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JAMES H. GARDNER 

 SUMMARY OF GENERA AND SPECIES 



I 



The Puerco is a fauna wholly of Mesozoic origin, and mostly destined to 

 disappear; not a single representative or ancestor of any existing order of Ter- 

 tiary mammals is certainly known. Cope's opinion that many of these mammals 

 were ancestral to the modernized mammals lacks direct confirmation at present. 

 Other paleontologists, however, are inclined to connect certain of the creodont 

 families with the modem Carnivora. These and other ancestral connections 

 may be demonstrated in the future. 



Negatively, therefore, the Puerco is distinguished by the absence of primates, 

 rodents, true carnivores, specialized insectivores, artiodactyls, perissodactyls, 

 etc. This generalization has hardly less important bearings on paleogeography 

 than on paleozoology. 



PANTOLAMBDA ZONE (XORREJON FORMATION) 



Like the Puerco this is almost exclusively a Mesozoic fauna, destined 

 to become extinct during the Eocene. The known exceptions in 

 surviving types are the pro-Carnivora-Miacidae, which first appear 

 at this stage. Others will be discovered. 



Mammals of larger size, mostly evolved from the Puerco mammals. Last 

 survivors of the Multituberculata. Edentata-Taeniodonta of larger size. Of 

 archaic Ungulata, 2 orders and 3 families: (i) Condylarthra-Phenacodontidae, 

 (2) Amblypoda-Periptychidae, (3) Amblypoda-Pantolambdidae. Of the latter, 

 Pantolambda is supposed to be ancestral to the Coryphodontidae of the Wasatch. 

 Camivora-Creodonta, 4 families: (i) Mesonychidae, (4) pro-Camivora-Miacidae. 

 The primate-like Indrodon and aberrant Mixodectes are of unknown relationships; 

 they are possibly Insectivora. 



SUMMARY OF GENERA AND SPECIES 



