Complex sentence: The earliest known reverse contrast types date to about 1821, and were developed by the H.W. Caslon company in London, presumably as a parody of Didone types of the period, although they may have appeared in France slightly earlier.
Split into simpler sentences: The earliest known reverse contrast types date to about 1821. They were apparently developed by the H.W. Caslon company in London, presumably as a parody of Didone types of the period, although they may have appeared in France slightly earlier.