A newly described fossil mammal from the Cretaceous of China is challenging a long-held assumption about mammalian evolution. Unlike modern mammals, which typically grow only two sets of teeth in a lifetime, this ancient species appears to have been capable of replacing its teeth continuously, a trait more commonly associated with reptiles.
The fossil, reported by New Scientist, shows dental features that resemble those of reptiles. The researchers suggest that this pattern of tooth replacement may have been the ancestral condition for mammals, with the familiar two-set system evolving later. If confirmed, the discovery would push back the origin of continuous tooth replacement and reshape our understanding of how mammalian dentition evolved.
The study is based on a single fossil specimen, so the authors caution that more material is needed to fully understand the animal's life history. Still, the finding adds a new piece to the puzzle of early mammal diversity and the evolutionary paths that led to modern teeth. As the source notes, it changes the picture of our evolution by showing that some ancient mammals retained a more reptilian way of{