The Collaborative International Dictionary of English v.0.48:

chinchillon \chinchillon\ n.
   a gregarious burrowing rodent (Lagostomus maximus) larger
   than the chinchillas.

   Syn: viscacha, Lagostomus maximus.
        [WordNet 1.5] Chinchona

WordNet (r) 3.0 (2006):

chinchillon
    n 1: gregarious burrowing rodent larger than the chinchillas
         [syn: viscacha, chinchillon, Lagostomus maximus]