Huxley, in 1868, divided the carinate birds into Dromaeo-, Schizo-, Desmo-, and Aegithognathae, an arrangement which for many years had a considerable influence upon classification.
Huxley recognized the Psittacomorphae as forming one of the principal groups of Carinate birds, and they are now generally regarded as forming a suborder Psittaci of the Cuculiform birds (see Bird).
This genus was already typically developed in late Miocene times, and with a very wide geographical distribution (see Bird, Fossil), but of the affinities of the other midand early tertiary flightless birds we know nothing, and it must be emphasized that we should probably not be able to classify a truly ancestral Ratite, namely, a bird which is still to a certain extent carinate and not yet ratite.
He concisely cites (p. 238) no fewer than eight other characters of more or less value as peculiar to the Carinate Division, the first of which is that the feathers have their barbs furnished with hooks, in consequence of which the barbs, including those of the wing-quills, cling closely together; while among the rest may be mentioned the position of the furcula and coracoids, 4 which keep the wing-bones apart; the limitation of the number of the lumbar vertebra to fifteen, and of the carpals to two; as well as the divergent direction of the iliac bones - the corresponding characters peculiar to the Ratite Division being the disconnected condition of the barbs of the feathers, through the absence of any hooks whereby they might cohere; the non-existence of the furcula, and the coalescence of the coracoids with the scapulae (or, as he expressed it, the extension of the scapulae to supply the place of the coracoids, which he thought were wanting); the lumbar vertebrae being twenty and the carpals three in number; and the parallelism of the iliac bones.
Their body is generally compressed and slender; their broad ventral scutes are often carinate on the sides.
Shell with short spire, carinate and pointed.
Iv., Boston, 1885) gave the Impennes independent rank equivalent to the rest of Carinate birds; M.