Complex sentence: An polyploidy event 160 MYA is theorized to have created the ancestral line that led to all modern flowering plants; that event was theorized based on sequencing the genome of an ancient flowering plant, "Amborella trichopoda".
Split into simpler sentences: An polyploidy event 160 MYA is theorized to have created the ancestral line that led to all modern flowering plants. That paleopolyploidy event was studied by sequencing the genome of an ancient flowering plant, "Amborella trichopoda".