XI. rilK JURASSIC DINOSAUR DEPOSITS NEAR CANYON 

 CITY, COLORADO. 



By J. B. Hatcher. 



Notwithstanding the great wealth of certain, indeed of several, of 

 our Mezozoic horizons in dinosaurian remains and the exceptional vigor 

 with which the bringing together and study of dinosaur bones have 

 been pursued for the last quarter of a century in this country by Marsh, 

 Cope, Baur, Osborn, Williston and others, and for an even longer 

 period, though under much less favorable conditions, by British and 

 European paleontologists, yet we are still ignorant of the complete 

 osteology of all but a few of the many proposed genera of dinosaurs, 

 while of the phylogeny of the various genera and species of the differ- 

 ent families we know absolutely nothing. This is the more remarkable 

 considering the progress that has been made in mammalian paleonto- 

 logy, where in many families, as for instance the horses, camels, and 

 titanotheres, nearly every step in their development has been traced 

 and can be pointed out with as much precision as can the different 

 stages in the perfection of the modern steam engine, electric motor, 

 or other mechanical device wherein the forces of nature have been 

 made to serve the uses of man. This disparity in the progress of 

 these two closely related branches of vertebrate paleontology has not 

 been due to a lack of interest in dinosaur remains as such, for many of 

 these animals by reason of their remarkable size and grotesque form 

 have from their earliest discovery inspired almost universal interest. 

 The difficulty in placing and keeping our knowledge of dinosaurs 

 abreast with that of mammals has been due rather to the vastly greater 

 difficulties encountered in bringing together sufficiently complete col- 

 lections from the various localities and horizons to permit of a com- 

 parative study of the different forms from each. These difficulties 

 arise from the great size of the individual animal in many genera and 

 species, from the scarcity of dinosaur remains in many horizons and 

 from the difficult nature and great expense of the work necessary for 

 collecting dinosaurs. Moreover dinosaur remains have as a rule been 

 found only in essentially one horizon in the same formation at any 

 given locality, and when found at different and widely separated locali- 



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