204 Mr Gadow, On the supposed relationship [Oct. 26, 



(2) Remarks on the supposed relationship of Birds and 

 Dinosaurs. By H. Gadow, M.A., Ph.D., F.R.S. 



It is least objectionable to divide the enormous order of 

 Dinosauri into the following four groups. 



I. Sauropoda. Premaxilla with teeth. Pubis single, with 

 symphysis. 



Fore- and hindlimbs pentadactyle and of the walking type, 

 plantigrade. 



Tarsalia free. 



Hereto belong : Atlantosaurus, Brontosaurus, Morosaurus, I)ip- 

 lodocus, mostly gigantic beasts from the Upper Jurassic of 

 Wyoming. Ornithopsis from the English Wealden. — These genera 

 of Sauropoda are not the ancestors of the other Dinosaurs. 



II. Theropoda. Carnivorous. Premaxilla with teeth. Pubis 

 simple, with symphysis. 



Forelimbs shorter than the hindlimbs ; digitigrade, with fre- 

 quently pronounced upright gait. The first and fifth metatarsals 

 and toes are often reduced. Proximal tarsalia with the tendency 

 to fuse with the tibia ; the astragalus sometimes with an ascending 

 process. Metatarsals elongated and sometimes fused with each 

 other. 



Hereto belong : Anchisaurus, from the Upper Triassic of 

 Connecticut ; in the same level of which are the Ornithichnites 

 (Brontozoum giganteum). Zanclodon from the Keuper of Wuert- 

 temberg. Megalosaurus from the Oolite of Europe and Colorado. 

 Allosaurus, Ceratosaurus, Goelurus, Hallopus from the Upper 

 Jurassic of North America. — Compsognathus from the Bavarian 

 Oolite : long neck, with slender ribs. Forelimbs much shortened, 

 but only three clawed fingers are known. The whole hindlimb is 

 almost typically avine ; the astragalus has an ascending process 

 and is fused with the tibia ; the distal tarsalia are fused with the 

 metatarsalia. The 2nd, 3rd and 4th metatarsalia are much 

 elongated and fused with each other, the 5th is very vestigial, and 

 the 1st is much reduced proximally and carries the hallux which 

 is placed backwards. The four toes have 2, 3; 4 and 4 (not 5) 

 phalanges. The fibula is slender. The femur mostly with an 

 inner (fourth) trochanter. 



III. Orthopoda. Herbivorous. Premaxilla without teeth. 

 With a premandibular edentulous piece, the so-called predentary 

 bone, which is probably a calcified horny pad. Each pubis consists 

 of an anterior and a posterior arm, the so-called prepubis (homolo- 

 gous with the " pubis " of most recent Reptiles and the pectineal 

 process of Birds) and the postpubis (homologous with the pro- 

 cessus lateralis pubis of Cheloniaus and Saurians, and with the 



