The Evolution Of Evolution

1060 Words5 Pages
Evolution is a theory that argues that all organisms alive on earth today share a common ancestor. It is thought that through generations, specific changes or adaptations were established in species in order to help them survive, reproduce, and raise offspring. But how are we certain that these changes occurred? Today, there is an abundant amount of research evidence that suggests that anatomical and physiological alterations occurred to species that caused them to turn from aquatic animals to terrestrial animals, allowing them to survive different environmental conditions. The following are several gradual changes an aquatic organism must go through in order to move to land and adjust to its new terrestrial habitat: circulatory and most importantly respiratory systems must be improved, structural adaptations should be modified, development of a skeletal system to protect the body and organs, and an adjustment of the senses must also occur. The evolution from water to land was a major event in the vertebrates. Species respiratory, circulation, and reproduction system show how they evolved and adapted to the environment. Vertebrates who belong the phylum Chordata had at least at some point of their life, a dorsal hollow nerve cord, a notochord, pharyngeal pouches, and a tail that extends beyond the anus. It is said that fishes were amongst the first vertebrates. The earliest fish to appear in the fossil record were jawless, covered with bony plates, gills, scales, but no fins. According to Arreola, they later evolved by adapting to their environment and began to form jaws and paired fins. The jaws were useful with their muscles and teeth, which helped them eat a wider variety of food, and were even able to defend themselves by bi... ... middle of paper ... a form of evidence that shows how life has changed throughout the years and how species today are connected way back to a common ancestor. Paleontologists look for features from one way of life to another. They create a tree of life that separates species according to their common structure. Fossils show how tetrapod legs evolved from fins and genes studies show how mutation and natural selection resulted into long limb bones from the fins (Hoff). In this case, they have uncovered how a species that lives on water transitioned to a terrestrial way of life. Perhaps descendants found land a source of abundant food and a haven from competition. Over millions of years through variation and selection, fins became legs, rear legs appeared, and bodies created fur and took the familiar shape the animals we have on land. These species had to evolve and change the way
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