Intracoenosteal variation in a Devonian stromatoporoid



Fagerstrom, J. A. & Saxena, K. M. L.: Intracoenosteal variation in a Devonian stromatoporoid.

Statistical analysis of four different features of coenosteal morphology measured in sixteen randomly distributed vertical and tangential thin sections from a specimen of Syringostroma sherzeri (Grabau) from the Detroit River Group near Ingersoll, Ontario, indicates that although the degree of variation is very high, the variation in a single section is representative of the variation in the entire coenosteum. This discovery may therefore be regarded as a partial vindication of current practice in stromatoporoid taxonomy of baaing identifications on examination of one vertical and one tangential sectior. Furthermore, this study indicates that certain morphological features are less variable than others and are therefore of greater value as taxonomic criteria. In cases where the number of measurements per section is small, tests of the significance of differences based on a comparison of the medians, rather than means, is preferred because such tests do not assume that the data are normally distributed.