Ectosteorhachis

Ectosteorhachis is an extinct genus of freshwater megalichthyid tetrapodomorphs that inhabited what is now North America during the Permian period. It is the only known member of the subfamily Ectosteorhachinae. Fossil remains are known from the United States.
It contains a single species, E. nitidus from the Asselian/Sakmarian to Kungurian of Oklahoma and Utah. A second species, E. ciceronius Edward [Drinker Cope|Cope], 1883 from the Garber Formation of Oklahoma has no type specimen and is thus invalid. Remains tentatively assigned to Ectosteorhachis are known from the Washington Formation of Ohio.