Page 152 - The Origin of Birds and Flight

150 The Origin of Birds and Flight

structure that lets them use what they eat most efficiently. For example,
a growing stork gains 1 kilogram (2.204 pounds) of weight with every ki-
los (6.613 pounds) of food. The equivalent rate in mammals eating the
same foods is 1 kilo (2.204 pounds) of weight for 10 kilos (22.04 pounds).
Birds’ circulatory systems have also been created in line with their
high-energy requirements. The human heart beats an average of 78 times
a minute, in contrast to 460 times for a sparrow, and 615 for a humming-
bird. Since active flight requires a high level of energy, their blood circu-
lation takes place much more quickly than in terrestrial animals. The ox-
ygen needed for the high metabolic rate and energy expenditure is ab-
sorbed into the body by means of special lungs. Birds also differ signifi-
cantly from reptiles in having four-chamber hearts, compared to the
three chambers in reptiles’.

The Differences in Skulls and Jawbones
Comparisons between the skulls of the two groups also reveal no
similarity between them. As the result of an investigation carried out in
1999, Dr Andrzej Elzanowski, head of Vertebrate Zoology at the Polish
Zoology Institute, concluded that “there are no similar features between
the jaw and palate in theropod dinosaurs and those in birds.” 109
Compared to reptiles and other four-footed creatures, most of the
bones in birds’ skulls and rear legs are very different. 110
On the other hand, the ophthalmic nerves in all theropods extend
around the skull together with certain other nerves. In birds, however,
those same nerves pass through special holes in the front of the skull.
Therefore, every stage of evolutionists’ search for similarities has ended
in disappointment.
Furthermore, a bird’s facial structure bears absolutely no resem-
blance to any reptile’s. Fish, reptiles, amphibians and all mammals open
their mouths by lowering their jawbones. Their upper jaws are immo-
bile, since they are a fixed part of their skulls. Instead of jaws, however,
birds have beaks and, in contrast to other animals, they are able to raise
the upper part of their beaks as well as lowering the bottom section.