no. 1648. CERTAIN CARNIVOROUS DINOSAURS— HAY. 357 



Whether or not Osborn's genus Albertosaurus will prove to be well 

 founded only future discoveries can decide. The Edmonton beds are 

 considerably younger than the Judith River. In the interval that 

 elapsed, the genera of dinosaurs may have wholly changed; but we 

 are not certain of this. That Dryptosaurus, an Upper Cretaceous 

 genus, the type of which was found in New Jersey, may have existed 

 in the nearly contemporaneous Judith River epoch and region is 

 wholly probable. Trachodon is believed by paleontologists to include 

 species from the Upper Cretaceous of New Jersey, the Judith River 

 beds of Montana, and the Ceratops beds of Wyoming. Ornithomim us 

 appears to have continued from the Eagle epoch, older still than the 

 Judith River, and from the Judith River epoch itself, to the Edmon- 

 ton/' The type of the genus 0. velox was found in the Denver beds. c 

 Even many species of vertebrates of the Ceratops beds are as yet 

 indistinguishable from those of the Judith River, as noted especially 

 by Williston/* 



It seems likely that Osborn has laid greater emphasis on the prob- 

 able generic distinctness of the dinosaurs from the Upper Cretaceous 

 of New Jersey, the Belly River, the Judith River, and the Edmonton 

 beds respectively, because of his view that the Belly River beds do 

 not belong to the Upper Cretaceous, but to a much lower, though as 

 yet undefined, horizon. c 



Osborn's definition of Dryptosaurus does not seem to exclude from 

 that genus the Judith River dentary described by Cope. In both, 

 some of the anterior mandibular teeth had the long diameter of the 

 section at the base of the crown directed transversely to the axis of 

 the jaw. Furthermore, in case the species incrassatus does not be- 

 long to Dryptosaurus, the establishment of a new genus for its re- 

 ception appears to be required. In any case, Osborn's mild reproach 

 that Lambe had referred the Edmonton skulls to a New Jersey genus 

 loses its force. To say that Lambe had referred those skulls to a 

 Judith River species is incorrect, as has been shown above. 



In Albertosaurus sarcophagus a tooth that may be regarded as the 

 first incisor has, according to Lambe's description, the hinder face 

 fiat, so that the cross section is D-shaped, while the corresponding 

 tooth of Dryptosaurus incrassatus has the anterior cutting edge 

 brought far around toward the inner side of the tooth, thus repre- 

 senting a stage somewhat more primitive than that of Albertosaurus 

 sarcophagus. The species may therefore be generically distinct. As 



Hatcher, Bull. U. S. Geol. Surv., No. 257, p. ST. 



6 Lambe, Contrib. Canart. Palaeont., Ill, Pt. 12. 1902, p. 53. 



c Cross, Monogr. U. S. Geol Surv., XXVII, p. 227. 



d Science, XVI, 1902, p. 952. 



e Contrib. Canad. Pakeont., Ill, Pt. 2, pp. 7-19. 



