Amphibians have arisen in the lower or middle Devonian, ie, not less than 300 million years ago. Their ancestors were fish that have such light and paired fins of which could have developed five-fingered limbs. Meet these requirements crossopterygian ancient fish. They have light, but in the skeleton of the paired fins clearly detected elements homologous parts of the skeleton ground five-fingered limbs. The fact that the ancestors of amphibians were really ancient crossopterygian fish, also indicates a striking resemblance to cover their bones skull and crossbones skull Paleozoic amphibians. If you get more information, visit our site: BEST ESSAY CHEAP
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