52 THE AMERICAN MUSEUM JOURNAL 
under the body rather than in a crawling attitude with the belly close to 
the ground, as is common among living reptiles. 
Trachodonts lived near the close of the Age of Reptiles in the Upper 
Cretaceous and had a wide geographical distribution, their remains 
having been found in New Jersey, Mississippi and Alabama, but more 
commonly in Wyoming, Montana and the Dakotas. A suggestion of 
the great antiquity of these specimens is given by the fact that since the 
animals died, layers of rock aggregating many thousand feet in vertical 
thickness have been slowly deposited along the Atlantic coast. 
The bones of the erect specimen are but littie crushed, and a clear. 
conception of the proportions of the animal can best be obtained from 
this specimen. It will be seen that the Trachodon was shaped somewhat 
like a kangaroo, with short fore legs, long hind legs and a long tail. 
The fore limbs are reduced indeed to about one sixth the size of the hind 
limbs, and judging from the size and shape of the foot-bones, the front 
legs could not have borne much weight. They were probably used in 
supporting the anterior portion of the body when the creature was 
feeding, and in aiding it to recover an upright position. ‘The specimen 
represented as feeding is posed so that the fore legs carry very little of 
the weight of the body. There are four toes on the front foot, but the 
thumb is greatly reduced, and the fifth digit, or little finger, is absent. 
The hind legs are massive and have three well-developed toes ending 
in broad hoofs. The pelvis is lightly constructed with bones elongated 
like those of birds. The long, deep, compressed tail was particularly 
well adapted for locomotion in the water. It may also have served to 
balance the creature when standing erect on shore. The broad, ex- 
panded lip of bone known as the fourth trochanter, on the inner posterior 
face of the femur, or thigh bone, was for the attachment of powerful 
tail muscles similar to those that enable the crocodile to move its tail 
from side to side with such dexterity. This trochanter is absent from 
the thigh bones of land-inhabiting dinosaurs with short tails, such as 
Stegosaurus and Triceratops. ‘The tail muscles were attached to the 
vertebrae by numerous rod-like tendons which are preserved in position 
as fossils on the erect skeleton. Trachodonts are thought to have been 
expert swimmers. Unlike other dinosaurs their remains are frequently 
found in rocks that were formed under sea water, probably bordering 
the shores but nevertheless containing typical sea shells. 
The elaborate dental apparatus is such as to show clearly that 
