Investigating Best Practices for Applying a Quantitative Tooth Complexity Metric to Fishes

Although fishes constitute nearly half of all known vertebrate diversity, their dentitions remain remarkably understudied. This is due in part to the challenges of continual tooth replacement, high variation in tooth form and number along the jaws, and a two-jaw system that allows for prey capture and processing to be decoupled. To help address this gap in our knowledge, we provide a guide to best practices when implementing Orientation Patch Count Rotated (OPCR) to measure tooth surface complexity in fishes using microCT scans. OPCR has been successfully applied across numerous studies of mammal and reptile dentitions but is yet to be applied to fishes. We provide an open-source 3D-OPCR workflow for fish dentitions along with the results from five investigations that illustrate how methodological choices relevant to implementing OPCR in fishes can impact OPCR output. Our goal is to provide comparative biologists with a useful framework that leverages open access software to conduct their own integrative studies on dental complexity in fishes and other vertebrates where whole jaw analyses are useful. We view 3D-OPCR as a powerful but underutilized tool for quantifying patterns of dental variation in fishes that has potential for cross-disciplinary application within the integrative and comparative biology community.