THE MUSCULAR ANATOMY AND THE RESTORATION OF THE TITANOTHERES 



711 



Figure 648. — Heads of four titanotheres, showing 



progressive stages of development 



Front view. Modeled and drawn by E. s. Christman under the Figure 649. — Heads of four titanotlieres, showing progressive stages of development 



direction of William K. Gregory and H. F. Osborn. A, Eotitanops 



borealis. lower Eocene; B, Manteoceras mantcoceras, middle Eocene; Side view. Modeled and drawn by E. S. Christman under the direction of William K. Gregory and H. P. 



C, Proiitanotlierium emarginatum, upper Eocene; D, Brontotherium Osborn. H, Eotitanops borealis, lower Eocene; G, Manteoceras manteoceras, middle Eocene; F, Protilano- 



platyceras, lower Oligocene. One-ninth natural size. therium emarginatum, upper Eocene; E, Brontotherium platyceras, lower Oligocene. One-twelfth natural size. 



