SPECIES DISCRIMINATION AND MORPHOLOGICAL RELATIONSHIPS OF KANGAROO RATS (DIPODOMYS) BASED ON THEIR DENTITION

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Abstract
Fossils of the Heteromyidae usually are distinguished using quantitative dental characters because of a lack of diagnostic qualitative characters. However, utility of these characters in addressing taxonomic questions is unclear. Teeth of 19 extant species of kangaroo rats (Dipodomys) were measured to determine if quantitative characters provided reliable separation of taxa and to what extent morphometric analyses revealed meaningful higher level relationships. A discriminant analysis correctly allocated >70% of specimens to their a priori species groups. Dimensions that were best able to separate taxa, as judged from a canonical variate analysis, were lengths of premolars and 1st lower molar. Squared Mahalanobis distances, canonical variate analysis, principal component analysis, cluster analysis, and minimum spanning trees supported morphological groupings including: D. nelsoni and D. spectabilis; D. compactus and D. ordii; D. merriami and D. nitratoides; and the 5 species D. agilis, D. heermanni, D. panamintinus, D. simulans, and D. stephensi. D. deserti and D. elator differed in their dental morphology from all other taxa. Overall, results closely paralleled those of previous workers, suggesting that quantitative dental characters can reliably distinguish heteromyid taxa and perhaps help elucidate higher level taxonomic relationships.