The American Museum of Natural History owns the largest collection of fossil-horse skeletons in the world; since the early years of this century, their exhibition has represented a classic demonstration of evolution. Indeed, by looking carefully at this complex and multifaceted display, we learn not only about the evolution of the horse, but also about the development of scientific views of evolution in general.
The fossil horses aligned from right to left in the front of the display represent the evolution of horses as a steady progression along a single pathway -- until recently a widely held view of evolution. Here the horse is seen to evolve in a neat, predictable line, gradually getting larger, with fewer toes and longer teeth. Those arranged (also from right to left) in the back present a more current scientific view of evolution, determined through a method of analysis called cladistics, which has shown evolution to be a more complex, branching history, much like the genealogical history of your own family.
Cladistics, which the Museum has played an important role in developing, is the grouping of organisms by shared, specialized characteristics; each time a new evolutionary feature appears, a new branch grows on the evolutionary tree, comprising organisms that have both the old traits and the new one. Thus the display in the back shows that some later horses, such as Calippus, are actually smaller than earlier ones, and that other later horses, such as Neohipparion, still had three toes. This display is therefore both a classic demonstration of evolution and a paradigm of scientific method at the Museum.
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