Monoclonias, a Cretaceous Horned Dinosaur 



THE FIRST COMPLETE SKELETON OF ITS KIND KNOWN 

 Bv B A R N U M BROWN 



FEW animals have been more dis- 

 cussed than the Ceratopsia, the 

 horned dinosaiirs^ and none has 

 so stimulated the imagination of the 

 observer to speculate on scenes of pre- 

 historic times. Incomplete skeletons, 

 chiefly skulls, have long been known, 

 yet previous to the American Museum 

 expeditions into Canada several im- 

 portant parts of the anatomy, such as 

 the structure of the feet and length of 

 the tail, remained problematical. 



Some of the Ceratopsia were large, 

 others were small, but in all the skull 

 was disproportionately large compared 

 with other dinosaurs of equal bulk. 

 With gigantic head, horns above the 

 eyes and nose, a beak like a turtle's, and 

 double-rooted teeth, they present char- 

 acters unique among reptiles, living or 

 extinct. 



The American Museum expedition of 

 1914 was fortunate in finding a skele- 

 ton of one of the earliest known mem- 

 bers of the family, a Monoclonius, 

 complete in all details from the tip of 

 the nose to the end of the tail, with 

 most of the bones articulated excepting 

 a part of the feet that had weathered 

 out of the bank. The skeleton was 

 found on Sand Creek, a tributary of the 

 Red Deer River, twelve miles below 

 Steveville, in rocks of the Belly River 

 Cretaceous age, and gives for the first 

 time a knowledge of the complete anat- 

 omy of any member of the family Cera- 

 topsia. This skeleton, recently placed 

 on view in the dinosaur hall of the 

 American Museum, has been mounted 

 practically as found, the vertebral col- 

 umn, pelvis, femora and parts of the 

 feet beins: chiseled out in relief from 



the original rock. Those parts of the 

 front feet that were scattered have been 

 assembled, after another specimen in 

 which they are preserved in position. 



In life this animal was about seven- 

 teen feet long from the tip of the tail 

 to the end of the nose, and when stand- 

 ing erect would have measured a little 

 more than six feet in height. It was 

 remarkably short-bodied and walked on 

 all four feet with the front legs bowed 

 outward. On the front feet there were 

 five toes, the three inner ones bearing 

 small hoofs, and on the hind feet four 

 functional toes, each bearing a hoof, 

 and a rudimentary fifth toe. 



Its most striking feature is the enor- 

 mous skull, five feet in length, with a 

 scalloped frill extending over the neck, 

 a rhinoceros-like horn above the nose 

 and a rudimentary horn above each eye, 

 and a beak like a turtle's, sheathed in 

 horn and doubtless used for clipping 

 the leafy foliage on which it browsed. 

 Back of the beak there are rows of dou- 

 ble-rooted teeth. Its brain of low de- 

 velopment was exceedingly small and 

 the comparatively small eye contained 

 a bony ring of plates like those of an 

 owl, which were doubtless a develop- 

 ment for the adjustment of light, 

 probably enabling the animal to see at 

 night as clearly as in the day. The tail, 

 though fairly long, was weakly devel- 

 oped and did not function as a bal- 

 ancing or propelling organ. Above 

 the pelvis a series of bony rods is pre- 

 served, the contracted portions of some 

 of the stronger back muscles. 



In another specimen of Monoclonius 

 a part of the epidermis impression is 

 preserved and we now know that the 



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