Studies of several species of planktonic Foraminiferida indicate that the spire of the generated coil is an important measure of species. The spire is easily measured and is logarithmic. Test and chamber growth dimensions measured in relation to the spire show that all species thus far studied exhibit nearly perfect geometric growth. Growth measurements taken in this manner allow the growth plan of individuals or assemblages of species to be compared statistically.

Such studies lead to a better understanding of variation within species and of the distinguishing morphologic characteristics of a species. Evolutionary change is better understood by investigating changes in growth dimensions with respect to the logarithmic spire. In paleoecologic studies of species populations, geographic variation can be quantified to yield a more precise analysis of paleoenvironmental parameters.

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