Primates display a wide range of locomotor styles both within and between species. Even when classed as either arboreal or terrestrial, a single species or individual may use both substrates and a mixture of specific locomotor styles. Humans, as obligate bipeds, may be the most obvious exception, but even some humans can comfortably climb trees – we are not physically limited to terrestrial bipedalism alone. This high degree of locomotor flexibility may be one reason why the primate vertebral column varies so much. Among primates, the cervical spine remains stable at seven vertebrae, but the other regions (thoracic, lumbar, sacral and caudal) often vary much more in vertebral count and shape. This project aims to investigate variation in the number and morphology of vertebrae from head to tail in a range of primate species. To do this, we will collect photographs of vertebral morphology from digital databases for as many specimens as possible across species from all major non-human primate groups. We will also be collecting vertebral counts for each region from online specimens and a wide range of literature. Our analysis will focus firstly on identifying patterns in vertebral variation and secondly on how these patterns link to the different locomotive styles and degrees of locomotor flexibility exhibited by different species. Ultimately, our work will expand understandings of how and why variation occurs in the primate spine and the role that locomotor behaviour, development and evolution have played in shaping primate vertebral columns.