festus -
Well, there is a sequence of well-preserved remains of extinct creatures each one closely resembling the earlier and latter finds - close enough to be considered the same species - that all together form a chain from a small fox-like creature to the modern horse.
There are in fact plenty of such sequences.
Obviously you know that archeologists never use superficial characteristics to identify species but very specific ones - a tooth is enough for them to tell the species independently from a shape of most any bone, specific muscle attachment, etc. When speculating about possible descendants/ancestors, they examine evolution of every such feature independently - evolution of a tooth, heel-bone, skull-feature, etc.
That does not of course absolutely prove that the species evolved rather than were Created as they are now.
One can still believe that modern life is a result of creation but must then admit that God went to a lot of trouble to arrange evidence suggesting of evolution - and evidence of existence of the Earth and the universe few billion years prior to the creation event. Could he have done that, was he able to? Why not. Why? Not a valid question for mortals.
miko