Morphometrics in the Study of Ediacaran Fossil Forms

Abstract

The evaluation of fossil shapes is the primary goal in the study of paleontology. Unlike biologists who are able to utilize an animal’s behavior, soft tissue anatomy, and molecular make-up to study species, paleontologists must concentrate on phenotypical approaches that rely on morphological differences between fossil populations. Morphometric methods which quantify form and shape are extremely powerful tools for assessing questions related to taxonomy, ­morphospace occupation, morphological disparity or taxon-free estimates of diversity, competition between taxa, ecological character displacement, predatory defense, changes in predatory behavior, anatomical responses to environmental change, and much more. The developing field of morphometrics attempts to mathematically describe shape variations between individuals and can be used to statistically evaluate correct species assignment, isolate shape changes, or identify regions within a phenotype where shape changes are most variable or pronounced. Traditional morphometric approaches focus on the evaluation of several distance measurements taken within a series of specimens, while geometric morphometrics replaces distance-based ­measurements by evaluating the displacement of corresponding anatomically important locations on specimens which are termed landmarks. Both traditional and geometric morphometric methods allow for the comparison of large samples through a variety of multivariate statistical techniques, many of which will be explored in this chapter. Considering the relative difficulty of characterizing the taxonomic affinities of Precambrian life, paleontologists have adopted ­morphometric techniques to help elucidate the true diversity of early life.