Overview of the New, or Geometric Morphometrics

The new morphometrics, or geometric morphometrics, is a rapidly evolving field. “Morphometrics” has been used to describe a number of fields that study measurements of organisms, and that is why the modifier “new” or “geometric” is necessary to set aside the special subject matter discussed here: the shape of biological organisms as it is studied using as data, point coordinates in two or three dimensions. This includes landmark and outline coordinates. Landmarks are specific points on an organism that correspond in a sensible way over the forms being studied, that is they are homologs; while outline points do not share this notion of homology. The data of morphometrics is now being extended to include tangent directions at coordinates as well (see Bookstein and Green, 1993; Little and Mardia, this volume). Shape is primarily concerned with properties of coordinates that are invariant to scale, location and orientation (see Appendix I, Glossary). The current status of morphometrics together with some future objectives are summarized in a review by Rohlf and Marcus (1993a).