Other paleontologists overlooked Marsh's brief mention of "Sphenacodon" for almost three decades. In the meantime, the sail-backed "Dimetrodon", named in 1878 by rival paleontologist Edward Drinker Cope, became a scientifically important genus, known from numerous fossils. Recognition of "Sphenacodon" as a low-spined carnivorous "pelycosaur" distinct from "Dimetrodon" came in the early 20th century with the discovery of more fossils in New Mexico. The proposed taxa "Elcabrosaurus baldwini" Case, 1907 and "Scoliomus" Williston and Case, 1913 now are considered junior synonyms of "Sphenacodon ferox".