It's interesting you guys say that about his shoulder/sewing machine step. I thought, looks like an athletic son-of-a-gun, and if he weren't looking like he's gearing up to cowkick the guy behind him, and his head was down and his front legs were better positioned, he's pretty neat!
In the mid-19th century we didn't really have breeds in America yet. There were English Thoroughbreds imported from England and then many local types of horses. Registered breeds were a fad of the late 19th century (Saddlebreds 1891, Morgans 1894, Standardbreds 1879) and in those early days many horses could conceivably be registered in several studbooks (to be a Saddlebred a horse had to be able to perform a saddle gait, to be a Morgan have Justin Morgan in the pedigree, and to be a Standardbred had to trot or pace a mile under the standard time).