The first record of sexual dimorphism (difference in size between males and females) in a fossil bandicoot was reported from two new species from Riversleigh (Travouillon et al. 2014). Named "Madju variae" and "Madju encorensis", they are closely related to modern bandicoots, but do not fall in any modern family, as did "Galadi" and "Bulungu (genus)". Instead they are classified as Perameloid, with all known Peremelemorphian, to the exclusion of Yaralids. "Madju variae" is also unusual in preserving an ontogenetic series (age series from pouch young to adult), the second of any fossil marsupial mammal in Australia. The study of this ontogenetic series lead researchers to think that "Madju variae" developed slow than modern bandicoots, much more like a bilby, and therefore the rapid development of modern bandicoots must have evolved after the middle Miocene, when Australia started to become more arid.