Museums and Evolution

Evolution: Education and Outreach

, Volume 5, Issue 1, pp 29-37

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

Fossil Horses, Orthogenesis, and Communicating Evolution in Museums

  • Bruce J. MacFaddenAffiliated withFlorida Museum of Natural History, University of Florida Email author 
  • , Luz Helena OviedoAffiliated withFlorida Museum of Natural History, University of Florida
  • , Grace M. SeymourAffiliated withCornell University
  • , Shari EllisAffiliated withFlorida Museum of Natural History, University of Florida


The 55-million-year fossil record of horses (Family Equidae) has been frequently cited as a prime example of long-term macroevolution. In the second half of the nineteenth century, natural history museum exhibits characteristically depicted fossil horses to be a single, straight-line (orthogenetic) progression from ancestor to descendent. By the beginning of the twentieth century, however, paleontologists realized that, rather than representing orthogenesis, the evolutionary pattern of fossil horses was more correctly characterized by a complexly branching phylogenetic tree. We conducted a systematic survey of 20 fossil horse exhibits from natural history museums in the United States. Our resulting data indicate that more than half (55%) of natural history museums today still depict horse evolution as orthogenetic, despite the fact that paleontologists have known for a century that the actual evolutionary pattern of the Family Equidae is branching. Depicting outmoded evolutionary patterns and concepts via museum exhibits, such as fossils horses exemplifying orthogenesis, not only communicates outmoded knowledge but also likely contributes to general misconceptions about evolution for natural history museum visitors.


Exhibits Evolution Fossil Horses Museum Orthogenesis