ANCESTRY OF SCREAMERS 
The horn on the head must therefore be either a sexual 
adornment or a relic from the past. In the latter 
case it may perhaps be looked upon as an inheritance 
from those long since defunct and bird-like reptiles, 
the Dinosaurs ; and like an armorial bearing of a military 
kind, be rather a mark of aristocracy than an indication 
of a pugnacious and offensive character. We have 
SCREAMER, 
intimated that the screamers are of ancient lineage. 
That conclusion is accepted on account of the fact that 
they cannot be definitely referred to any existing group 
of birds, coupled with certain traces of reptilian con- 
ditions in their organization. The most noteworthy of 
these is the character of the ribs, which have not, as 
have all other existing birds without exception, certain 
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