A REVISION OF THE COTYLOSAURIA 

 OF NORTH AMERICA. 



HISTORICAL REVIEW. 



The name Cotylosauria was first proposed by Cope in 1881 (21) in a description 

 of the skull of Empedias (Empedocles). He says: "The relations of the quadrate 

 and the zygomatic arches are as in the Theromorpha generally," and makes several 

 statements with regard to the palate and the brain case. The name was suggested 

 by the apparent double articulation of the skull with the vertebral column: "The 

 character of this articulation is so distinct from anything yet known among verte- 

 brated animals that I feel justified in proposing a new division for the Theromorpha 

 to include the Diadectidce, to be called the Cotylosauria." He evidently intended 

 this group to have rank as a suborder in the order Theromorpha. 



In June of the same year he published his "Second Contribution to the'History 

 of the Permian Formation of Texas" in the "Proceedings of the American Philosoph- 

 ical Society" (22); this also appeared separately as Paleontological Bulletin, No. 32. 

 In these papers the Cotylosauria is still reckoned as a suborder of the Theromorpha. 

 In a "Catalogue of the Vertebrata of the Permian Formation of the United 

 States," published in the "American Naturalist" for 1881 (23), the D/W^cr/^ is again 

 considered as a family of the suborder Pelycosauria, of the order Theromorpha and 

 the name Cotylosauria is dropped. 



In 1882 (25) Cope was still doubtful about the suborder Cotylosauria: 

 "I am still inclined to question whether the extraordinary characters of the 

 cranio-vertebral articulation I have described justify the separation of the Diadec- 

 tidce as a third suborder of the T heromorpha which I have called the Cotylosauria, or 

 whether they are due to the loss of a loosely articulated basioccipital bone." 



In no one of three papers published in 1885 (27, 28, 29) and indeed, not again 

 until 1889, does Cope make mention of the Cotylosauria in his classificatory lists. 



In 1888 Seeley (57) proposed as a classification of the primitive reptiles the 

 following: 



Subclass: Anomodontia. 

 Suborder: Pareiasauria. 

 Dicynodontta. 

 Gennetotheria. 

 Pelycosauria. 

 Thertodontta. 

 Cotylosauria. 

 Placodontia. 



In 1889 Seeley's full paper, of which the above is an extract, appeared in the 

 "Transactions of the Royal Philosophical Society" (58). He defines the suborder 

 Pareiasauria as having "Basioccipital articulation. No temporal vacuities. No 

 median bar to interclavicle." The suborder Cotylosauria he defined as having 

 "Exoccipital condyles. Molar teeth transversely developed." 



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