Structural characters no less important separate the rheas from the emeus; the former can be readily recognized by the rounded form of their contour-feathers, which want the hyporrhachis or after-shaft that in the emeus and cassowaries is so long as to equal the main shaft, and contributes to give these latter groups the appearance of being covered with shaggy hair.
56-62); it resembles in its general configuration that of the emeus and cassowaries, while it differs from that of Apteryx most obviously by the short and stout bill.
In this respect cassowaries and emeus hold an intermediate position, their occasional zoophagous (especially piscivorous) inclination being well known.
Parker recognizes five genera, with about twenty species, which he combines into three sub-families: Dinornithinae with Dinornis, Anomalopteryginae with Pachyornis, Mesopteryx and Anomalopteryx, comprising the comparatively least specialized forms; and Emeinae with the genus Emeus, not to be confounded with the vernacular emeu.
Further, it is the opinion of competent ornithologists that there is affinity of the Australian emeus and cassowaries with the New Zealand moas and with the Malagasy Aepyornis.