INTRODUCTION. 9 



The remains of the Dinocerata are imbedded usually in indurated 

 clays, gray or green in color, but sometimes they are found in hard 

 sandstone. The series of strata enclosing them are at least five hundred 

 feet in thickness in the same region, and all taken together are probably 

 one thousand feet. 



Among the fossils found associated with the Dinocerata are LimnoJiyus 

 and Palmosiiops, two genera of perissodactyl ungulates. They were 

 somewhat larger than a Tapir, and in these strata are next in size to the 

 Dinocerata. One or the other of these genera occurs wherever the 

 Dinocerata have yet been fomid, but the remains extend through a greater 

 thickness of strata tlian those of the former group. Another genus of 

 ungulates in tliis horizon is OrohippHS^ a four-toed ancestor of the horse. 

 Other prominent genera ai-e CoJonoceras, Helaletes, and Hyracltyus, related 

 distantly to the Tapir and Rliinoceros. 



"Ywo genera, TiUotherium and Stiflinodon, also found here, represent a 

 remarkable order, named by the author, Tillodontia. Tliey were nearly 

 as large as a Tapir, and possessed characters resembling the Ungulates, 

 the Garni vors, and the Rodents. 



Among the Carnivors, the most 'formidable was Linmofelis, nearly as 

 large as a lion, Oreoci/on, of almost equal size, Dromocyon, somewhat 

 smaller, and Liwnocyon, about as large as a fox. Among the Lemuroid 

 forms were Hyopsodtis and Lemuravus, fonning the family Leinnravidee, 

 and having some affinities with the South American Marmosets. 



In addition to these, there were Marsupials, Insectivors, Chiroptera, 

 and many Rodents, but apparently no true Quadrumana, or Edentates. 



Besides these Mammals, there were numerous Reptiles, especially 

 crocodiles, turtles, lizards, and serpents, in great numbers. Fishes were 

 also abundant, especially the genera Amia and Lepidosteus. 



The Dinocerata form a well marked order in the great group of 

 Unf/iduta. In ^some of their characters, they resemble the Artiodactvls 

 ( Faraxonia); in others, ^%y are like the Perissodactyls (Mesaxonia); and 



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