TRIASSIC PORTION OF SHINARUMP GROUP 113 



It seems to be assumed by Ward, as by others, that the occurrence 

 of fossil wood throughout his Shinarump formation is an indication 

 of its unity. But until these woods have been studied the correctness 

 of that view is open to question. The presence of rounded pebbles 

 of silicified wood in the Shinarump conglomerate has been asserted 

 by several observers, and, if true, this fact alone must cause critical 

 comparison of the fossil trunks occurring above and below this horizon. 



The only tree trunks found by Ward in vertical position, as though 

 in the place of growth, were in the Leroux beds very near the locality 

 at which the best vertebrate remains were found, east of Tanner's 

 crossing of the Little Colorado. 



Vertebrate remains were found by Ward and Brown only in the 

 Leroux beds and mostly in their lower portion. The principal 

 localities from which they were collected by Brown for the National 

 Museum are a few miles east or north of Tanner's Crossing, but they 

 were noted at other places, including the "petrified forest." The 

 material has been examined and partially described by Lucas (17 

 and 18), the forms identified by him being the following: 



Two belodont crocodiles, Episcoposaurus sp. ? Cope, and Hete- 

 rodontosuchus ganei, Lucas, the type of which came from the San 

 Juan Valley, Utah; Metoposaurus fraasi, Lucas, n. sp., Placerias 

 hesternus, Lucas, n. sp., and Palaeoctonus sp. ? Cope. 



This fauna is in Lucas' opinion a distinctly upper Triassic one. 

 He remarks that: 



Aside from the interest attached to the finding of this new species (of Meto- 

 posaurus) is the more important fact pointed out by Dr. Fraas (personally) that 

 the genus Metoposaurus is characteristic of the Keuper of Europe, and that we 

 have in these Triassic beds of Arizona, Utah, and Wyoming the same combination 

 of belodont and labyrinthodont as in the Keuper (18, p. 195). 



He might have added that the fauna is clearly present in the 

 Dolores formation of Colorado. 



Ward states that Brown found "a small number of shells and a 

 few other invertebrates" with the vertebrate remains, but since their 

 diagnostic value was questioned by Ward, they do not seem to have 

 been submitted to a specialist for examination. Mr. T. W. Stanton 

 informs me that the only invertebrates now in Brown's collection 

 in the National Museum are Paleozoic brachiopods, corals, etc., in 



