A QUANTITATIVE ANALYSIS OF FRACTURE PATTERNS DUE TO TRAMPLING ON MICROVERTEBRATES

Various taphonomic mechanisms, such as trampling, reduce the number of preserved specimens found in the fossil record. This study examines to what extent bone breakage of microvertebrates is influenced by bone shape, size, substrate and environmental condition. Understanding the influence of these variables on taphonomic processes when examining bone assemblages will provide invaluable evidence as to the conditions surrounding bones between burial and discovery. This study will test the hypothesis that weathered bones will break more easily than non-weathered bones and examine patterns of breakage among different taxa and size classes. Fresh and weathered disarticulated skeletons of six mice, frogs and rabbits, will be trampled by ungulates and analyzed for fracture patterns. Fractured bones will then be placed into the appropriate predetermined bone classification. Flesh was removed by dermestid beetles to avoid cuts or fractures made by tools. Disarticulated skeletons will be weathered by placing the bones under a 36.6°C heat lamp for 14 days. After the bones are trampled, they will be classified into four bone types: equant, platy, columnar and irregular based on original bone shape. Once classified, fresh and weathered bones will be examined for fracture patterns. Fractures will be measured and classified based on Outram’s Fresh Fracture Index (FFI; Outram,1998, 2001). It is predicted weathered bones will yield a FFI high number where as fresh bones will have a lower number.