6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 



species of this genus include falconeri (Lydekker, 1884), titan 

 (Wetmore, 1940), and pliocenicus (Zubareva, 1948). Of these only 

 falconeri is represented by a tibiotarsus that generally agrees with 

 Leptoptilos and is quite different from that of D. milleri. The 

 supratendinal bridge is shorter in the latter, and the distal opening 

 of the tendinal groove is oval rather than round. The posterior 

 portion of the condylar articulating surface is much broader in 

 Leptoptilos. The intercondylar groove is similar in shape in both 

 but broader in Leptoptilos. The external ligamental process is ridge- 

 like in Leptoptilos and longer, not short and papilla-like. The inner 

 lateral bulge is different in configuration in Leptoptilos. Finally, 

 the posterior tip of the inner condylar edge is pointed and sharply 

 angled in the fossil, while it is gently rounded in Leptoptilos. These 

 differences are considerable and indicate that that genus is not closely 

 related to Dissourodes. 



The fossil tibiotarsus is similar in size to that of Ephippiorhynchus 

 senegalensis, and its shaft is similar in shape. However, the latter 

 has a very narrow and deep condylar head very unlike that of 

 the fossil. Similarities between Ephippiorhynchus and Dissourodes 

 include : a narrow intercondylar groove ; an unnotched ridge between 

 the intercondylar tubercle and the external condyle ; an oval distal 

 opening of the tendinal groove ; and, a papilla-like external ligamental 

 process. However, the tibiotarsus of Ephippiorhynchus is distinctive 

 in several features, particularly in having a large process flaring 

 anteriorly and laterally from a position beside the proximal opening 

 of the tendinal groove. Dissourodes lacks such a process and has 

 a shorter external ligamental process and a more oval distal open- 

 ing of the tendinal groove. These and other minor configurational 

 differences preclude the fossil being included within Ephippiorhynchus. 



The modern Sphenorhynchus abdimii is much smaller than the 

 species represented by the fossil. There are a number of general 

 similarities between tibiotarsi of the two forms, including: the 

 similarly shaped distal opening of the tendinal groove, the agree- 

 ment between the two in length and shape of the papilla-like external 

 ligamental process, and the unnotched condition of the ridge between 

 the intercondylar tubercle and the external condyle. Although the 

 distal opening of the tendinal groove is oval in both Dissourodes and 

 Sphenorhynchus, that of the fossil does not angle laterally and 

 proximally as in Sphenorhynchus. The margin of the posterior 

 articulating surface is narrower in the fossil tibiotarsus. The posterior 

 intercondylar sulcus is deeper in the fossil and situated more toward 



