OSTEOLOGY AND GEOLOGY OF THE AN ICE AGE FOSSIL FROM IDAHO: THE BELLOWS-FRUITLAND MAMMOTH

Mammoth fossils can provide information about a specific, individual animal as well as contribute to a greater understanding of anatomical variability in extinct populations. Geologic studies of the deposits containing the fossils can be used to infer local Pleistocene environmental conditions and taphonomic processes. In 2008 a set of fossil bones were found in a gravel pit near Fruitland, Idaho. They were discovered accidentally and consisted of a relatively complete mammoth skeleton. Analysis of the bones as part of an undergraduate research project documented the presence of a right femur, right tibia, right fibula, partial pelvis, right and left humeri, right and left radii and ulnae, vertebrae, rib fragments, tusks, stylohyoid, two mandible fragments (with molars), and one articulated foot (with tarsals, metatarsals, and phalanges). The number and arrangement of plates in the teeth are consistent with the species Mammuthus columbi (Columbian mammoth). Based on the length of the humerus, the approximate height was 3 m (8.5 feet) which could imply either a juvenile or small adult female. Since the amount of wear on the teeth suggests an adult, it might be an adult female. Age determination was also estimated from dentition. The length and width of the occlusal surface, the number of plates, and wear pattern on the molars suggest that the animal was between the ages of 22 and 39. Geological field studies of the gravel pit locality led to the conclusion that the sediments containing the fossils are part of an ancient river system. Correlation of the deposits with nearby fluvial terraces indicate that the Fruitland fossils are likely middle Pleistocene in age. The discovery in 2011 of a partial mammoth humerus and additional bones in a different location within the gravel pit provided an opportunity for continued student research, including the collection of sediment samples. The objectives of this study include: 1) osteological studies to identify and measure each bone for comparison with known mammoth anatomical parameters, and 2) field studies of the stratigraphic, sedimentologic, and taphonomic context of the mammoth remains. This information may then be compared with other measured mammoth specimens to evaluate Pleistocene biogeographic patterns and add to the existing knowledge of past Idaho environments.