The Collaborative International Dictionary of English v.0.48:

Centuriator \Cen*tu"ri*a`tor\, Centurist \Cen"tu*rist\, n. [Cf.
   F. centuriateur.]
   An historian who distinguishes time by centuries, esp. one of
   those who wrote the "Magdeburg Centuries." See under
   Century. [R.]
   [1913 Webster]