Horse outward similarity is an unreliable measure of relatedness. Besides the horse, there are six other species of genus "Equus" in the Equidae family. These are the ass or donkey, "Equus asinus"; the mountain zebra, "Equus zebra"; plains zebra, "Equus quagga"; Grévy's zebra, "Equus grevyi"; the kiang, "Equus kiang"; and the onager, "Equus hemionus". Horses can crossbreed with other members of their genus. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, a hinny, is a cross between a stallion and a jenny (female donkey). Other hybrids include the zorse,
Peter the Great (horse) white star on his forehead and on the left hind leg a white sock. Peter the Great established the American Standardbred bloodline through the Hambletonian 10 offspring Happy Medium. During his life, Peter the Great covered thousands of mares. His tail-male pedigree was Pilot Medium/Happy Medium/Hambletonian. His tail-female pedigree was Santos by Grand Sentinel/Swallow by Joe Hooker/Dixie by Sam Johnson's horse/Dam by Cumberland. Peter the Great (horse) Peter The Great (1895–1923) was an American Standardbred horse. A descendant of Hambletonian 10, he is considered one of the most important sires in the development of the modern Standardbred breed. Peter the