FrogWorld

Evolutionary Roots: Adaptations to a New World There were many advantages for amphibians on land. There was abundant food and shelter and a lack of predators. The ability to move from one water source to another also gave amphibians a distinct advantage over the other aquatic animals at the time. But there were many disadvantages as well. Without water, it was difficult for early amphibians to support their own body weight. Constantly changing temperatures made keeping a stable internal temperature extremely difficult and skin that needed to be constantly moist easily dried in the air. To adapt to their new environment, amphivbians developed special characteristics. Their hearts evolved to have three chambers instead of two, like their fish ancestors. This allowed a more efficient method of blood circulation, and therefore increased the amount of oxygen carried to body cells. Lungs were developed to allow amphibians to breathe, though the skin became a more important organ in respiration. The limbs slowly moved farther under the body to give better support. The first frogs evolved 190 million years ago during the Mesozoic Era. Previous