Dr. Alex van Nievelt email Alex
Research Associate, Department of Biological Anthropology and Anatomy
Duke University Medical Center, Box 3170, Durham NC 27710
My research has centered around dental development in Monodelphis domestica . I have used a number of techniques to study tooth development, tooth eruption, tooth size, development of oral behaviors and body mass growth. Some of the more interesting findings include:
The upper first incisor is the last to erupt and does so as the young are weaned. This phenomenon has been observed in other polyprotodont marsupials. The reasonable (though not rigorously tested) explanation for this is that the gap between the upper second incisors provides a slot for the nipple which facilitates suckling.
Marsupials have eliminated tooth replacement in the anterior part of the mouth. It has been hypothesized that this is caused by the attachment to and constant presence of the nipple in the mouth early on in pouch life. Our data show that dental development is not generally suppressed early in pouch life. Furthermore, many placental mammals show similar reduced patterns of tooth replacement, obviously without having the marsupial suckling pattern. Interpretation of reproductive mode (i.e. marsupial vs. placental) based on evidence of tooth replacement pattern in fossil taxa is probably not justified.
The weaning period in M. domestica is associated with dramatic changes in growth rate, just preceded by an equally dramatic spike in the amount of dentition relative to body mass. During development, it appears that there is a complex interplay of development of feeding behaviors, tooth eruption and body growth and not a simple relationship of the size of the dentition and body mass.
- van Nievelt, A. F. H. and K. K. Smith. 2005. Tooth eruption in Monodelphis domestica and its significance for phylogeny and natural history. Journal of Mammalogy 86(2): 333-341. pdf file
- van Nievelt, A. F. H. and K. K. Smith. 2005. To replace or not to replace: The significance of reduced tooth replacement in marsupial and placental mammals. Paleobiology 31(2):324-346 (pdf file).
- van Nievelt, A. F. H. 2002. Dental development in Monodelphis domestica (Marsupialia: Didelphidae) and the evolution of tooth replacement in mammals. Ph.D. dissertation, Duke University , Durham , North Carolina .
- van Nievelt, A. F. H. and K. K. Smith. 1997. A case of bilateral 180° rotation of the last lower molars of Monodelphis domestica (Marsupialia: Didelphidae). Archives of Oral Biology 42 (8): 587-591.
- Smith, K. K. and A. F. H. van Nievelt. 1997. Technical comment: Comparative rates of development in Monodelphis and Didelphis . Science 275 : 683-684.