Complex sentence: This challenges the "Clovis First" model of Migration to the New World and it is possible that the first inhabitants of Valdivia and Chile travelled to America by watercraft and not across a land-bridge in the Bering Strait.
Split into simpler sentences: This challenges the "Clovis First" model of migration to the New World. Researchers speculate that the first inhabitants of Valdivia and Chile travelled to America by watercraft and not across a land-bridge in the Bering Strait.