380 B. BROWN CRETACEOUS-EOCENE CORRELATION IN NEW MEXICO 



The large eamivorous dinosaurs are smaller than Tyrannosaurus of 

 the Lance and may be compared with AJbertosaurus of the Edmonton or 

 Deinodon of the Judith River. 



The Trachodont dinosaurs furnish the most satisfactory evidence for 

 the correlation of these beds. The genus Trachodon, which represents 

 the family in the Lance formation, is not known here, but a primitive 

 genus, Kritosaurus, of extraordinary skull development, described from 

 this formation, is common. 



Recently Mr. Lawrence M. Lambe, Ottawa Xaturalist, volume xxxvii, 

 number 11, Februarj^ 1911, described a perfect Trachodont skull from 

 the Belly River beds of Canada. In all respects, including the remark- 

 able development of the nasals, premaxillaries and predentar}' and the 

 reduction of the orbital portion of the frontal, it agrees with the type of 

 Kritosaurus, and there is no doubt of its generic identity-. 



A single species of turtle, Thescehis rapiens Hay, is not knowTi else- 

 where, though a closely related species, T. insiliens, is described from the 

 base of the Lance. 



Li vertebrates are as yet unknown and the flora, represented by numer- 

 ous fossil trees, has not been determined. 



The vertebrate fauna is distinctly older than that of the Lance. I 

 have expressed the opinion that it was comparable to the Edmonton, but 

 from the recent discovery of Kritosaurus in the Belly River formation 

 and the primitive structure of the contemporary dinosaurs the Ojo Alamo 

 beds appear to be synchronous with the Judith (Belly River) formation. 



The vertebrate fauna now known is as follows : 



Kritosaurus napajovius Brown Crocodilia 



f ilonoclonius sp. Thescehis rapiens Hay 



.' Dienodon sp. Lepisosteus sp. 



Conclusion 



Briefly, in conclusion there is no doubt that the Hell Creek beds were 

 synchronous with the ''Lance," and little doubt that the Belly River and 

 Ojo Alamo beds should be correlated with the Judith River. The Ed- 

 monton is intermediate in age between the Judith River. and the Lance. 



A comparison of the reptilian faunae shows an uninterrupted succes- 

 sion of genera from the Judith River through to the close of the Lance. 

 In some cases genera pass through without any marked change. They 

 show those changes brought about through a lapse of time, but there is 

 no evidence of any great migration changes which would be apparent as a 

 result of any great diastrophic movement. 



