2 MEMOIRS OF THE CARNEGIE MUSEUM 
the exceptional energy with which a few institutions are increasing their collections 
our knowledge of the structure and relations of a considerable number of known 
dinosaurian genera has been materially increased during the past few years, while 
occasional discoveries of entirely new forms have been announced. 
It appears somewhat remarkable however that a Sauropod dinosaur of such 
gigantic size and showing such distinctive generic characters as does Haplocantho- 
saurus should have been discovered so recently at the exact locality, near Canyon 
City, Colorado, so long worked and rendered classic by the researches of the late 
Professor Othniel Charles Marsh. This discovery may be taken as an indication not 
only of the great wealth of this particular locality in the remains of the Dinosauria 
but of the great diversity that existed in the reptilian life of this region in Jurassic 
times. For since this single bone quarry, restricted in area to a few hundred square 
feet and with the bone-bearing horizon not more than three feet thick vertically, has 
already produced representatives of at least a dozen genera and species and twice or 
thrice that number of individual skeletons it would seem difficult to overestimate the 
wealth of the reptilian fauna of this region in Jurassic times or to exaggerate the 
total number of genera and species that must have existed throughout the period of 
time required for the deposition of the several hundred feet of sandstones and shales 
that here constitute that formation and imbedded within which we may still hope 
to find remains of additional genera and species pertaining to that peculiar but long 
since extinct group, the Dinosauria. 
For the material upon which the present paper is based we are indebted first 
of ali to the generosity of Mr. Andrew Carnegie whose munificence made it 
possible to carry on the excavations necessary for its recovery. To the skill, 
energy and patience however of Mr. W. H. Utterback we are directly indebted 
for its recovery from the hard, almost granitic sandstones in which the bones 
lay buried beneath many feet of other sandstones and shales only a little less refrac- 
tory than those actually containing the fossils. After these superincumbent sand- 
stones and shales had been removed over a considerable area the actual and more 
difficult work of developing and recovering the fossil bones was begun. These, as 
has been stated above, lay buried in a thick stratum of heavily bedded and hard 
sandstone. Not only was this sandstone for the most part extremely hard but it 
was also considerably fractured in such manner as greatly to increase the difficulty 
encountered in taking up the bones in a proper manner. All difficulties were how- 
ever met and overcome by Mr. Utterback with commendable patience and inge- 
nuity, and the different blocks were received at the paleontological laboratory of the 
museum with all the vertebree and other bones in each block still in their original 
