The hind limbs are very long and straight, the fore limbs
relatively short, and the short high arched back and extremely deep
and compressed body served to exaggerate the height and prominence of
the great plates. The surface of these plates, covered with a network
of blood-vessels, shows that they bore a covering of thick horny skin
during life, which probably projected as a ridge beyond their edges
and still further increased their size. The spines of the tail, also,
were probably cased in horn.
This extraordinary animal was a contemporary of the Brontosaurus and
Allosaurus, and its discovery was one of the great achievements of the
late Professor Marsh. The skeletons which he described are mounted in
the Yale and National Museums. Another skeleton was found in the
famous Bone-Cabin Quarry, near Medicine Bow, Wyoming, by the American
Museum Expedition of 1901. This skeleton, at present withdrawn from
lack of space, will be mounted in the Jurassic Dinosaur Hall in the
new wing now under construction.
[Illustration: Fig. 35.--Skull and lower jaw of Armored Dinosaur
_Ankylosaurus_, from Upper Cretacic (Edmonton formation) of
Alberta. Left side view. _After Brown_]
ANKYLOSAURUS.
Related to _Stegosaurus_, equally huge, but very different in
proportions and character of its armor was the Ankylosaurus of the
late Cretacic. This animal, a contemporary of the Tyrannosaurus and
duck-billed dinosaurs was more effectively though less grotesquely
armored than its more ancient relative.
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