A radiographic study of the extent of variation in cortical bone thickness in soay sheep

In order to assess the effect of nutrition on bone mass, radiographs of metopodia from skeletal collections of Soay sheep (Ovis aries) were taken of animals subject to seasonal stress (from the island of Hirta, Hebrides) and those living in good nutritional conditions (from the Institute of Animal Physiology, Babraham, Cambridge). A third set of radiographs was taken at 3 month intervals over a single year on living Soay sheep kept under good conditions at the Rowett Research Institute, Aberdeen.Measurements were taken on the radiographs of length, minimum shaft width (SW) and medullary cavity width (MCW), while combined cortical thickness (CCT) was calculated. The ewes from Hirta had significantly lower values for CCT than those from Babraham, whereas the rams showed no significant reduction in CCT. Since no seasonal variation in CCT was detected in the well nourished Rowett ewes, this indicates a differential effect of poor environmental conditions on bone metabolism in ewes. It is proposed here that this may be related to the additional stress imposed by gestation and lactation on female animals living under conditions of seasonally restricted food supply.     

A dental microwear study of seaweed‐eating and grazing sheep from Orkney

The potential of dental microwear for recognizing the use of seaweed as fodder in the past is explored through the analysis of microwear patterning in modern seaweed‐eating and grazing sheep from Orkney. Seaweed‐eating and grazing sheep are clearly distinguished on the basis of microscopic dental wear patterns. This reflects an emphasis on anterior‐posterior jaw movements and large pitted features in the seaweed‐eaters and can be attributed to the differing forces and/or masticatory movements required in the comminution of grasses and seaweed. Differences between seaweed‐eating and grazing individuals are maintained when the grazing group is expanded to include grazing sheep from Greenland and the Scottish borders. It is concluded that the microwear of seaweed‐eating sheep is highly distinctive and that dental microwear analysis potentially has a widespread application for identifying seaweed grazing within Scotland and the North Atlantic islands. Copyright © 2000 John Wiley & Sons, Ltd.     

Digital cementum luminance analysis (DCLA): a tool for the analysis of climatic and seasonal signals in dental cementum

Cementum banding patterns have been used by archaeozoologists and wildlife managers for a number of decades to assess the season and age at death of mammalian populations. However, the observation and measurement of the nature of cementum banding, especially that of the final band, has proved to be difficult except under conditions of excellent preservation and advanced microscopy. The research presented here details a method for extracting luminance data from the banding patterns of cementum in order to quantify the optical properties of cementum tissue. By doing so, analysis of the relationship between cementum deposition and environmental variables is achieved. We present the results of a digital cementum luminance analysis (DCLA) on a sample of first molars from two species, Ovis aries, Soay and Capra ibex. The results indicate that significant relationships occur between seasonal temperature changes and cementum histology. Furthermore, we show that luminance values can be used to assess the geographical range of genetically similar populations. Our results demonstrate that the study of luminance is a vital tool for the quantitative study of dental cementum for both archaeological and ecological studies. Copyright © 2007 John Wiley & Sons, Ltd.