NORTH AMERICA AND THEIR VERTEBRATE FAUNA. 6 1 



The Red Beds were followed from their eastern limit in Oklahoma to 

 their final appearance as vertical beds on the eastern side of the Rocky- 

 Mountains, and kept continuously in sight, except where they disappeared 

 beneath the Dakota Cretaceous, in the mesa just east of Las Vegas, and under 

 the Tertiary of the Staked Plains. The last trace of the Permo-Carboniferous 

 was seen on the east side of the Staked Plains, near Spurr, in Dickens County 

 (plate 13, fig. i) ; on the west side all the red beds along the route followed 

 are Triassic (plates ii, 12, 13). At Las Vegas Hot Springs the beds are 

 vertical (plate 12, fig. 3), or nearly so, and the conditions are extremely 

 unfavorable for seeking vertebrate fossils, but after a half-day's careful 

 search a single imperfect tooth of a Triassic dinosaur was found in a bed 

 of conglomerate. This tooth was discovered near the middle of the section 

 and demonstrates that the upper half, or more, of the exposure is Triassic. As 

 the beds below are strikingly similar to the one in which the tooth was found, 

 it is apparent that if any Permo-Carboniferous appears on the side of the 

 mountains it is very thin. I am inclined to the belief that the Permo-Carbon- 

 iferous beds end somewhere beneath the Triassic in eastern New Mexico. 



Schuchert, in his paleogeographic map of the Permian, shows the Guada- 

 lupian region as distinctly separated from the Texas-Oklahoma-Kansas re- 

 gion. Beede believes in the presence of a barrier to marine life, but assumes 

 the continuance of red-bed deposition. "■ Schuchert, quoting Girty, asserts 

 the independence of the Hueconian and Guadalupian faunas and later 

 deposits of the Cordilleran sea.'' Girty says: 



"Through the west, however, these faunas will probably prove to have ex- 

 tended widely. The Hueco will perhaps prove to be the same as the Aubrey forma- 

 tion of northern Arizona." 



Schuchert himself says : " 



"The writer believes that the Aubrey faunas are younger than those of the 

 Hermosa, but still Pennsylvanian, and of a distinct faunal province — that is, of the 

 western Cordilleran basin." 



Schuchert again quotes from Girty: ^ 



"The Mississippian faunas, together with the earlier Pennsylvanian ones, ap- 

 pear to be absent [in the Trans-Pecos region]. The Hueconian fauna is widely dis- 

 tributed over the West, ranging, indeed, into Alaska, while it is even recognizable in 

 Asia and eastern Europe. Most of the occurrences of Carboniferous in the West can 

 be referred to this series, though some of them present more or less distinct fades." 



And again: 



' ' The life of the Guadalupian is quite unlike the faunas of eastern North America, 

 and almost equally unlike most of those of the West . The nearest are probably those 

 of the Salt Range and Himalaya, in India, and the Fusulina Umestone of Palermo." 



These quotations from Schuchert and Girty seem to confirm the author's 

 opinion that the Permo-Carboniferous does not occur on the western side 

 of the Staked Plains, at least in the latitude of Las Vegas, in Texas and 

 eastern New Mexico. 



» Beede, Amer. Jour. Sci., vol. xxx, Aug., 1910, p. 138. ' Loc. cit., p. 574. 



b Schuchert, Paleogeography of North America, p. 573- ' Girty, Jour. Geol., 1909, p. 311. 



5 



