Complex sentence: He formerly co-anchored Prime News with Erica Hill until Hill was named the sole anchor; after Hill was reassigned to CNN in early 2008, Galanos returned to the program as her replacement.
Split into simpler sentences: He formerly co-anchored Prime News with Erica Hill until Hill was named the sole anchor. After Hill was reassigned to CNN in early 2008, Galanos returned to the program as her replacement.