 In the decades following Romer and Price 's monograph , many Dimetrodon specimens were described from localities outside Texas and Oklahoma . The first was described from the Four Corners region of Utah in 1966 and another was described from Arizona in 1969 . In 1975 , Olson reported Dimetrodon material from Ohio . A new species of Dimetrodon called D. occidentalis ( meaning " western Dimetrodon " ) was named in 1977 from New Mexico . The specimens found in Utah and Arizona probably also belong to D. occidentalis . 
