374 B. BROWN CRETACEOUS-EOCENE CORRELATION IN NEW MEXICO 



Dinosaurs are found in great numbers from near the top to the bottom 

 of the beds, and the same species occur throughout the formation. 

 The remains occur as individual skeletons and partial skeletons, but are 

 frequently massed together" in great numbers as separate bones and 

 partial skeletons. The bones are silicified and frequently they are filled 

 T^-ith calcite. 



The vertebrate fauna is distinct from that of the Lance and few species 

 are common to the two formations. Most of the Edmonton genera are 

 structurally more primitive than those of the Lance and several genera 

 not found in tlic Lance are common to the Judith Eiver. The faunal 

 facies, as a whole, is intermediate, but closer to that of the Judith Eiver 

 formation than to the Lance. 



Trachodonts are most numerous of all the dinosaurs in this forma- 

 tion. All are papillate-toothed species. Three well defined genera — 

 Trachodon, Saurolophus, and Hijpacrosaurus — are known. Of these 

 Trachodon ranges from the Belly Eiver l)eds through the Edmonton 

 and to the close of the Lance, but the Lance species, T. mirahilis and T. 

 antiectetiSj have not been recorded. Hypacrosauriis occurs in the Belly 

 Eiver and Saurolophus, or a closely related genus, occurs there also. 



Ceratopsians are comparatively rare and are represented by a large 

 form of primitive skull structure and a small aberrant form, neither 

 of which has been described. The cliaracteristic genus, Triceratops, and 

 its less abundant contemporary, Torosaurus of the Lance, do not occur 

 in the Edmonton. 



Armored dinosaurs are somewhat more numerous than the Ceratopsia. 

 The Lance genus and species Anki/losauj'us magniventris occurs in this 

 formation and A. tutus is found in the Belly Eiver. An allied genus, 

 not yet described, is common to this formation and to the Belly Eiver. 

 but does not occur in the Ijance. PaUroscinctis, another related genus, 

 occurs in the Belly Eiver and in the Lance, but has not been recorded 

 in the Edmonton. 



Carnivorous dinosaurs are as numerous as the armored forms. Tyran- 

 nosaurus of the Lance does not occur, but a common form about one 

 half as large and ancestral to it is Albertosaurus sarcophagus. Orni- 

 thomimus alius is a Belly Eiver species which- occurs here and has also 

 been noted in the Lance. 



The dinosaur fauna forms a series of successive genera, the phyletic 

 relationship of which is determined by the evolutionary development of 

 skeletal parts, and there is no break in this series from its first appear- 

 ance low down in the Cretaceous to the final disappearance of the entin; 

 group in what we propose to call the close of the Cretaceous. 



