Article IV.— A COMPLETE SKELETON OF TELEO- 

 CERAS FOSSIGER. NOTES UPON THE GROWTH 

 AND SEXUAL CHARACTERS OF THIS SPECIES. 



By Henry Fairfield Osborn. 

 Plates IV and IVa. 



The remarkable series of Rhinoceros skulls in the Cope and 

 American Museum Collections from the Upper Miocene or Loup 

 Fork Beds of Kansas and Nebraska, has finally been prepared 

 for exhibition and research purposes. Associated with them, and 

 of very great value, is a complete skeleton representing an aged 

 female of very large size, mounted from materials belonging to 

 several individuals secured by our excavations in Phillips Co., 

 Kansas, under the direction of Dr. Wortman in the months of 

 September, October and November, 1894. 



By the comparison of the 16 skulls and 13 jaws, representing 

 both sexes and all stages of growth, we are enabled for tlie first 

 time to positively define the animal long known as Aphelops 

 fossiger, to distinguish it both from Rhinpceros and Acei atherium, 

 and point out its important sexual and individual variations. The 

 writer's attention was first drawn to the largely disregarded sexual 

 and age characters of fossil Ungulates in studying the group of 

 Titanotheres ;' the extinct Rhinoceroses conform to the laws 

 which were observed in that group, and which are familiar enough 

 among living types, namely : males, of larger size with more 

 robust and rugose skulls; horns, if present, more prominent; 

 canines largely developed ; incisors and anterior premolars dis- 

 appearing in adults. 



We owe to Hatcher^ the valuable demonstration that Aphelops 

 fossiger bore a terminal horn upon the nasals, although he as- 

 signed this character to a type which he supposed represented a 

 new species, namely, Teleoceras major. Hatcher's type of T. 



' 'The Cranial Evolution of Titanotherium,' Bull. Am. Mus. Nat. Hist., July i, 1896, 

 pp. I57-I97._ 



'■^ American Geologist, March, 1894, pp. 149-150. 



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