Fork and blade connecting rods

I thought that all V-x where x means 4,6,8,10,12, and 16 have one bank of cylinders offset from other bank because the connecting rods sit side-by-side but I found out from watching a video that there were some V-x where x means 8 and 12 have fork and blade connecting rods. The V-12 engines used in airplanes had overhead cams. The V-8 engines used in 1910s-1920s Cadillac and Lincoln had flatheads. How did the valve train work on those engines? I searched the Internet but I couldn't find anything.