Scientists from the Museum für Naturkunde Berlin, together with collaborators from South Africa and the U.S., have revealed a new chapter in the history of the mammalian breastbone. Their study of a 260-million-year-old fossil shows that its breastbone was divided into a series of segments, like that of modern mammals. This discovery indicates that prerequisites of the mammalian way of walking and breathing were already present in some distantly related Permian ancestors.