R. 8. Lull — Dinosaurian Distribution. 17 



Upper Triassic, the possible equivalent of the Rhsetic, being 

 represented in the bone by Nanosaurus, of the Hallopus beds 

 near Canon City, Colorado, described by Marsh as a carnivore, 

 but which v. Huene and Lull (1908, p. 143) have lately 

 referred to this order. This type comes from the Upper Trias 

 or Lower Jura of Colorado and is absolutely unique. 



Williston, in a letter to the author dated Canon City, Colo- 

 rado, July 11, 1909, says : " After a careful study of the locality 

 and region the conclusions I reach are : Nothing more definite 

 as to the age of the Hallopus beds can be said than was given 

 by Marsh. In my opinion they are either uppermost Trias or 

 Lower Jurassic, though possibly of Middle Jurassic age. .No 

 fossils of any kind have ever been found below them in the 

 Canon City region. The type [of Hallopus] was found 

 between 60 and 70 feet above the Red beds, doubtless of 

 Triassic age. The intervening strata are distinctly conformable 

 with the Red beds. All the known Morrison fossils from 

 Canon City are from above the Hallopus horizon, from one to 

 three hundred feet, though numerous fragments of sauropods 

 in the hillside suggest the possibility of less interval between 

 them. There is no persistent red sandstone stratum in the 

 Hallopus horizon. * * * my conclusion is that, until other 

 fossils are. found to fix more definitely their age, it is unwise to 

 assign definitely either Triassic or Jurassic age to them. Jura- 

 Trias will express this uncertainty." 



Impressed upon the rocks of the ^Newark system, the equiva- 

 lent of the Old World Rhsetic, in the Connecticut valley and 

 New Jersey are numerous footprints which Lull (1901, p. 499) 

 has shown to pertain to ornithopod forms, the genus Ano- 

 moepus unquestionably. Two other genera may also belong 

 to the Ornithopoda, Kubrontes of larger size and the aberrant 

 Otozoum, the bipedal tracks of which indicate a foot unlike 

 that of any known- dinosaur. The footprints included under 

 the genus Anommpus show a considerable range in size but 

 are all such as could have been made by forms like Nano- 

 saurus and Ilypsilojphodon. 



England again gives us the only record of Jurassic types, if 

 we eliminate Nanosaurus and the Morrison forms, Campto- 

 saurus prestwichii described as Iguanodon being found in the 

 Kimmeridge clay. The other Jurassic types which have been 

 referred to Camptosaurus Gilmore (1909, pp. 289-292) con- 

 siders as invalid so far as the genus is concerned. The 

 Oxfordian has yielded Cryptodraco (Cryptosaurus) which v. 

 Huene (1909, p. 21) considers as ancestral to Camptosaurus, 

 the central type of this group. 



From the American Morrison are Camptosaurus, and a lesser 

 form Laosaurus and its relative Dryosaurus, which, together 



Am. Jour. Sci.— Fourth Series, Vol. XXIX, No. 169.— January, 1910. 



2 



