Mandibular Hypodontia and Osteoarthritis in Prehistoric Bighorn Sheep (Ovis canadensis)in Eastern Washington State, USA

摘要

Mandibular hypodontia of the p2 was found to occur in 3 out of 21 individual prehistoric RockyMountain bighorn sheep (Ovis canadensis canadensis) from Moses Coulee Cave in easternWashington State, similar to its frequency of occurrence in modern bighorn. There is noevidence of lumpy jaw (mandibular osteomyelitis) in the Moses Coulee Cave collection.Evidence from Moses Coulee Cave aligns with the hypothesis that low frequencies ofhypodontia and lumpy jaw occur in healthy, evolutionarily old (maintenance) populationsin order to maintain the occlusal area and thus maximise efficiency of food procurement andprocessing. Osteoarthritis was found to occur in 1 out of 70 individual Rocky Mountain bighornsheep (Ovis canadensis canadensis) astragali in the Moses Coulee Cave collection. Thisprevalence is unsurprising given a population dominated by prime-age individuals. Osteo-arthritis was likely selected against given that individuals must be agile to effectively userugged terrain to escape predation and as a general measure suggests a healthy population.