Meeting Abstract

P1.111  Saturday, Jan. 4 15:30  Functional constraint and convergent evolution of plagiaulacoid dentition in extant marsupials VANDER LINDEN, A.R. *; WILSON, G.P.; University of Washington, Seattle; University of Washington, Seattle avanderl@uw.edu

Distantly related taxa often have independently evolved the same or similar complex structure as a solution to common functional demands presented by their environment. One such example is the plagiaulacoid tooth—an unusual shearing blade that convergently evolved in four clades of extant and extinct mammals. Precisely how the function of the plagiaulacoid tooth and the tooth-bearer’s diet vary across these taxa is an open question. To test the association of plagiaulacoid tooth shape, diet, and function, I measured the surface complexity of lower cheek tooth rows of 13 species from five families of extant marsupials (Caenoelstidae, Burramyidae, Phalangeridae, Potoroidae, Macropodidae). I created three-dimensional digital elevation models from microCT scans of these specimens and used GIS software to generate orientation maps of the tooth surfaces. Contiguous pixels with the same orientation were grouped as a “patch” on the tooth surface, and the total number of patches (Orientation Patch Count, or OPC) approximates the number of shearing surfaces available to mechanically process food. Previous studies of placental mammals have shown that increases in tooth surface complexity as measured by OPC correlate with increased consumption of plant material. I found no correlation between OPC and diet in the marsupial taxa sampled. However, I did find that the surface complexity of the plagiaulacoid blade is negatively correlated with the surface complexity of the molars. Although broader taxonomic sampling is necessary to determine the pattern of tooth surface complexity and diet in marsupials, these results suggest a more nuanced and complex role for functional constraint in the convergent evolution of the plagiaulacoid dentition.