Page 130 - The Origin of Birds and Flight
P. 130
Birds’ special respiratory sys- Their digestive system that
tem constantly meets their high makes the most efficient use of
oxygen requirements. food to meet their energy con-
sumption.
Their skeletal system con- Their light, flexible feathers
sists of conjoined bones that with their unique aerodynamic
are light, strong, but hol- structure are ideal for flight.
low—ideally suited to flight.
