CONDITIONS OF FOSSILIZATION 251 



he is not far wrong in his estimate. And it was one of these prizes which 

 was discovered by Mr. Paul Miller, of the University of Chicago Expe- 

 dition of 1909j between the valley of Indian Creek and the Wichita Eiver, 

 about 5 miles west of the Vernon road. A large quantity of small bones 

 weathered out and lying in a small gully led to the detection of a bone 

 bed or ^^quarr/^ that is without equal in the history of the Texas Permian 

 exploration. The clay lying over the mass of bones protruding from the 

 hillside was entirely free from nodular masses, and, with the exception of 

 a few ounces of bone fragments a half mile away, not another indication 

 of a fossil was discovered in the adjacent exposures covering several hun- 

 dred acres. The clay was excavated down to the level of the bones, and 

 tlie bones were then removed in large clay blocks securely bandaged. It 

 was found quite inexpedient to attempt the removal of the bones from 

 tlie matrix in the field. Not only was the thin adherent matrical cover- 

 ing of the bones so perfectly like the clay in appearance that to distin- 

 guish the bones from fragments of the indurated clay when loosened re- 

 el uired the most minute examination, but the interlacing of the numerous 

 skeletons in the mass prohibited the attempt to separate them in the field. 

 Indeed, in the laboratory the only safe way to prevent the loss of small 

 bones and fragments of bones when dissociated is to dissolve the clay 

 in water. As it was, with the inadequate tools at our command near 

 the close of the season, the complete excavation of the bed was not at- 

 tempted, but will be resumed the present season by Mr. Miller, when it 

 is confidently expected that much additional material will be secured. 



The skeletons lay in a narrow deposit about 5 feet in width and of 

 unknown extent throughout a thickness of about 2 feet, and apparently 

 on a sloping horizon. They are almost invariably found lying on the 

 ventral side, and for the most part with the members undisturbed, save 

 til at in some cases the phalanges of the feet are more or less scattered 

 about, and the tail or whole limbs may be dislodged. Many of the bones 

 have a very thin layer of cemented clay covering them; others are more 

 or less cemented together in nodular masses. It is very evident from the 

 character of the deposits and the position of the bones that the skeletons 

 had suffered but little disturbance after death; that the creatures had 

 for the most part died peacefully in a stagnant, perennial pool of water, 

 successive generations piled upon each other in layers. 



I estimate that, so far, there is evidence of at least 50 or 60 skeletons 

 in the deposit. From the loose material recovered from the surface I 

 count over 50 femora, nearly as many humeri and corresponding girdles, 

 with large quantities of the vertebras. In the blocks containing the 

 thickly aggregated skeletons secured, there are probably representatives 



