Dinosaurs, with Special Reference to the American Museum Collections

DINOSAURS (

Dinosaurs,-Trachodo

thopoda; Famil

ought about various changes in the race, not so much in general proportions as in altering the form and relations of various bones of skull and skeleton and perfecting

two fine mounted skeletons of the largest size. There is also on exhibition a panel mount of a nearly related genus, Saurolophus the skeleton lying as it was found in the rock, and a fine skeleton of a third genus Corythosaurus with the skin partly preserved on both sides of the crushed and flattened body stands beside it. In the Tyrannosaurus group when completed will

ACHODO

p is by Mr. Barnum Brown and first appeared in

erized the period, when one is startled by the approach of a carnivorous dinosaur, Tyrannosaurus, their enemy, and rises on tiptoe to look over the surrounding plants and determine the direction from which it is coming. The other Trachodon, unaware of dan

on in the American Museum. Height of

commonly taken by the creatures during life. Mechanical and anatomical considerations, especially the long straight shafts of the leg bones, indicate that dinos

n New Jersey, Mississippi and Alabama, but more commonly in Wyoming, Montana, and the Dakotas. A suggestion of the great antiquity of these specimens is giv

he 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

he 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

ed to form a broad duck-like bill which during life was covered with a horny sheath, as in birds and turtles. Each jaw is provided wi

mbers on the shores of the Galapagos Islands off the coast of Chile. They swim out to sea in shoals and feed exclusively on seaweed which grows on the bottom at some distance from shore. The animal swims with perfe

red as in Ankylosaurus. Trachodon was not provided with horns, spines or plated armor, but it was sufficiently protected from carnivorous land forms by being able to enter and remain in the water. Its skin was covered with small raised scales, pentagonal in form on the body and tail, where they were lar

ern California. Palm leaves resembling the palmetto of Florida are frequently found in the same rocks with these skeletons. Here occur also such, at present, widely separated trees as the gingko now native of China, and the Sequoi

r Os

nder supervision of Professor Osborn, embodies the latest evidence as to the structure and charact

ch the skeletons stand. In the rivers and bayous of that remote period there also lived many kinds of Unios or fresh-water clams, and other shells, the casts of which are frequently found with Trachod

anchman, Mr. Oscar Hunter, while riding through the bad lands with a companion in 1904. The specimen was partly exposed, with backbone and ribs united in position. The parts that were weathered out are much lighter in color than the other bones. Their large size caused some discussion between the ranchmen and to settle the question, Mr. Hunter dismounted and kicked off all the tops of the vertebrae and rib-heads above ground, thereby proving

r Os

of a Trachodon preserving the skin imp

OSAUR "

of us. But this "dinosaur mummy" sprawling on his back and covered with shrunken skin-a real specimen, not restored in any part-brings home the reality of this ancient world even as the mummy of an ancien

st 1908, by the veteran fossil hunter Charles H. Sternberg of Kansas. It is a large herbivorous dinosaur of the closing pe

vering of these dinosaurs was gained. It appears probable that in a number of cases these priceless skin impressions were mostly destroyed in removing the fossil specimens from their surroundings because the explorers were not expecting to find an

ng time, perhaps upon a broad sand flat of a stream in the low-water stage; the muscles and viscera thus became completely dehydrated, or desiccated by the action of the sun, the epidermis shrank around the limbs, was tightly drawn down along all the bony surfaces, and became hardened and leathery, on the abdominal surfaces the epidermis was certainly drawn within the body cavity, while it was thrown into creases and folds along the sides of the body owing to the shrinkage of the tissues within. At the termination of a possible low-water season during which these processes of desiccation took place, the 'mummy' may have b

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 sid

r Os

Mummy. Detail of skin

have been left by horny scutes or scales, not overlapping like the scales on th

a), for comparison of surface with skin

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 restoratio

e beak, has long been considered in connection with the theory of aquatic habitat. The conversion of

y doubles our previous insight into the habits a

ds. Saurolophus has a high bony spine rising from the top of the skull; in Corythosaurus there is a thin high crest like the crown of a cassowary on top of the skull, and the muzzle is short and small giving a very peculiar aspect to the head. Complete skeletons of these t

er

Saurolophus, from Upp

and southward along the Atlantic coast. A partial skeleton was described many years ago by Leidy under the name of Hadrosaurus and restored and mounted in the museum of the Philadelphia Ac

TNO

oup." Amer. Mus. Jour. Vol. viii, pp.

saur Mummy" Amer. Mus. Jour. Vol. x

ether this was really the c