Answer to Question #99260 in Zoology for Helen Najera

Question

What information about the Devonian tetrapods leads to the conclusion that tetrapods evolved in the water rather than on land?

Answer 1

The common ancestor of tetrapods vertebrate had fins (with lepidotrichia), scales, gills, and lived in the water.They also had air bladders (air-filled sacs) connected to the back of their throats that could be used for breathing air (i.e., as lungs) or for buoyancy control. The air bladders of many ray-fins no longer connect to their throats, and so they are not able to breathe air. In these ray-fins, the air bladder is used mainly for buoyancy control and is known as a swim bladder.However, tetrapods have taken an alternative route: they have lost the buoyancy control function of their air bladders, and instead this organ been elaborated to form the lungs that we all use to get around on land.