Anatomie et valeur systématique de l’oreille moyenne des rongeurs actuels et fossiles

Abstract

A study of comparative anatomy of the middle ear of the order Rodentia was undertaken. Over 100 rodent genera were studied and compared with various mammals. The variation in the anatomy of the middle ear was analyzed to distinguish the plesiomorphous and apomorphous condition of each character in comparison with the pre-mammalian state and by use of comparative physiology. Results were used to construct a classification of the families and super-families of rodents, based solely on this region. This taxonomy was then compared to that previously established by cranial and dental studies. The primitive pattern is found in the following groups: Sciuravidae, Theridomorpha, living Zapodidae, Muridae and Cricetinae and the Oligocene genera, Pseudocricetodon, Eutypomys and Paradjidaumo. The Paramyinae and Eucricetodon show at least 1 advanced character and should no longer be considered either the most primitive rodents or the most primitive Myomorpha. The variability of the Phiomorpha overlaps that of the Caviomorpha. This similarity reinforces the previously known homologies of skull, dentition and cephalic arterial system and further enhances the validity of the regrouping Hystricognathi Lavocat (1973). The Aplodontidae are closer to the Sciuridae than to the Paramyidae. The Miocene Anomaluridae may be derived from Theridomorpha-like genera. The Castoridae and the present Geomyidae remain isolated. These results would appear to justify further studies of similar nature in other orders of mammals.