Middle Miocene
The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages . 
<triplet> Miocene <subj> Epoch <obj> instance of <subj> Langhian <obj> has part <subj> Serravallian <obj> has part <triplet> Langhian <subj> Miocene <obj> part of <subj> stages <obj> instance of <triplet> Serravallian <subj> Miocene <obj> part of <subj> stages <obj> instance of