. The Ceratopsia. Ceratopsia. 86 THE CERATOPSIA. to a young individual. In this respect this element resembles very closely the same portion of the squamosal in Marsh's type of Sterrholophus flabellatus, founded on a very complete skull of a young individual, and I am inclined to the opinion that the smooth surface of the squamosals and parietals upon which Marsh largely based his generic distinctions was due rather to the immature age of the individual than to generic differences. The supraorbital horns in the type of the present species appear to be attached by suture to their supporting ele
. The Ceratopsia. Ceratopsia. 86 THE CERATOPSIA. to a young individual. In this respect this element resembles very closely the same portion of the squamosal in Marsh's type of Sterrholophus flabellatus, founded on a very complete skull of a young individual, and I am inclined to the opinion that the smooth surface of the squamosals and parietals upon which Marsh largely based his generic distinctions was due rather to the immature age of the individual than to generic differences. The supraorbital horns in the type of the present species appear to be attached by suture to their supporting elements and to have been developed from distinct and separate centers of ossification, much as the horn cores in the giraffe. In other words,they seem to have an origin independent of the other elements of the skull, which serve them simply as supports. In each supraorbital horn core in the present instance there . appears at the base a distinct ridge, well shown in the accompanying fig- ures, entirely encircling the base of the horn and giving the appear- ance of a suture which has not yet been fully obliterated, owing, per- haps, to the somewhat immature age of the individual. This lat- ter condition is further indicated by the somewhat imperfect union of the epoccipitals already re- ferred to. Certain characters j ust referred to in the present skull would seem to suggest that the supraorbital horn cores in the earlier Ceratopsia at least were developed independently of the other cranial elements, while the nasal horn was derived in part also from a distinct center of ossification. ,• The material above described, which forms the type of the pres- ent species, represents an ani- mal of considerable dimensions. Though smaller than any of the Ceratopsia from the Lara- mie of Wyoming, Montana, or Colorado, it was nevertheless decidedly larger than most of those known from the Judith River beds. In the development of the supraorbital horn •cores it shows a very decided advance
Size: 1314px × 1902px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherwashingtongovtprin
