This provided the context for an extreme diversification of fish across the world. Within the evolution of the jaw, there are general patterns of predatory and defense mechanisms, as well as the construct of the armor of modern fish. With the evolution of jaws in fish, there was much less of a need for body armor for protection. Rather, the fish stepped out of the prey position and into a predatory one with the advantages of the jaws. Thus, they came to have less predators themselves, and so less of a need for protection armor. Many early fish, such as the Coccosteus, which was serves as an evolutionary bridge between the fully armored fish of prehistoric times to the modern sleek and armor less fish of today, (Benton & Harper 2009). Also, their jaws served as a protection measure in themselves, which also helped reduce the level of external armor for fish. Modern fish today have much less armor then their much earlier predecessors. Thus, the evolution of the jaw was responsible for a wide array of morphology developments; "Fish became more agile to be better predator, they were able to reduce their armor because they were les vulnerable, and their muscle density was able to decrease because they no longer led such a sluggish lifestyle," (Kagle 1997:1). The evolution of teeth within the jaw context depended greatly on the individual habitat which bred the world's fish. Each individual species followed different evolutionary paths based primarily on the food available within their habitats. For example, teleost fish tend...

Thus, another aspect of fish morphology was influenced by jaws. Some fish, like the lung fish, developed flat teeth to grind invertebrates which comprised their diet (Benton & Harper 2009). The evolution of other species such as the sharks produced animals that now have entirely cartilage frames other then the bone within their jaws. The cartilage allows for swifter movement, creating the possibility of the ultimate ocean predator. Therefore, the make up of the musculature of fish changed dramatically based on the evolution of the jaws. Fish became much faster and more agile, eventually becoming the swift creatures we know them as today. Fish have developed both predatory and defensive behaviors thanks to the evolution of his jaws, "jaws allowed defensive behaviors that these fished could use both intra- and inter-specifically and offered them greater opportunities to manipulate the environment in building nests or grasping mates," (Strickberger 2000:402). The evolution of the jaw was a critical step in the diversification of the larger body of fish species.
References

Benton, Michael J. & Harper, David a. (2009). Introduction to Paleobiology and the Fossil Record. 1st ed. Wiley-Blackwell.

Kagle, Rebecca. (1997). The evolutionary steps of fish. Serendip. Retrieved October 26, 2009 at http://serendip.brynmawr.edu/exchange/node/1904

Strickgerger, Monroe…