Another bird of the same
period and region (Gastornis) stood about ten feet high, and must
have looked something like a wading ostrich. Other large waders,
even more ostrich-like in structure, lived in North America; and
in Patagonia the remains have been found of a massive bird, about
eight feet high, with a head larger than that of any living
animal except the elephant, rhinoceros, and hippopotamus
(Chamberlin).
The absence of early Eocene remains prevents us from tracing the
lines of our vast and varied bird-kingdom to their Mesozoic
beginnings. And when we appeal to the zoologist to supply the
missing links of relationship, by a comparison of the structures
of living birds, we receive only uncertain and very general
suggestions.* He tells us that the ostrich-group (especially the
emus and cassowaries) are one of the most primitive stocks of the
bird world, and that the ancient Dinornis group and the recently
extinct moas seem to be offshoots of that stock. The remaining
many thousand species of Carinate birds (or flying birds with a
keel [carina]-shaped breast-bone for the attachment of the flying
muscles) are then gathered into two great branches, which are
"traceable to a common stock" (Pycraft), and branch in their turn
along the later lines of development.
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