From Wiktionary, the free dictionary
From mid- + posterior.
midposterior (not comparable)
- In the middle of the posterior part
2015 December 17, “A New Sail-Backed Styracosternan (Dinosauria: Ornithopoda) from the Early Cretaceous of Morella, Spain”, in PLOS ONE[1], →DOI:The fibular condyle projects laterally and possesses a shallow notch in the midposterior part.