THE POSE AND LOCOMOTION OF DIPLODOCUS 15 



The convergence of the femora is rare even among the mammals. 

 If Professor Osborn is right the hind legs of Tyrannosaurus had 

 attained the human stage in the respect mentioned. 



Another potent reason for believing that the dinosaurs just named, 

 together with Iguanodon and Trachodon, walked with a wide tread is 

 found in the form of the body. In mammals the abdomen is usually 

 contracted posteriorly, so that between the thighs it is shallow, per- 

 mitting the femora to remain parallel with each other or even to con- 

 verge. Therefore, in walking, the feet are placed near or on the line 

 of direction. In the birds the baggy abdomen descends between the 

 thighs and spreads these, thus requiring the convergence of the long 

 lower segments to bring the feet together. The kangaroos have the 

 abdomen much like that of the birds; and in them the thighs are found 

 to diverge toward the knees, but the long tibiae permit the feet to be 

 placed close to each other in standing and leaping. In Allosaurus 

 and Iguanodon the belly came down nearly to the knees and passed 

 backward between the thighs into the tremendous tail. It must be 

 that the knees were much farther apart than the upper ends of the 

 femora were and that the tread was wide. The writer is further of 

 the opinion that in the bipedal dinosaurs the femora were directed 

 more strongly forward than they are usually placed in restorations, 

 although not so much so as in birds. This position would tend to 

 reduce the height of the reptiles and would make the thighs more 

 divergent. 



In a paper published by Mr. William H. Ballou (Century Mag., 

 Iv, 1897, pp. 15-23), but the facts and suggestions of which were 

 furnished by Professor E. D. Cope, there is a figure representing two 

 individuals of Hadrosaurus (Trachodon} mirabilis. One of these 

 is on the shore, resting on its hind legs and haunches, the other is 

 standing and feeding in the water. By examining these restorations, 

 made by Mr. Charles R. Knight, one may judge regarding the proba- 

 bility that these reptiles could leave a straight row of tracks behind 

 them. 



Mr. S. H. Beckles 9 has described and figured some series of large 

 footprints found in the Wealden near Hastings, England. These 

 have been identified by Dollo (Bull. Mus. roy. d'Hist. nat. Belgique, 



9 Quart. Jour. Geol. Soc., x, 1854, 456, pi. xix. 



