Comparison of embryonic development, from HH21 to HH40, between ostrich (Struthio camelus) and chicken (Gallus gallus).

This study should greatly aid ostrich-related developmental and morphological research and provide a reference for studying the development and evolution of avian limb skeletons, including molecular research. Questions that can now be addressed include studies into the fusion of tarsometatarsal skeleton, ossification, and digit loss.