Try to name reliable classic lines in the United States, and a couple immediately come to mind: Kentucky Derby winner Unbridled, who has founded a strong branch of the family tree for his grandsire, the prolific Mr. Prospector, and Belmont Stakes winner A.P. Indy, who represents Triple Crown winner Seattle Slew’s branch of the Bold Ruler line. Both are solidly represented in a Kentucky Derby field that is extremely hard to pick apart on pedigree.