312 G. E. Beeclier — Reconstruction of a Cretaceous Dinosaur. 



In 1891, the Yale University Museum received the skeleton of a 

 herbivorous dinosaur from the Laramie beds of the Cretaceous in 

 Converse County, Wyoming. The specimen is one of the many 

 treasures in the Marsh collection, and was obtained in the field by' 

 Mr. J. B. Hatcher and party. This skeleton and another apparently 

 belonging to the same species were made the basis of the pictorial 

 restoration of Glaosaurus annectens, as published by the late Profes- 

 sor Marsh. 6 On account of the completeness of the material, and 

 especially because many of the more important bones were in their 

 true position in the rock, the writer decided to direct the prepara- 

 tion of the specimen as a museum exhibit. Most of the work of 

 mounting has been performed in an admirable manner by Mr. Hugh 

 Gibb, preparator in the Geological Department, and to his skill is 

 due the elegance of the finish and the solid strength of the specimen. 



The animal lav on its side in the rock and was somewhat laterally 

 compressed. The preservation was such that the left side was in 

 much better condition than the right. It was therefore decided t<> 

 mount the skeleton in high relief on a slab consisting in part of the 

 original sandstone matrix. The amount of relief shows all four 

 limbs, those on the left side being entirely free. The left side of 

 the entire vertebral column is exposed and the head shows the front, 

 back, top, bottom, and left side, the right only being concealed. 



Owing to the shattered condition of the left femur (making it 

 impracticable to free it from the matrix) and to its being in the 

 rock in its true position with respect to the pelvis, the pose of the 

 animal was determined in laro'e measure by this bone. It is directed 

 forward at such an angle as to demand a running position for 

 bipedal locomotion. An attempt has been made to carry out this 

 idea of rapid motion and to make all parts of the skeleton contribute 

 to the completeness and realism of the general effect. In order to 

 do this there must be the proper balance and the true swing of the 

 living animal. 



It is intended, therefore, that this huge specimen, as now mounted, 

 should convey to the observer the impression of the rapid rush of a 

 Mesozoic brute. The head is thrown up and turned outward. The 

 jaws are slightly separated. The fore arms are balancing the sway 

 of the shoulders. The left hind leg is at the end of the forward 

 stride and bears the entire weight of the animal. The right foot 

 has completed a step and has just left the ground preparatory to the 

 forward swing. The ponderous and powerful tail is lifted free and 

 doubly curved so as to balance the weight ami compensate for the 



