Fig. 2
From: Fossil Horses, Orthogenesis, and Communicating Evolution in Museums
Classic straight-line (orthogenetic) depiction of fossil horse evolution in a natural history museum exhibit in the early twentieth century (Matthew 1926). In this depiction, fossil specimens are arranged in a temporal sequence starting with the older fossil species of “eohippus” (Hyracotherium) at the bottom and ending with the genus of modern horse Equus at the top. In addition to depicting orthogenesis, this graphic display implicitly communicates nineteenth-century notions of evolution representing progress or improvement