Intra and Inter-Assemblage Comparisons of Faunal Data Using Graphic and Moment Statistics

Conference Paper

Intra and Inter-Assemblage Comparisons of Faunal Data Using Graphic and Moment Statistics

Peter T. Bobrowsky

Abstract

All unbiased faunal assemblages can be shown to be lognormally distributed. This phenomenon is not unique to faunal remains, and it can be shown that this type of distribution is a common property of many other elements including artifacts and sediments. In fact, geologists have recognized for sometime that most sedimentary deposits show a lognormal distribution, but that each distribution can show minor variations. For example, modality, mean grain sizes, etc. can vary from sample to sample. Several parameters can be identified as characterizing individual sediment assemblages and quantitative descriptive measures have been developed to summarize these parameters. These measures include: median, mean, sorting, skewness, and kurtosis. The measures can be obtained through conventional moment statistical calculations or by graphic plotting methods. Both of these approaches have proven to be very useful in geologic studies and now occupy routine positions in geologic research. By analogy, the same parameters exist for faunal assemblages and, therefore, the same descriptors can be used to compare various faunal samples. This study illustrates the importance of using the above measures with historic faunal data from north-central Alberta.