Additional field and laboratory investigation of the Midco Member of the middle Wellington Formation, Lower Permian in Noble County, Northern Oklahoma has produced an abundance of vertebrate fossils from a 5 cm thick black silty clay. To date the most notable discovery is bones of the long-horned diplocaulid Diploceraspis which were previously only known from the upper Pennsylvanian and lower Permian of southwest Pennsylvania, southeast Ohio, and northwest West Virginia and the upper Pennsylvanian of southeastern Nebraska. This represents the first reported Permian occurrence of the amphibian Diploceraspis west of the of the Ohio River drainage area of Pennsylvania, Ohio, and West Virginia and therefore greatly increases the geographical range of the genus. Prior to this discovery, Diplocaulus magnicornis was the only long-horned diplocaulid known from the lower Permian of Oklahoma. The identifiable Diploceraspis material recovered consist of 5 partial tabular bones and one dorsal vertebra.