Joseph Leidy
In 1856 Joseph Leidy had named fourteen teeth collected by Ferdinand Vandeveer Hayden in 1854 and 1855 from the Judith River Badlands of Montana as the species "Deinodon horridus". In 1866 Edward Drinker Cope chose three nonserrated teeth from the original syntype series of fourteen as the lectotypes of "Deinodon horridus".