BIOTIC

Evolution is one of the most powerful forces of nature, it creates and changes animals and other organisms according to climate, environment and oxygen levels... so how did it happen? In the beggining of the Devonian the tallest plants were only one meter tall! The ocean was crawling with life but, the land was quite bare. Among the animals who resided in the ocean was sea scorpions, ammonites, sae stars, crinoids, corals, sea urchins, brachiopods, jawless fish, primitive sharks, and lungfish; each organism played a key part in the evolution to come. The animal that developed most in the Devonian period was fish. By the end of the Devonian, fish had evolved so that they had skeletons and from fish with skeletons amphibians were born. Not all fish were the same, there were four types of fish with jaws, the Placoderms, the Acanthodians, the Sharks and the Bony fish. Acanthodians did not survive a later mass extinction and to this day no one knows their direct descendants. The placoderms ranged from 1 foot long to 30 feet long and were very well protected by a thick layer of skin, but they died out before the end of the Devonian. The REAL survivors were the sharks and the bony fish to whom we owe our lives. To this day bony fish make up 96 percent of the fish in the world. However fish were not the only animals around. During this time the first land animals were born, primitive lungs were developed and new possibilities opened for all organisms. Scientists have found evidence that clearly shows that homo sapiens have an ancestor who was some sort of bony fish but, no one yet knows which type.