sentences:  Within the grass parrot genus "Neophema", it is one of four species classified in the subgenus "Neonanodes" and is most closely related to the orange-bellied parrot ("N. chrysogaster"), the other two species being the blue-winged ("N. chrysostoma") and elegant parrot ("N. elegans").A burrow-nester, the rock parrot has evolved from a lineage of tree-nesting ancestors.The biologist Donald Brightsmith has proposed that several lineages of parrots and trogons switched to nesting in burrows to avoid tree-living mammalian predators that evolved and proliferated in the late Oligocene to early Miocene (30–20 million years ago).