Review of recently collected material ofEohiodonfrom North America suggests that there are two valid species,E. rosei(Hussakof) andE. woodroffiWilson.Eohiodon falcatusGrande is identical toE. woodruffiin known skeletal features and nearly all meristic features and is treated as a junior synonym of the latter. The fossil genusEohiodonCavender differs fromHiodonLesueur, which is known from both fossil and extant species, in numerous meristic and osteological features. The caudal skeleton inEohiodonis nearly identical to that inHiodon.The traditionally accepted Notopteroidei, containing Lycopteridae, Hiodontidae, and Notopteridae, is a polypheletic group. The Asian fossil family Lycopteridae is not more closely related to Hiodontidae than it is to other taxa in the Osteoglossomorpha, but is sister to all other Osteoglossomorpha. The Hiodontiformes sensu stricto, including only the family Hiodontidae, is the sister-group of the Osteoglossiformes. This family is not more closely related to notopterids than to other taxa in Osteoglossiformes. The Notopteridae are most closely related to the Mormyroidea; together they and the fossil family Ostariostomidae constitute the sister-group of the Osteoglossoidei.Fossil records of Hiodontiformes sensu stricto and Notopteroidei indicate a widespread pre-Neogene biogeographic range of these freshwater teleosts, suggesting that extinction must have been involved in the Cenozoic evolution of these two osteoglossomorph sublineages.