Kagu name "Rhynochetos", and the clade name Rhynochetidae, are derived from the Greek "rhis" meaning nose and "chetos" meaning corn, referring to the corn-shaped flaps over the nostrils. The specific name "jubatus" is derived from the Latin "iabatus" meaning crested. The name kagu is derived from the Melanesian names for the species. The species is variously known as the "kavu" or "kagou" in the Kanak languages, and as the "cagou" in French (also used as an alternative spelling in English). The kagu is a ground-living bird, in length. The weight can vary considerably by individual and by season, ranging from .
Lowland kagu of the lowland kagu are very similar to those of the kagu. They differ in the greater size of the extinct species in averaging about 15% larger, with no overlap between the hindlimb elements and only rare overlap between those of the wings. The describers postulate that "R. orarius" and "R. jubatus" were lowland and highland forms, respectively. Lowland kagu The lowland kagu ("Rhynochetos orarius") is a large, extinct species of kagu. It was endemic to the island of New Caledonia in Melanesia in the south-west Pacific region. It was described from subfossil bones found at the Pindai Caves paleontological