part of lateral line development posterior lateral line system development posterior lateral line development PLL development biological_process GO:0048916 The process whose specific outcome is the progression of the posterior lateral line over time, from its formation to the mature structure. The posterior lateral line consists of small sensory patches (neuromasts) located superficially on the skin or just under the skin in fluid-filled canals on the body and trunk of all fishes and most amphibians. The posterior lateral line develops from cranial ectodermal placodes situated behind the ear.