User:Jtwsaddress42/Quotes/Romer, Alfred Sherwood 1972d

Evolution of the Pharyngeal Arch Cartilages and the Striated Visceral Musculoskeletal System "In every vertebrate there is a set of well-developed striated muscles associated with the anterior part of the digestive tract, most notably the pharynx. In fishes there is an important series of muscles, lying along the walls of the pharyngeal region, which effect opening and closing of the gill slits.  In jaw-possessing fishes there are powerful muscles associated with jaw movements; it is universally agreed that the jaws represent a modified and enlarged series of gill bars, and these jaw muscles are clearly a special part of the pharyngeal series. 		In tetrapods the jaw muscles remain prominent, but the gills are lost;  much of the original gill musculature disappears, but a few small muscles persist in the throat and ear region, the trapezius muscle system of the neck is a further persistent relic, and in mammals the muscles of expression are an outgrowth of the same set of muscles."

Alfred Sherwood Romer (1972)