Complex sentence: An early predecessor is Cox's timepiece, a clock developed in the 1760s by James Coxand and John Joseph Merlin, while the oldest predecessor still running today is the 1864 Beverly Clock.
Split into simpler sentences: An early predecessor is Cox's timepiece, a clock developed in the 1760s by James Cox and and John Joseph Merlin. The oldest predecessor still running today is the 1864 Beverly Clock.