Complex sentence: The 50-year period from 1890 to 1940, when the seven researchers above were working, was a period when the science of diplopodology flourished: rates of species descriptions during this period was on average the highest in history, sometimes exceeding 300 per year.
Split into simpler sentences: The 50-year period between 1890 and 1940, when the seven researchers above were working, was a period when the science of diplopodology flourished. Rates of species descriptions during this period was on average the highest in history, sometimes exceeding 300 per year.