TOOTH ERUPTION SEQUENCES IN FOSSIL AND RECENT ARTIODACTYLA

The observed morphology of artiodactyl dentitions is quite variable and deserves consideration when making both ecological and phylogenetic inferences with regard to these taxa. Careful recording of the available fossil and recent dentitions has allowed us to characterize the deciduous tooth arrangement and morphology of nearly one-hundred artiodactyl taxa. The variability in deciduous artiodactyl premolars includes deep crenulations in some anthracothere taxa, accessory cuspules in cebochoeres, serrations in entelodonts, and the more typical cusp arrangement of diacodexids. However, all taxa observed share the derived 6-cusped dp4 morphology that appears to be consistent in all artiodactyls.

The timing and order of replacement of the deciduous dentition by the permanent dentition can also be inferred in many species. By looking at multiple dentitions of a similar species, a general dental eruption and replacement sequence may be reconstructed for individual taxa. Inferring the eruption sequence of multiple artiodactyl taxa allows us to better understand the life history of these groups. In addition, it allows us to recognize developmental characters that may be used in phylogenetic analysis and which may help shed light on the evolutionary transformations within Artiodactyla.