Precambrian Stromatolites: Image Analysis of Lamina Shape

Abstract

A morphometric study of 808 lamina profiles of 18 previously published stromatolite taxa was performed using an image analyser. The data were plotted using different shape factors as coordinates and were subjected to multivariate statistical analysis. Visual inspection of the scatter diagrams allows similarities and differences to be readily perceived. Cluster analysis yielded similarity coefficients and dendrograms based thereon, providing quantitative statements of resemblance of lamina profiles. Three major groupings of lamina shape are recognized: (1) those with comparatively uniform, flattened convex profiles, associated with unbranching stromatolites or those with essentially parallel branches, (2) those with variable convex profiles, associated with divergent branches, and (3) those with conical laminae. Subsidiary groupings of more closely related taxa occur in each of the three groupings. The combination of image analysis and multivariate statistical analysis offers a practical and objective adju...