IV. CORACIOMORPHAE = Cuculiformes + Coraciiformes + Passeriformes.
These four legions are again combined into two “Brigades,” the first of which comprises the first and second legions, while the second brigade contains the third and fourth legions.
Thus the whole classification becomes a rounded-off phylogenetic system, which, at least in its broad outlines, seems to approach the natural system, the ideal goal of the scientific ornithologist. The main branches of the resultant “tree” may be rendered as follows:—
The Odontolcae seem to be an early specialized offshoot of the Colymbo Pelargomorphous brigade, while the Ratitae represent a number of side branches of early Alectoromorphae. The Ratitae branched off, probably during the Eocene period, from that still indifferent stock which gave rise to the Tinami + Galli + Gruiformes, when the members of this stock were still in possession of those archaic characters which distinguish Ratitae from Carinatae. It follows that new groups of Ratitae can no longer be developed since there are no Carinatae living which still retain so many low characters, e.g. configuration of the palate, precoracoid, pelvis, intestinal convolutions, copulatory organ, &c. Loss of the keel is co-ordinated with the power of using the forelimbs for locomotion; although a “Ratite” character, it is not sufficient to turn a Notornis, Cnemiornis or Stringops, not even a Phororhacos into a member of the Ratitae.
Another branch of the Alectoromorphae, in particular of the Galliformes, when these were still scarcely separated from the Gruiformes, especially rail-like birds, leads through Opisthocomi to the Cuculiformes. These are, again in an ascending direction, connected with the Coraciiformes, out of which have arisen the Passeriformes, and these have blossomed into the Oscines, which, as the apotheosis of bird life, have conquered the whole inhabitable world.
(H. F. G.)
[1] Treviranus, Biologie oder Philosophie der lebenden Natur, vol. ii. cap. 4, § 2 (Göttingen, 1803).
[2] F. Tiedemann, Anatomie und Naturgeschichte der Vögel, vol. ii §§ 127-255 (Heidelberg, 1814).