Allison Machnicki

The thoracolumbar spine is crucial for understanding primate evolution and the unique adoption of human bipedalism. Both great apes and humans have stabilized their spine with the posterior shift of the transitional vertebra and reduction of non-ribbed lumbar vertebra.There is debate regarding whether these features are homologous or homoplastic. Genetic modification of Hox9 in mice results in the independent modification of rib count and transitional vertebra placement, mimicking caudalization of the transitional vertebra in hominoids. We propose to compare the morphology of the primate transitional vertebra in museum collections and experimentally modified mice. We will conduct quantitative and qualitative analyses on primate and Hox9 modified mouse thoracic and lumbar columns using 3D and micro-CT scanning and a large osteological dataset.