mesolithic       
adjective  science specialized uk/ˌmes.əˈlɪθ.ɪk/ us/ˌmez.əˈlɪθ.ɪk/
 中石器时代的
relating to the middle part of the Stone Age (= the period when humans used tools and weapons made of stone)
  They believe that dogs were domesticated during the mesolithic age. 他们相信狗是在中石器时代被驯化的。 
 Compare: palaeolithicneolithic