Figure 1.10   Statistical study of the Permian brachiopod Dielasma. Two measurements, sagittal length (L) and maximum width (W) were made on all specimens. The size–frequency distributions (a, b) indicate an enormous number of small shells, and far fewer large ones, thus suggesting high juvenile mortality. When the two shape measurements are compared (c), the plot shows a straight line (y = 0.819x + 0.262); on a previous logarithmic plot, the slope (a) did not differ signifi cantly from unity, so an isometric relationship is assumed, and the raw data have been replotted.

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