only the balistids and the derivative monacanthids are 

 not found in the Eocene. The balistids, of triacanthid 

 derivation, are first known from the Oligocene, with 

 genera rather similar to those alive today, while the 

 monacanthids as yet have no known fossil record. The 

 fossil record of the gymnodonts is not as impressive for 

 overall antiquity, quantity, or quality as that of the 

 scleroderms, with only the diodontids and, probably, the 

 tetraodontids known from the Eocene, again from Monte 



ll;-s-s 



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Bolca. Triodontids have been described from the Eocene 

 of Africa and Europe (not including Monte Bolca), but 

 only on the basis of jaws alone, with the dentaries fused 

 into a single piece and the premaxillaries separate. The 

 teeth in these jaws are small rounded units such as are 

 found in Triodon and diodontids, but this is scarcely suf- 

 ficient evidence of a fish of truly 7>iodon-like general 

 configuration in the Eocene. Molids are first known from 

 the Miocene. 



