Abstract
The author presented a new concept in the development of the phonatory organ of vertebrates. This concept was based on his own studies and other works in comparative anatomy. The evolution of the phonatory organ is developed from the same trunk from lung fish to reptile in the evolutionary tree, and divides into two branches. One branch is the route from reptile to bird, the other branch is the route from reptile to mammal. In the first branch, the lower part of the trachea just attached to the air sac develops to create the syrinx in the bird and is called the air-bladder system. In the second branch, the upper part of the trachea developed into a preventive mechanism for aspiration, forming the vocal fold, and is called the larynx system.
