DOCUMENTING POSSIBILITIES OF REGIONAL VARIATION IN THE COLUMBIAN MAMMOTH (MAMMUTHUS COLUMBI) USING MORPHOMETRIC ANALYSIS OF CRANIAL AND DENTAL METRICS FROM SPECIMENS ACROSS THE UNITED STATES

Cranial morphometrics of the Columbian mammoth (Mammuthus columbi) have never been extensively researched. Most morphometric data on proboscideans has been collected on the soft-parts of extant animals. Paleontologically, these methods are not applicable when dealing with skeletal material. This study analyzes up to thirty unique, linear, cranial metrics from each specimen dependent on its orientation. Historically, the most accessible of mammoth metrics involve only the mandible of the animal. However, by utilizing the maxillary teeth as well as the cranium, regional variation of the species can be examined using various statistical methods. Previous studies of many other mammalian species demonstrate some form of regional variation, but this has never been studied in extinct proboscideans due to the difficulty in collecting data from mammoth crania. The Columbian mammoth is the largest of the mammoth species and demonstrates widespread distribution across the United States. As such, their extensive range allows for unique adaptations amongst smaller populations. Possible drivers for this regionally influenced variation may be linked to evolutionary forces, migratory patterns, and/or ontogenetic adaptations of these animals. Preliminary research conducted on the collection of mammoth remains at the Mammoth Site in Hot Springs, South Dakota yields distinct linear trends in cranial metrics with age. Great disparity was found when the Mammoth Site population (all males mostly between the ages of 12-29) was compared to the Huntington Canyon mammoth (a 53-year old male from a different physiographic province). Additional mammoth cranial data has been collected from across the United States encompassing the geographic range of the species, as fossil preservation and collection has allowed. This analysis of regional variation will also be applied to the Pygmy mammoth (Mammuthus exilis)crania from the Channel Islands of California to document evidence of Foster’s Rule and regional adaptation of a pygmy species.