Page 88 - The Evolution Impasse 2

86 Origin of the Avian Lung

par a bron chi even tu al ly join up to geth - struc tures is pos si ble. Any ver te -
er again, form ing a true cir cu la to ry brate must breathe in or der to sur -
sys tem so that air flows in one di rec - vive, and the first step in any change
tion through the lungs. . . [T]he struc - of pul mo nary struc ture would lead
ture of the lung in birds and the over -
to the death of that in ter me di ate
all func tion ing of the re spir a to ry sys -
stage.
tem is quite unique. No lung in any
Furthermore, the the o ry of ev o lu -
oth er ver te brate spe cies is known
tion main tains that all chan ges took
which in any way ap proach es the avi -
place grad u al ly, over mil lions of
an sys tem. Moreover, it is iden ti cal in
years. Yet no crea ture whose lungs
all es sen tial de tails in birds as di verse
do not func tion can sur vive for more
as hum ming birds, os trich es and
hawks. 83 than a few mi nutes.
In his book A Theory in Crisis,
It is im pos si ble for the rep til i an
Michael Denton sets out the im pos si -
lung, with its two-way air flow, to
bil i ty of ex plain ing the or i gin of the
have evolved in to the avi an lung,
avi an lung from an ev o lu tion a ry
with a one-way flow. No tran si tion al
per spec tive:
stage be tween these two pul mo nary