Phylogeny: The elephant-shrews within the system of mammals
Elephant-shrews
are a phylogenetic old group and therefore are placed today in an own order
of mammals. This was not always so. For a long time there was disagreement
about their systematic relationship, which becomes evident by the fact,
that elephant-shrews were associated with various other groups. So they
were described as marsupials (Marsupialia), relates of ungulates (Ungulata)
and as hyraxes (Hyracoidea).
In most cases elephant-shrews were associated, together with the tree shrews (Scandentia), with the insectivores (Insectivora). In 1866 ERNST HAECKEL comprised tree and elephant-shrews because of having a caecum as Menotyphla, and separated them from the other insectivores, the Lipotyphla. Further common characteristics in regard to brain and skull anatomy and life style were interpreted as evidence for a phylogenetic relation. One zoologist was that convinced, that he proposed to place the elephant-shrews - after the tree shrews - to the primates!
The relationship between elephant and tree shrews soon came to doubt. Both groups show similarities in behavior and anatomy to some degree, but it is in question if these analogies are the result of adaptation to similar environments (convergence) or not.
A
partly solution of this discussion offered P. M. BUTLER in 1956 by classifying
the elephant-shrews as an own order of mammals. This seems to be justified
because of their phylogentic early separation from the main line of the
eutheria and resulting specialisations.
But
the discussion among the systematic classification of elephant-shrews was
and still is not completed. Fossils led zoologists to see relationships
between elephant-shrews and lagomorphs (Lagomorpha). It seems impossible,
but latest results of DNA-sequences indicate a common phylogenetic origin
of hyraxes, manatees, elephants, aardvarks, golden moles and elephant-shrews
(M. S. SPRINGER et al. [1997]: Endemic African mammals shake the phylogenetic
tree. Nature [London] 388 [6637]. p. 61-64). However - at the sight of
these animals one might also remember the famous "snouters", which were
discovered first by HARALD STÜMPKE in 1961 and were brought to public
by his executor GEROLF STEINER (;-).
Taxonomy: Systematic classification of elephant-shrews
The order of elephant-shrews (Macroscelidea) consists of one family (Macroscelididae), two subfamilies (Rhynchocyoninae and Macroscelidinae), four genera and alltogether 15 species. In some literature more than 15 species are described, depending on the author whether he classifies some subspecies as species or not. This also indicates that the classification of elephant-shrews is not really clarified yet.
Short-eared elephant-shrews
were described first by SHAW in 1800, by the scientific name Sorex proboscideus.
In 1829 A. SMITH mentioned the genus Macroscelides. After LICHTENSTEIN
described this species with a new name (Rhinomys jaculus) in 1832,
the name M. proboscideus was first cited by W. L. SCLATER (1801),
R. I. POCOCK (1912) and ROBERTS (1929).