Anatomy of the oro-nasal region of some species of Tenrecidae and considerations of Tupaiids and Lemurids.

The place of the tree shrews in the phylogeny and taxonomy of the eutherians has become a very controversial problem. The crux of this matter is our rather poor knowledge of the anatomy of the modern insectivores. More sufficient data on the morphology of the insectivores would facilitate a judgement about whether the modern tree shrews are possible extant representatives of a group which was ancestral to the primates. The oro-nasal region is a complex of anatomically heterogeneous structures which are in functional cooperation. Because of the anatomical heterogeneity and the various functions of the structures constituting the oro-nasal complex, the study of this area has already provided a few data which might be relevant to this problem. The extant insectivores are in any event a phylogenetically heterogeneous group which cannot be considered an evolutionary entity. They are surviving relics, of different phylogenetic ages, of an eutherian fauna which flourished in middle to late cretaceous times. Therefore we can expect to see very diverse anatomical characteristics within the insectivores, which impede the accurate classification of the tree shrews. In this study it is demonstrated that there are essential differences within the oro-nasal region of the Tenrecoidea although the material available for anatomical studies was limited. Most important is that Setifer and Echinops possess an unpaired ductus nasopalatinus communis, which originates from the fusion of the paired nasopalatine ducts. The papilla palatina is absent; the ductus nasopalatinus communis opens into the cavum oris through a median unpaired orifice. Taste buds are absent in that area.