"Although attaining a height of fifteen to sixteen feet the trachodons were not covered with scales or a bony protecting armature, but with dermal tubercles of relatively small size, which varied in shape and arrangement in different species, and not improbably associated with this varied epidermal pattern there was a varied color pattern. The theory of a color pattern is based chiefly upon the fact that the larger tubercles concentrate and become more numerous on all those portions of the body exposed to the sun, that is, on the outer surfaces of the fore and hind limbs, and appear to increase also along the sides of the body and to be more concentrated on the back. On the less exposed areas, the under side of the body and the inner sides of the limbs, the smaller tubercles are more numerous, the larger tubercles being reduced to small irregularly arranged patches. From analogy with existing lizards and snakes we may suppose, therefore, that the trachodons presented a darker appearance when seen from the back and a lighter appearance when seen from the front.
[Illustration: Fig. 31.--The Dinosaur Mummy. Detail of skin of under side of body. _After Osborn_]
[Illustration: Fig. 32.--Skin impression from the tail of a _Trachodon_. The impressions appear to have been left by horny scutes or scales, not overlapping like the scales on the body of most modern reptiles, but more like the scutes on the head of a lizard.]
[Illustration: Fig. 33.--Skull of Gila Monster (_Heloderma_), for comparison of surface with skin impressions of _Trachodon_. Enlarged to 4/3.]
"The thin character of the epidermis as revealed by this specimen favors also the theory that these animals spent a large part of their time in the water, which theory is strengthened by the fact that the diminutive fore limb terminates not in claws or hoofs, but in a broad extension of the skin, reaching beyond the fingers and forming a kind of paddle.[18] The marginal web which connects all the fingers with each other, together with the fact that the lower side of the fore limb is as delicate in its epidermal structure as the upper, certainly tends to support the theory of the swimming rather than the walking or terrestrial function of this fore paddle as indicated in the accompanying preliminary restoration that was made by Charles R. Knight working under the writer's direction. One is drawn in the conventional bipedal or standing posture while the other is in a quadrupedal pose or walking position, sustaining or balancing the fore part of the body on a muddy surface with its fore feet. In the distant water a large number of animals are disporting themselves.