112 A REVISION OF THE COTYLOSAURIA OF NORTH AMERICA 



Labidosaurus was a low, squat creature with relative large feet and a powerful 

 tail. It probably rested normally with the belly on the ground and only occasion- 

 ally assumed the more erect position shown in the accompanying reconstruction 

 (fig. 50) copied from Broili. Williston believes that the powerful hooked incisor 

 teeth may have been used to drag small invertebrates from crannies in the rock or 

 to detach closely clinging limpet-like forms. 



Family SEYMOURIDAE. 



Genus CONODECTES Cope. 



Conodectes favosus Cope. 



Characteristic specimen: The type. No. 4342 Am. Mus. Nat. Hist. Cope Coll. 



Conodectes was described by Cope with Otoccelus, and the two were placed in 

 the family Otoccelidce, but as Octocaelus is an amphibian the name of genus and 

 family are transferred to that class. Conodectes is represented by a single poorly 

 preserved skull, but as it is reptilian and resembles Seyniouria Broili very closely in 

 some respects it is united with that genus in the family Seymourida. 



The skull is in such wretched condition that the sutures can not be made and it 

 has been largely restored in plaster by Cope. 



The otic region is peculiar in the elongation of the epiotic notch at the anterior 

 end. This is continued inward and downward until it terminates in a deep pit. 

 On the lower surface the broad plates of the prevomers, palatines, and pterygoids 

 can be made out. The latter approach each other in the median line, and this is the 

 chief reason why the animal is regarded as a reptile. There is no trace of teeth on 

 these bones, but there may have been such in life. The maxillary teeth were uniform 

 in size, but are too poorly preserved to show more than their form. Broken teeth 

 do not show any radiation of the dentine from a pulp cavity. The parasphenoid 

 was apparently of small size. 



Genus SEYMOURIA Broili. 

 Seymouria baylorensis Broili. (Plate 13.) 



Characteristic specimen : The type in the Museum of the Alte Akademie, 

 Munich. 



The Cotylosauria can no longer be regarded as the primitive type of the reptile, 

 as the bones of the temporal region are widely different from those of the Stegocepha- 

 lia. Broili (5, 6) has amply demonstrated the strikingly amphibian resemblances of 

 Seymouria, but his original belief that there were three bones in the temporal region 

 is unfounded, and Seymouria takes its place close to Captorhtnus and Labidosaurus. 

 The presence of an intertemporal bone places it in a distinct family. The sugges- 

 tions, founded on Broili's belief in the presence of three bones in the temporal 

 region, that Seymouria would perhaps turn out to be the connecting form between 

 amphibians and reptiles, must be abandoned. Such a form when found will prob- 

 ably be among the numerous small forms which were so abundant at the close of the 

 Carboniferous. 



The holospondylus vertebrae and the small parasphenoid are the characters 

 which proclaim its reptilian nature. 



The structure of the palate, shoulder-girdle, and ribs in Seymouria is similar to 

 that of the Labidosaurus; the skull is wonderfully Stegocephalian, but the structure 

 of the shoulder-girdle in Labidosaurus is so much like that of such Stegocephalians 

 as Trimerorhachis that Seymouria approaches very closely to both classes. 



