Obtaining three-dimensional models of limb long bones from small mammals: a photogrammetric approach

Abstract

The use of two-dimensional (2D) pictures to analyse form variation of three-dimensional (3D) objectsentails measurement error, loss of important information and a possible misinterpretation of real shapechanges. Despite the increasing availability of 3D imaging technologies, many geometric morphometricanalyses of 3D objects are often performed on 2D images for several reasons. This issue is particularlyrelevant in the study of postcranial bones from small mammals, as devices precise enough for digitisingtiny objects are the most expensive ones. In this chapter, we describe a photogrammetric protocol toobtain 3D models of limb long bones from small mammals. The procedure is based on obtaining 2Dpictures from different angles using techniques of macro photography. To assess the usefulness of thismethod for geometric morphometric studies, we compare the form of the humerus between fossorial andsemiaquatic water vole species (genus Arvicola).