Complex sentence: Evidence suggests big-animal hunters crossed the Bering Strait from Eurasia into North America over a land and ice bridge (Beringia), that existed between 45,000--12,000 BCE (47,000--14,000 BP).
Split into simpler sentences: Evidence suggests big-animal hunters crossed the Bering Strait from Eurasia into North America over a land and ice bridge (Beringia). This bridge existed between 45,000--12,000 BCE (47,000--14,000 BP).