Radar, a Belgian draft horse and reigning Guinness World Record holder as the 'Tallest Living Horse,' at 19 hands 3.5 inches (6ft 6in), and Thumbelina, a miniature sorrel brown mare and the world's 'Smallest Living Horse,' 17.5 inches, are united for the first time for a photo shoot that will appear in the Guinness World Records 2008 edition, on sale August 7th.