This species was originally described as Montypythonoides riversleighensis based on vertebrae and an incomplete maxilla from the Late Oligocene to early Middle Miocene Riversleigh, Queensland. In the same paper Smith and Plane also described Morelia antiquus, based upon a dentary bone, a maxillary fragment, vertebrae, and some other bones. Scanlon (2001) examined the material and considered the remains of riversleighensis and antiquus to belong to the same species, and a species that belongs in the genus Morelia. The remains of M. antiquus were from the Camfield Beds of the Northern Territory and from the late Middle Miocene. Scanlon (2001) estimated Morelia riversleighensis to be in the 4 to 6 meter range and the sister species to the Oenpelli Python (Morelia oenpelliensis).