. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. f\^~) Spy Man Modern Man. Fig. 519. Changes in the chin-angle during the life of the individual. (On- togeny.) Compare with Figure 520. Fig. 520. Changes in the chin-angle during the his- tory of the race. (Phylog- eny.) Compare with Fig- ure 519. only mammalian skull bone that has an independent movement of its own. In man it has gone a long way, in adjustment to changing conditions, from its cartilaginous prototype still surviving in the dogfish. At no t
. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. f\^~) Spy Man Modern Man. Fig. 519. Changes in the chin-angle during the life of the individual. (On- togeny.) Compare with Figure 520. Fig. 520. Changes in the chin-angle during the his- tory of the race. (Phylog- eny.) Compare with Fig- ure 519. only mammalian skull bone that has an independent movement of its own. In man it has gone a long way, in adjustment to changing conditions, from its cartilaginous prototype still surviving in the dogfish. At no time in its history has there been any cessation in function, although upright posture and the resulting liberation of the hands, together with the effeminate modern days of soft cooked food, have made it no longer imperative for the jawbone to serve as a nutcracker and bonecruncher. In some monkeys and apes the lower jaw may make up as much as forty per cent of the total weight of the skull, but in modern man it falls to less than fifteen per Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Walter, Herbert Eugene, b. 1867; Sayles, Leonard Perkins, 1902-. New York : Macmillan Co.
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