1905.] ON THE SUPPOSED CLAVICLE OF DIPLODOCUS. 289 



9. Remarks on the supposed Clavicle of the Saiiropodous 

 Dinosaur Diplodocus. Bj Francis, Baron Nopcsa, 

 Ph.D.* 



[Received June 6, 1905.] 

 (Text-figures 46-49.) 



It is still uncertain whether the extinct Dinosauria possessed 

 clavicles. 



Considering the close relationship existing between these 

 reptiles, the Rhynchocephalians, Parasuchians, and Birds — this 

 last relationship being shown by the continuous tendency of 

 Dinosaurs to specialize on most different occasions in bird-like 

 manner — one is at first naturally induced to believe that in 

 Dinosaurs clavicles were present ; but, as a matter of fact, bone 

 after bone suj^posed to represent this element has had to be 

 removed from this position. 



Hitherto only the family Ornithopodidee is known to possess, 

 in addition to scapula and coracoid, a curious further element in 

 the shouldei'-girdle, which was called clavicula, but may quite as 

 well form only a pai't of the sternum (this double element being 

 in one case united in the middle by bony matter). JSTo other 

 Saurischian or Orthopodous Dinosaur shows a clavicular ossi- 

 fication. It is true that in the Sauropoda, besides scapula and 

 coracoid, one or two flat bones are always present in the scapular 

 region of the body : these, however, do not represent claviculse, 

 but may with certainty be determined as ossifications of the 

 sternum. The discovery, therefore, of what may be called a 

 supernumerary bone besides the sternal plates in two of the several 

 Diplodocus skeletons known to science proves to be of quite 

 exceptional interest. 



Hatcher, in his impoi'tant Monographs of the Dijylodocus 

 skeletons iSTos. 84 and 662 of the Carnegie Museum, desci-ibes 

 this element as follows : — ■" Throughout the greater portion of its 

 length it is circular in cross-section, it is bifid at one extremity 

 and slightly expanded at the other. It is strongly curved, 

 especially toward the bifid extremity. It is asymmetrical." In 

 a more complete specimen (No. 662) than the former (84) it is 

 '■'■ somewhat expanded and spatulate ; the flattened extremity 

 presents a slightly rugose surface, as though it had been imbedded 

 in cartilaginous or muscular tissue, and this together with the 

 bifid nature of the other extremity has suggested the possibility 

 that the bone might be an os penis." After the description of 

 this bone, however, its asymmetiy is I'egarded by this eminent 

 palaeontologist as a weighty argument against its being an os 

 penis, and therefore its identification with the clavicula is 

 advocated. 



* Coinmuuicated by Dr. A. Smith Woodward, F.R.S., F.Z.S. 

 Proc. Zool. Soc— 1905, Vol. II. No. XIX. 19 



