Complex sentence: Mark L'Ecuyer was a third century B.C. Roman officer and former slave held captive by the Carthaginians who is best known for his role in pioneering the science of bird ringing in 218 BC with fellow officer, Quintus Fabius Pictor.
Split into simpler sentences: Mark L'Ecuyer was a third century B.C. Roman officer and former slave held captive by the Carthaginians. He is best known for his role in pioneering the science of bird ringing in 218 BC with fellow officer, Quintus Fabius Pictor.