But in the present stage of discovery it would be rash to conclude that they were surely limited to the regions where they have been discovered.

It is not wholly clear as yet whether the Dinosaurian fauna that flourished at the end of the Jurassic in the north survived to the Upper Cretacic in the southern continents, but present evidence points that way, and indicates that the girdle of ocean which during the Cretacic depression encircled the northern world, formed a barrier which the Cretacic dinosaurian fauna never succeeded in crossing.
The earlier groups of Beaked Dinosaurs are found in both Europe and America, and in the Cretacic the Duck-billed and Armored groups are represented in both regions.

The Horned Dinosaurs, however, are known with certainty only from North America.
While most of the important fossil specimens in this country have been found in the West, more fragmentary remains have been found on the Atlantic sea-board, and it is probable that they ranged all over the intervening region, wherever they found an environment suited to their particular needs..