Bandicoots’ teeth say carnivore; their feet say kangaroo
Bandicoots and bilbies, the marsupial order Peramelemorphia, live only in Australia and New Guinea. Their teeth resemble those of marsupial carnivores, while their fused hind toes match kangaroos and wombats, a contradiction that long left scientists unsure where the group belongs on the marsupial tree.
Most members share the classic bandicoot build: a plump, arched body, a long finely tapering snout, big upright ears, slender legs and a thin tail. They weigh from about 140 grams to 4 kilograms, though a kilogram is typical. Their mouths hold three pairs of lower front teeth, the pattern seen in the carnivorous dasyurids, yet the second and third toes of the hind foot are fused, a trait otherwise typical of the herbivorous diprotodonts such as kangaroos, wombats and possums.
Researchers proposed rival fixes: either bandicoots came from carnivores and evolved fused toes separately, or they descended from possum-like ancestors and regained the extra teeth, or they began as primitive carnivores whose toe fusion arose as a specialisation. Molecular studies have since given a well-supported family tree. The bilbies, genus Macrotis, split off first, followed probably by the recently extinct genus Chaeropus, with the remaining bandicoots forming the family Peramelidae.
Fossils were slow to appear. R. A. Stirton described the first extinct species in 1955 from a Pliocene jaw found in the Tirari Desert of central Australia. Archer and Wade added a single molar from Bluff Downs in Queensland in 1976, and in 1995 Jeannette Muirhead named Yarala burchfieldi from Riversleigh, smaller than any living bandicoot, with a skull found in 2000.
Riversleigh has kept yielding surprises. Galadi speciosus had a short snout, hinting at a more meat-based diet than its omnivorous descendants, and the mouse-sized genus Bulungu includes a species about 24 million years old, the oldest bandicoot known in 2013. In 2014 researchers described the oldest modern bandicoot, about 15 million years old and named Crash bandicoot after the video game hero, along with the first fossil evidence of size differences between the sexes.
Source: Peramelemorphia
