Complex sentence: The Clovis culture, the earliest definitively dated prehistoric Paleo-Indian culture in the Americas, appears around 11,500 RCBP (radiocarbon years before present), equivalent to 13,500 to 13,000 calendar years ago.
Split into simpler sentences: The Clovis culture is the earliest definitively dated prehistoric Paleo-Indian culture in the Americas. It appears around 11,500 RCBP (radiocarbon years before present), equivalent to 13,500 to 13,000 calendar years ago.