The process whose specific outcome is the progression of the mechanosensory lateral line system over time, from its formation to the mature structure. The mechanosensory lateral line system consists of small sensory patches (neuromasts) located superficially on the skin or just under the skin in fluid-filled canals on the head and body of all fishes and most amphibians. The neuromasts are innervated by several lateral line nerves, which project primarily to the hindbrain. The mechanosensory lateral line system is stimulated by local water displacements and vibrations, and detects propulsion of the fish through the water, as well as facilitating shoaling, prey capture, and predator and obstacle avoidance.