A Bandicoot is any of about 20 species of small to medium-sized, land marsupial omnivores in the order Peramelemorphia. The other two species of peramelemorphs are the bilbies.
Classification within the Peramelemorphia used to be simple. There were thought to be two families in the order. There are short-legged mostly herbivorous bandicoots, and the longer-legged nearly carnivorous bilbies. In recent years, it has become clear that the situation is more complex. First, the bandicoots of the New Guinean and far-northern Australian rainforests were deemed distinct from all other bandicoots. These were grouped together in the separate family Peroryctidae. More recently, the bandicoot families were reunited in Peramelidae, with the New Guinean species split into four genera in two subfamilies, Peroryctinae and Echymiperinae. The “true bandicoots” occupy the subfamily Peramelinae. The only exception is the extinct Pig-footed Bandicoot, which has been given its own family, Chaeropodidae.
The embryos of bandicoots, unlike other marsupials, form a placenta-like organ that connects it to the uterine wall. The function of this organ is probably to transfer nutrients from the mother. The structure is small compared to those of the placentalia.