HISTORY OF THE EDENTATA 625 



modification in these extraordinary animals, because of their 

 fragmentary condition. The oldest stage in which representa- 

 tives of the suborder have been detected is the Astrapo- 

 notus beds, which may be Oligocene or upper Eocene. On 

 the face of the records, therefore, the fgiyptodonts had no 

 such antiquity as the armadillos. 



It has long been recognized that the Edentata occupy a very 

 isolated position among the placental mammals ; their relation- 

 ships to other orders and their point of departure from the 

 main stem are unsolved problems. The South American 

 fossils have so far thrown little light into these dark places, 

 but they bear very cogent witness to the unity of origin of the 

 five suborders, which were most probably all derived from a 

 single early Eocene or Paleocene group. 



In the Paleocene and through most of the Eocene of North 

 America there lived an order of mammals called the fTaenio- 

 dontia (or fGanodonta) which many of the foremost palaeon- 

 tologists regard as an ancestral type of the Edentata, and Dr. 

 Schlosser actually includes them in that order. That the 

 ftseniodonts had certain striking resemblances to the edentates, 

 especially to the fground-sloths, is not to be denied, but the 

 interpretation of these resemblances is a verj^ complex and 

 difficult question. Unfortunately, no member of the order 

 is known from an even approximately complete skeleton, and 

 therefore a discussion of the matter here would be unprofitable. 

 My own conclusion, however, may be stated, to the efTect that 

 the supposed relationship of the ftseniodonts to the edentates 

 is illusory and not real. Definite decision must await the find- 

 ing of more complete material both of the ftseniodonts and the 

 most ancient South American edentates. 



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