Geometric Morphometrics for Biologists: A Primer, Third Edition succeeds the second edition of this text as the primary resource for teaching modern geometric methods of shape analysis to students, researchers, and practicing scientists in the field of organismal biology. These geometric methods allow for the study of biological shape by incorporating the geometry of organisms throughout data analyses. This work retains and updates methodologies that remain relevant to the field to ensure clear and effective instruction to audiences new to this branch of data analysis. Novel content on phylogenetic comparative methods, evolutionary morphology, analyses of disparity, genetics of shape, and simulating shape data has been added. Written by longtime experts Miriam Zelditch and Donald Swiderski, Geometric Morphometrics for Biologists effectively introduces complex mathematical concepts in a manner accessible to all readers. This edition delivers step-by-step guidance for how to effectively utilize updated analytical software. It is an immensely valuable introduction for students and practicing biologists interested in learning applications of multivariate statistics and matrix algebra to organismal biology.