John Hunter, an associate professor in the Department of Evolution, Ecology and Organismal Biology at Ohio State Newark, has published an invited commentary in Proceedings of the Royal Society B: Biological Sciences. “A new approach to an old problem: homology of postcanine teeth in therian mammals” addresses a problem zoologists have been considering for almost 200 years: if and how the development of premolars and molars in marsupials and placental mammals is connected, and whether recent fossil discoveries suggest a need to challenge prevailing views in the field.