What is a cursorial mammal?

Abstract

This paper focuses on the concept of cursoriality in mammals and aims to point out the confusion that can arise when a classical term is not explicitly redefined or expanded to incorporate the results of biomechanical techniques. Historically, the definition of ‘cursorial’ was based qualitatively on an animal's morphology and behaviour, generally referring to large, terrestrial mammals that ran fast or far across open spaces. However, in recent years, as biomechanicists have learned how to quantify aspects of limb movement and bone orientation, a more specific meaning of this term has come into use. Results from these new techniques have highlighted the lack of specificity in the historical definition and have led us to propose a clarified, quantitative definition of ‘cursorial’. The exceptional nature of bovids and primates with respect to this new definition is also addressed in our analysis. We recognize that the definition we propose is, itself, not sufficient because it cannot be applied to fossil taxa and because kinematic data are still lacking for many taxa. Hence, we look forward to the eventual adoption of an even more expanded definition or suite of terms that will further distinguish between all attributes of cursorial mammals and that will reflect an increased understanding of their evolutionary origins.