several times a year. The young are born relatively well developed, but remain in the nest for several days before venturing outside. The thermal characteristics of elephant shrews with similar body size, habitat and distribution are very close in most of the classifications. They can maintain homeothermy in different ambient temperatures where most of the species regulate their body temperature at 35 °C and neither become hyperthermic but they balance the heat offload by increasing the EWL (evaporative water loss). Feeding habits Elephant shrews mainly eat insects, spiders, centipedes, millipedes, and earthworms. While awake, as much as 80% of their time may be spent foraging. An elephant shrew uses its nose to find prey and uses its tongue to flick small food into its mouth, much like an anteater. Eating large prey can pose a challenge; an elephant shrew struggling with an earthworm must first pin its prey to the ground with a forefoot. Then, turning its head to one side, it chews pieces off with its cheek teeth, much like a dog chewing a bone. This is a sloppy process, and many small pieces of worm drop to the ground; these are simply flicked up with the tongue. Some elephant shrews also feed on small amounts of plant matter, especially new leaves, seeds, and small fruits. ==Evolution==

A number of fossil species are known, all from Africa. They were separate from the similar-appearing order Leptictida. A considerable diversification of macroscelids occurred in the Paleogene period. The earliest definitive member was Chambia from the early-middle Eocene of Tunisia. Some early macroscelids, such as Myohyrax, were so similar to hyraxes that they were initially included with that group, while others, such as Mylomygale, were relatively rodent-like. These unusual forms all died out by the Pleistocene. Although macroscelids were classified in the past with many groups, often on the basis of superficial characteristics, considerable morphological and molecular evidence places them within Afrotheria, at the base of Afroinsectivora. In terms of timing, the divergence between macroscelids and afrosoricidans is thought to have occurred roughly 57.5 million years (Ma) ago, in the late Paleocene, while the diversification of extant macroscelids apparently began when the Rhynchocyon lineage split off about 33 Ma ago, in the early Oligocene. Elephantulus is considered to have separated from Macroscelidini later in the Oligocene, about 28.5 Ma ago. ==Phylogeny==

, Macroscelides proboscideus, Basel Zoo , Petrodromus tetradactylus, Mozambique , Petrosaltator rozeti, Morocco The 20 species of elephant shrew are placed in six genera, three of which are monotypic: • ORDER MACROSCELIDEA • Western rock elephant shrew, E. rupestris • Genus Galegeeska • Somali elephant shrew, G. revoilii • Rufous elephant shrew, G. rufescens • Genus Macroscelides • Namib round-eared sengi, M. flavicaudatus • Etendeka round-eared sengi, M. micus • Round-eared elephant shrew, M. proboscideus • Genus Petrodromus • Four-toed elephant shrew, P. tetradactylus • Genus Petrosaltator • North African elephant shrew, P. rozeti • Genus Rhynchocyon • Golden-rumped sengi, R. chrysopygus • Rhynchocyon chrysopygus mandelai • Chequered sengi, R. cirnei • Rhynchocyon cirnei cirnei • Rhynchocyon cirnei shirensis • Rhynchocyon cirnei reichardi • Rhynchocyon cirnei hendersoni • Rhynchocyon cirnei macrurus • Black and rufous sengi, R. petersi • Rhynchocyon petersi petersi • Rhynchocyon petersi adersi • Stuhlmann's sengi, R. stuhlmanni • Grey-faced sengi, R. udzungwensis ==References==