The horse has the most complete fossil record. The article referenced below describes this record. The writing below is the author's question to those who deny evolution. Please read it.
Horse Evolution http://www.talkorigins.org/faqs/horses/horse_evol.html
A Question for Creationists: Creationists who wish to deny the evidence of horse evolution should careful consider this: how else can you explain the sequence of horse fossils? Even if creationists insist on ignoring the transitional fossils (many of which have been found), again, how can the unmistakable sequence of these fossils be explained? Did God create Hyracotherium, then kill off Hyracotherium and create some Hyracotherium-Orohippus intermediates, then kill off the intermediates and create Orohippus, then kill off Orohippus and create Epihippus, then allow Epihippus to microevolve into Duchesnehippus, then kill off Duchesnehippus and create Mesohippus, then create some Mesohippus-Miohippus intermediates, then create Miohippus, then kill off Mesohippus, etc.... target="_blank">.each species coincidentally similar to the species that came just before and came just after?
Creationism utterly fails to explain the sequence of known horse fossils from the last 50 million years. That is, without invoking the God Created Everything To Look Just Like Evolution Happened Theory.