A recently discovered tetrapod-bearing locality (OMNH V1005) in the Upper Pennsylvanian Ada Formation of Oklahoma has produced the remains of six taxa: the pelycosaurian-grade synapsid Ophiacodon cf. mirus, an indeterminate sphenacodontian pelycosaur, the temnospondyl Eryops? sp., the rare diadectid Diasparactus zenos, and two unidentified taxa known only from jaw fragments. The skeletal material comprises an allochthonous assemblage transported by low-velocity currents prior to burial. Except for four articulated Ophiacodon vertebral segments, all fossil material recovered in situ was disarticulated. The bones were not exposed to prolonged periods of weathering prior to burial. OMNH V1005 records the first occurrence of Eryops, Diasparactus, and Ophiacodon from the Pennsylvanian of Oklahoma. The presence of Diasparactus zenos indicates that this species was not endemic to New Mexico, as formerly believed. An associated dentary provides the first well-preserved cheek teeth of Diasparactus zenos. Compared to other North American diadectid genera, these teeth resemble more closely those of Diadectes than those of Desmatodon. The occurrence of Ophiacodon mirus, which was previously known from Lower Permian strata of New Mexico, extends both the stratigraphic and geographic range of this species. The Ada assemblage resembles those found in Permo-Carboniferous deltaic deposits in the southwestern United States.