The distinctive-looking little mammals in the African family Macroscelididae are known as elephant shrews or (from the Swahili) sengis. Despite the name, elephant shrews are not closely related to shrews--in fact, they are members of the Afrotheria and therefore more closely related to elephants (Seiffert 2007 and references therein)!
Elephant shrews are the size of mice or rats, ranging in length from 100 to 300 mm and in weight from 25 to 700 g. They have large eyes and ears, slender limbs, and a long, bare tail. A long tubular snout protruding from a strongly tapered skull accounts for the name "elephant shrew". All living elephant shrew species are specialized invertebrate-feeders, often feeding on ants especially. The fine-boned "soft-furred elephant shrew" lineage (subfamily Macroscelidinae) and the more robust "giant elephant shrew" lineage (subfamily Rhynchocyoninae) apparently diverged at least 25 to 35 million years ago. The macroscelidines are superficial surface-gleaners of small invertebrates (and occasionally fruits and seeds) in shaded but dry environments; the rhynchocyanines (represented only by Rhynchocyon) are found in moister habitats. where they forage for invertebrates by actively turning over leaf litter. Elephant-shrew species that have been studied are all socially monogamous, an unusual trait among mammals. (Kingdon 1997; Smit et al. 2011 and references therein)
The long, powerful hindlegs of elephant shrews ("Macroscelididae" means "big thigh") allow them to make vertical leaps from a standing position and to sustain their rapid, bounding escape from potential predators. Elephant shrews are almost exclusively diurnal. Reliance on shelters or burrows varies among species, but the giant elephant shrews use dry leaf litter to construct multiple 1 m-wide leaf mound shelters which they pile over shallow body-sized scoops in the soil. These mounds, which are constructed in the early morning, are used mainly as night shelters and as nurseries for their offspring. (Kingdon 1997; Smit et al. 2011 and references therein)
The family Macroscelididae as typically treated includes four genera and 17 species. The genera Macroscelides and Petrodromus are monotypic (i.e., each includes just a single species, the former a southwestern African gravel plain specialist and the latter having a southern, eastern, and central African distribution characterized by a wide habitat tolerance). Rhynchocyon includes four forest species found in eastern and central Africa (including one, R. udzungwensis, discovered only in 2005 and formally described by Rovero et al. in 2008) and Elephantulus includes 11 species with a range of habitat associations (including one, E. pilicaudus, that was formally recognized as distinct from E. edwardii, by Smit et al., only in 2008). Of all the elephant shrews, only E. rozeti occurs north of the Sahara (Smit et al. 2011). Recent investigations have supported the earlier suggestion that Elephantulus, as currently described, is not monophyletic (i.e., this group does not include all the descendants of the shared ancestor) and that there are grounds for subsuming Petrodromus and Macroscelides in Elephantulus (Douady et al. 2003; Smit et al. 2011).
- Seiffert, E. 2007. A new estimate of afrotherian phylogeny based on simultaneous analysis of genomic, morphological, and fossil evidence. BMC Evolutionary Biology 7: 13.
- Douady, C.J., F. Catzeflis, J. Raman, M.S. Springer, and M.J. Stanhope. 200). The Sahara as a vicariant agent, and the role of Miocene climatic events, in the diversification of the mammalian order Macroscelidea (elephant shrews). Proceedings of the National Academy of Sciences (U.S.A.) 100: 8325–8330.
- Kingdon, J. 1997. The Kingdon Field Guide to African Mammals. Academic Press, San Diego.
- Rovero, F., G. B. Rathbun, A. Perkin, T. Jones, D. O. Ribble, C. Leonard, R. R. Mwakisoma, and N. Doggart. 2008. A new species of giant sengi or elephant-shrew (genus Rhynchocyon) highlights the exceptional biodiversity of the Udzungwa Mountains of Tanzania. Journal of Zoology 274: 126-133.
- Smit, H.A., B.J. van Vuuren, P.C.M. O'Brien, M. Ferguson-Smith, F. Yang, and T.J. Robinson. 2011. Phylogenetic relationships of elephant-shrews (Afrotheria, Macroscelididae). Journal of Zoology 284: 133-143.
- Smit, H.A., T.J. Robinson, J. Watson, and B.J. van Vuuren. 2008. A new species of elephant-shrew (Afrotheria: Macroselidea: Elephantulus) from South Africa. Journal of Mammalogy 89 (5): 1257–1269.
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