This rail is related to the New Guinea flightless rail , Megacrex inepta , and the chestnut rail , Eulabeornis castaneoventris , all three Australasian genera probably being derived from Amaurornis ancestors . Storrs Olson argued that the genus Megacrex was so similar to Habroptila that Megacrex should be considered a junior synonym of Habroptila , resulting in two species in the genus . This was further lumped in Sidney Dillon Ripley 's 1977 monograph of the Rallidae ; he included Habroptila within the large genus Rallus . This suggestion was , however , not accepted by Gerlof Fokko Mees , who pointed out distinct differences in the shape and structure of the bill . A molecular phylogenetic analysis based on mitochondrial DNA sequence similarity found that Habroptila is part of evolutionary radiation within the broad genus Gallirallus that took place around 400 @,@ 000 years ago in the region .