d 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 deposited along the Atlantic coast.

"The bones of the erect specimen are but little 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." (Subsequent discoveries have shown that the
arrangement of the digits made by Marsh and followed in this skeleton
is incorrect. It is the first digit that is absent, and the fifth is
reduced.)

"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
adapted for locomotion in the water. It may also have served to
balance the creature when standing erect on shore. The broad expanded
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 which 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 bor