Complex sentence: The centre of kingfisher diversity is the Australasian region, but the family is not thought to have originated there, instead they evolved in the Northern Hemisphere and invaded the Australasian region a number of times.
Split into simpler sentences: The centre of kingfisher diversity is the Australasian region, but the family is not thought to have originated there. Instead, they evolved in the Northern Hemisphere and invaded the Australasian region a number of times.