New Information on the Dissorophid <i>Conjunctio</i> (Temnospondyli) Based on a Specimen from the Cutler Formation of Colorado, U.S.A.

The dissorophid genus <i>Conjunctio</i> (Temnospondyli) is poorly characterized, known only from two incomplete specimens from the upper El Cobre Canyon Formation (lower Permian), Cutler Group, New Mexico, U.S.A. Nonetheless, the taxon’s conserved morphology and stratigraphic occurrence near the Carboniferous–Permian boundary (ca. 299 million years ago) make it an important datum to resolve the early diversification of dissorophids. We report the first occurrence of <i>Conjunctio</i> cf. <i>C. multidens</i> in the adjacent undivided Cutler Formation of San Miguel County, Colorado, which also represents only the second dissorophid from southwestern Colorado’s historic Placerville assemblage. The new specimen highlights the plesiomorphic anatomy of <i>Conjunctio</i>, with newly described mandibular and postcranial data, and provides further evidence for a relationship to the Eucacopinae. We performed a phylogenetic analysis of 34 temnospondyl taxa by modifying a previously published matrix of 102 craniodental and postcranial characters, scoring <i>Conjunctio</i> at the specimen-level, and found a monophyletic <i>Conjunctio</i> at the base of Eucacopinae. The clade also included the earliest Permian <i>Reiszerpeton</i> and <i>Scapanops</i> in relatively basal positions, and an unresolved polytomy among the later Permian <i>Cacops</i>, <i>Kamacops</i>, <i>Zygosaurus</i>, and <i>Anakamacops</i>. Geographically, the discovery of <i>Conjunctio</i> among the Placerville assemblage is consistent with a broader southwestern U.S. Wolfcampian fauna, correlative to that of the upper El Cobre Canyon Formation in northern New Mexico, and may underscore previously proposed regional provincialism among early Permian tetrapod assemblages.