330 R. S. LULL SAUROPODA AND STEGOSAURIA OF THE MORRISON 



ventured. The small Oruithopod genus is described as similar to the 

 American Laomurus and the English Ilypdlophodon. Laosaurus is a 

 well defined genus from the ]\rorris()n and Potomac formations, Avhile 

 ni/psilophodo7i is a persistently primitive type from the English Wealden, 

 llie only Predentate dinosaur with teeth in the premaxillary hone. 



Stratigraphically I can find no record of the level wherein (li(/anl<)- 

 smiriis was found, as Fraas did nut clearly differentiate tlic three dinosaur 

 beds, but speaks of tlic dinosaur liorizou as though theie wen.' hut one. 

 Both species of Braclniomiinis. tlic Stegosaur (Hiarry and the hirger/iF 

 the two Dicrajosaiirs, are in the middle l^eds, while JHrid'/jsaurtis salUcri 

 is from the upper one. This places the Brachiosaurs, which are the 

 dinosaurs of greatest present utility for comparison with the American 

 types, in the strata which can be most surely dated, as they lie between 

 the two marine horizons, and thus both the upper and lower limit can 

 be fixed. 



Unfortunately at this writing J eau not obtain a report on the marine 

 invertebrates of the Tendaguru, ahhough such luive Ijeen published by 

 Hennig and others. The reviews of two of these pa])eis in the Geo- 

 logisches Zentralblall (.June 1. 1!I14) contain certain inconsistencies 

 wliich are difficult to reconcile without reference to the original works. 

 The evidence, however, subject to future correction, seems to be as 

 follows : 



1. Trigonia scliwarzi zone (Lower-Middle Neocomian). 



I. Upper dinosaui' horizon — upper Tithonian to lowest Xco- 

 comian; somewhat of Wealden — Wealden plants. 

 "2. Trigonia smeei zone — typical Tithonian — in ])art uppermost Tviui- 

 meridgian. 



II. Middle dinosaur horizon — Lower Kimmeridgian. 

 3. Nerinpa zone — Oxfordian. 



III. Lower dinosaur horizcni — J^ower Uxfordian to Ivelloway. 



The upper dinosaur beds seemingly belong faunally. florally. and as 

 regards facies to the Xeocomian or Wealden. 



If this evidence be correctly interpreted, it places the majority of the 

 dinosaurs, the horizon of which is known, between Upper Jurassic marine 

 beds and those of the Comanchian, while the highly specialized Dirrwo- 

 saurus sattleri is of still younger Comanchian time. 



WEALDEN 



Sawopoda. — England and northern France particulaily liave produced 

 a long generic list of Sauropod dinosaurs, most of which are founded on 



