106 THE CEEATOPSIA. 



beneath the surface by its dip of 9 or 10 degrees near the coal mine. The upper portion of it is also exposed on the south 

 side of Bitter Creek Valley, about a mile from the station. All of the Laramie fossils, whether plants, invertebrates, or 

 vertebrates, that have hitherto been described or listed as coming from Black Buttes were obtained from the overlying beds 

 within about 100 feet of the top of this massive sandstone. The original specimen of Agathaumas sylvestris was found about 

 20 feet above it, and the plants that have been described came from the same horizon and from several higher bands up to 

 the bed overlying the principal coal, some 60 or 75 feet higher. The invertebrates from this locality have about the same 

 range. Most of the beds vary considerably in character and thickness within short distances, but the fossiliferous and 

 overlying portions of the section may be described in general terms as a series of variable sandstones, clays, and coal beds 

 exposed in low hills and ridges with a dip of 9 or 10 degrees eastward at the base, but decreasing in the upper portions to 5 

 or 6 degrees, which is about the same as the dip of the overlying Wasatch beds." 



DESCRIPTION BY COPE. 



Cope's original description of the present genus and species is as follows: a 



During the present season F. B. Meek, of Dr. F. V. Hay den's Geological Survey of the Territories, discovered some large 

 bones near Black Buttes station, on the Union Pacific Railroad, 52 miles east of Green River and near the Hallville coal 

 mines. Shortly afterwards I visited the spot with a branch expedition, and commenced excavations with a view to the 

 recovery of the remainder of the animal. The position was discovered to be between the thinner or lower strata of the Bitter 

 Creek series of coal, which at this point, occupy a position of elevation and crop out high on the bluffs. Two strata appear 

 above the sandstone in which the bones occur and one below it. The portion of the skeleton found rested in the midst of 

 vegetable debris, as sticks and stems, and was covered with many beautiful dicotyledonous leaves, which filled the interstices 

 between the bones. The plant bed gradually passed into a shell bed, containing numerous thin dimyaria, and close by some 

 oysters were found. The whole question as to geologic age and aqueous conditions during which these beds were deposited 

 being unsettled, I gave especial attention to the recovery of the bones, with the view of reaching a definite conclusion on 

 these points. 



We succeeded in recovering 16 vertebras, including a perfect sacrum, with dorsals and caudals; both iliac and other 

 pelvic bones, those of one side nearly perfect: some bones of the limbs, ribs, and other parts not determined. 



The vertebra? are large. The dorsals are short, with vertically oval centra and small neural canal. The diapophvses 

 originate, well above the neural canal, diverge upward, and are triangular in section. The neural spine is very much elevated 

 and the arch short antero-posteriorly. The zygapophyses are close together in both directions, those of the same aspect 

 being separated by a narrow keel only. They do not project, but consist of articular surfaces cut into the solid spine. The 

 latter is flat and dilated distally. The articular faces are nearly plane with a slight median prominence. 



The ribs have two articular surfaces, but I found no capitular pit on the dorsal centra. 



Elevation of centrum 7.5 inches; width of same, 5 inches 7.5 lines; length of same, 3 inches 8.5 lines. Total elevation 

 of a dorsal vertebra, 28 inches 3 lines. The sacrum consists of five vertebrae, the anterior centrum not depressed. They 

 give out huge diapophyses which are united by suture. They are themselves united distally in pairs, each pair supporting a 

 longitudinal convex articular face for the ilium. Each pair incloses a perforation with the centra. The first diapophysis 

 goes off from the point of junction of the first and second vertebras, the second from the third only, and is more slender. 

 The total length is 25 inches, and the width 30 inches. Its vertebrae are flat below, with latero-inferior angles. The last 

 centrum gives off a simple diapophysis. 



Another vertebra exhibits a diapophysis as low as the floor of the neural canal and united by coarse suture. Others 

 posterior to the sacrum are more elongate, with slightly compressed centrum and with diapophysis opposite floor of canal 

 and not united by suture. Centra flat below; no chevron bones discoverable. Length of centrum, 4 inches 4 lines; depth 

 of articular face, 4 inches; width of same, 4 inches 3 lines. 



The iliac bone is extended antero-posteriorly. One extremity is thick and rather obtuse, but of little depth. There is 

 a large protuberance above the acetabular sinus. The other extremity is dilated into a flat, thin plate of rather greater length 

 than the stouter extremity. From one of its margins a rod-like element projects. Its total length is about 4 feet, of which 

 the acetabular sinus measures about 8.10 inches. 



A short bone pertaining to the limbs has the articular surfaces at a strong angle to each other, hence the shaft is twisted. 

 It is deeply grooved on one side near the extremity. The other extremity bears a rather flattened hourglass-shaped articular 

 face, and below it on one angle is a crest. The convexity of the surface is not great, and this extremity resembles that of a 

 dinosaurian or crocodilian reptile. Its length is, however, only 8J inches; apparently too small for a humerus, though this 

 is not certain, while it is decidedly too small for a metatarsal of such an animal. 



From the above description it is evident that the animal of Black Buttes is a dinosaurian reptile, the characters of the 

 sacral and iliac bones alone sufficing to demonstrate this point. If the reader will compare the measurements given for species 

 of this group already known he will observe that those of the present animal exceed those yet described from North America. 

 It is possible that if the corresponding parts of Hadrosavrus tripos Cope, or Thespesius occidentalis Leidy, are discovered, 

 they may approach it. 



It is thus conclusively proven that the coal strata of the Bitter Creek Basin of Wyoming Territory, which embraces the 

 greatest area yet discovered, were deposited during the Cretaceous period, and not during the Tertiary, though not long 

 preceding the latter. It appears that the forests that intervene between the swamps of epochs during which the coal was 



a Proc. Am. Philos. Soc, vol. 12, pp. 481- 



