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DINOSAURS

Chapter 9:

THE BEAKED DINOSAURS (Concluded.)

D. The Horned Dinosaurs, Triceratops, Etc.

Sub-Order Ceratopsia.


In 1887 Professor Marsh published a brief notice of what he supposed to be a fossil bison horn found near Denver, Colorado. Two years later the explorations of the lamented John B. Hatcher in Wyoming and Montana resulted in the unexpected discovery that this horn belonged not to a bison but to a gigantic horned reptile, and that it belonged not in the geological yesterday as at first thought, but in the far back Cretacic, millions of years ago. For Mr. Hatcher found complete skulls, and later secured skeletons, clearly of the Dinosaurian group, but representing a race of dinosaurs whose existence, or at least their extraordinary character, had been quite unsuspected. It appeared indeed that certain teeth and skeleton bones previously discovered by Professor Cope were related to this new type of dinosaur, but the fragments known to the Philadelphia professor gave him no idea of what the animal was like, although with his usual acumen he had discerned that they differed from any animal known to science and registered them as new under the names of Agathaumas 1873 and Monoclonius 1876. Professor Marsh re-named his supposed bison "Ceratops" (i.e. "horned face") and gave to the closely related skulls discovered by Mr. Hatcher the name of Triceratops (i.e. "three horned face"), while to the whole group he gave the name of Ceratopsia.
Fig. 37.: Skulls of Horned Dinosaurs.

Fig. 37.—Skulls of Horned Dinosaurs. The lower row, Ceratops, Styracosaurus, Monoclonius, are from the Middle Cretacic (Belly River formation) of Alberta; Anchiceratops is from the Upper Cretacic (Edmonton formation) of Alberta; Triceratops and Torosaurus from the uppermost Cretacic (Lance formation) of Wyoming.

These were the first of a long series of discoveries which through scientific and popular descriptions have made the Horned Dinosaurs familiar to the world. Most of them are still very imperfectly known, and of their evolution and earlier history we know very little as yet. But we can form a fairly correct idea of their general appearance and habits and of the part they played in the world of the late Cretacic. So far as known they were limited to North America. The most striking feature of the Horned Dinosaurs is the gigantic skull, armed with a pair of horns over the orbits and a median horn on the nasal bones in front, and with a great bony crest projecting at the back and sides. In some species the skull with its bony frill attains a length of seven or even eight feet and about three feet width; the usual length is five or six feet and the width about three. In the best known genus, Triceratops, the paired horns are long and stout and the front horn quite short or almost absent, while in Monoclonius these proportions are reversed, the front horn being long while the paired horns are rudimentary.

The teeth are in a single row but are broadened out into a wide grinding surface. The animal was quadrupedal, with short massive limbs and rounded elephantine feet tipped with hoofs, three in the hind foot, four in the fore foot, a short massive tail that could hardly reach the ground, a short broad-barrelled body and a short neck completely hidden on top and sides by the overhanging bony frill of the skull. In many respects these animals are suggestive far more than any other dinosaurs, of the great quadrupeds of Tertiary and modern times, rhinoceroses, hippopotami, titanotheres and elephants, as in the horns they suggest the bison. For this reason although less gigantic than the Brontosaurus or Tyrannosaurus, less grotesque perhaps, than the Stegosaurus, they are more interesting than any other dinosaurs. While thus departing far from the earlier type of the beaked dinosaurs (the Iguanodonts) they are evidently descended from them.

Fig. 38.: Skull of Triceratops from the Lance

Fig. 38.—Skull of Triceratops from the Lance formation in Wyoming, one-eighteenth natural size. The length of the horns is 2 feet, 9½ inches. The rostral bone or beak, and the lower jaw, are lacking; in the illustration on the cover they have been restored in outline. This fine skull was discovered by George M. Sternberg, and purchased for the Museum by Mr. Charles Lanier in 1909.


TRICERATOPS.

This is the best known of the Horned Dinosaurs, as various skulls and partial skeletons have been found from which it has been possible to reconstruct the entire animal. There is a mounted skeleton in the National Museum, another will shortly be mounted in the American Museum, and there are skulls in several American and European museums.

Triceratops exceeded the largest rhinoceroses in bulk, equalling a fairly large elephant, but with much shorter legs. The great horns over the eyes projected forward or partly upward; in one of our skulls they are 33½ inches long. During life they were probably covered with horn increasing the length by six inches or perhaps a foot. The ball-like condyle for articulation of the neck lies far underneath, at the base of the frill, almost in the middle of the skull.

Fig. 39.: Skull of Monoclonius, a horned dinosaur

Fig. 39.—Skull of Monoclonius, a horned dinosaur from the Cretacic (Belly River formation) of Alberta. One-fifteenth natural size. The horns over the eyes are rudimentary, and the nasal horn large, reversing the proportions in Triceratops.

Monoclonius, Ceratops, etc. The Triceratops and another equally gigantic Horned Dinosaur, Torosaurus, were the last survivors of their race. In somewhat older formations of Cretacic age are found remains of smaller kinds, some of them ancestors of these latest survivors, others collaterally related. None of these have the bony frill completely roofing over the neck as it does in Triceratops. There is always a central spine projecting backwards and widening out at the top to the bony margin of the frill which sweeps around on each side to join bony plates that project from the sides of the skull top. This encloses an open space or "fenestra," so that the neck was not completely protected above. Sometimes the margin of the frill is plain, at other times it carries a number of great spikes, like a gigantic Horned Lizard (Phrynosoma

Fig. 40.: Outline sketch restoration of Triceratops,

Fig. 40.—Outline sketch restoration of Triceratops, from the mounted skeleton in the National Museum.

In Ceratops the horns over the eyes are large and the nasal horn small. In Monoclonius the nasal horn is large and those over the eyes are rudimentary. The great variety of species that has been found in recent years shows that these Horned Dinosaurs were a numerous and varied race of which as yet we know only a few. Of their evolution we have little direct knowledge, but probably they are descended from the Iguanodonts and Camptosaurs of the Comanchic, and their quadrupedal gait, huge heads, short tails and other peculiarities are secondary specializations, their ancestors being bipedal, long-tailed, small headed and hornless.

The fine skulls of Triceratops, Monoclonius, Ceratops and Anchiceratops in the Museum collections illustrate the variety of these remarkable animals. Complete skeletons of the first two genera are being prepared for mounting and exhibition.



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