Mr. Sanchez-villagra, Ontogenetic and phylogenetic transformations of the vomeronasal complex and nasal floor elements in marsupial mammals, ZOOL J LINN, 131(4), 2001, pp. 459-479
Histological sections and three-dimensional reconstructions of section-seri
es were used to document the anatomy of the vomeronasal complex and other a
spects of the ethmoidal region in representatives of 13 families and six or
ders of marsupial mammals, including for the first time Microbiotheria. The
changes during growth of several features were examined in ontogenetic ser
ies. Marsupials are very conservative in comparison with eutherians regardi
ng the vomeronasal complex. All have a vomeronasal organ and a nasopalatine
duct, have no nasopalatine duct cartilage, have no (or just an incipient)
palatine cartilage, and the overall construction of the nasal floor is unif
orm across species. Most features examined show a high degree of homoplasy
(e.g. presence of glandular ridges, isolated dorsal process of the parasept
al cartilage), and their systematic value is confined to low taxonomic leve
ls. Significant ontogenetic changes occur in features usually discussed in
the systematic/taxonomic literature. Amongst the didelphids examined, Calur
omys philander shows several autapomorphies. It is hypothesized that the op
ening of the VNO into the upper end of the nasopalatine duct was present in
the marsupial groundplan. Most marsupials have a large and horizontal ante
rior transverse lamina, the plesiomorphic condition, which becomes oblique
in diprotodontians. Some features are autapomorphies of well-supported mono
phyletic groups of marsupials, e.g. the conspicuous internasal communicatio
n of perameliformes and the 'tube-like' or ring-shaped paraseptal cartilage
of vombatiformes. An outer bar joining the middle (and not the dorsal-most
portion) of the paraseptal cartilage characterizes Australasian marsupials
and Dromiciops, with the exclusion of perameliformes, and evolved independ
ently in Caluromys philander. (C) 2001 The Linnean Society of London.