Abstract:  Herbivorous mammals are characterized by their ability to use microorganisms to digest cellulose.  To achieve this they must first be able to break down plant material efficiently, using their molar teeth.  This in turn requires precise neural control of jaw movements. The mechanics of mastication and neural control of jaw movements have been well documented in placental mammals (goats, horses etc.), but virtually nothing has been published on marsupial (kangaroos, wombats etc.) mastication. The two major groups of herbivorous mammals, marsupials and placentals, evolved independently from a common small insectivorous ancestor over 60 million years ago. Most likely this has led to the tacit assumption that  marsupials and placentals herbivores share the same patterns of control over jaw movements. However, in the work to be discussed in this paper marsupials exhibited mechanics and differential activity of the muscles controlling mastication that were unique and totally different from that of placental herbivores. Evolutionary steps that have resulted in two different strategies for the mechanical breakdown of vegetation will be discussed.  The unique characteristics of marsupial mastication appear to be related to the retention of a primitive feature: the inflected angle of the mandible. This feature has incidentally placed a constraint on the diversity of marsupial herbivores. Modification of this feature appears to be central to the greater diversity of placental herbivores.

Resume:  Prof. Fuzz Crompton was educated in South Africa.  He obtained his Ph.D. in 1953 from the University of Cambridge, England.  Prof.  Cromptom has held many positons.  Currently he holds the position of Fisher Research Professor of Natural History, Harvard University.