ABSTRACT

The dissorophid genus Conjunctio (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 Conjunctio cf. C. multidens 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 Conjunctio, 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 Conjunctio at the specimen-level, and found a monophyletic Conjunctio at the base of Eucacopinae. The clade also included the earliest Permian Reiszerpeton and Scapanops in relatively basal positions, and an unresolved polytomy among the later Permian Cacops, Kamacops, Zygosaurus, and Anakamacops. Geographically, the discovery of Conjunctio 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.

摘要

所述dissorophid属的契合（离片锥目）的特征在于差，只从上埃尔铜业谷组两个不完整的标本已知的（降低二叠），卡特勒集团，美国新墨西哥州尽管如此，分类单元的保守形态和地层发生靠近石炭-二叠界线（大约2.99亿年前）使其成为解决歧管虫早期多样化的重要数据。我们报告了Conjunctio cf的首次出现。科罗拉多州圣米格尔县毗邻的未割裂的卡特勒岩层中的C. multidens，也仅代表了科罗拉多州西南部历史悠久的普莱瑟维尔组合中的第二个梭虫。新标本突出了结膜的多形性解剖，具有新近描述的下颌和颅后数据，并为与桉木科的关系提供了进一步的证据。我们通过修改先前发布的102个颅齿和颅后特征矩阵，在标本水平上对结膜进行评分，对34个替诺pondyl分类群进行了系统发育分析，并在桉树基部发现了单系结膜。进化枝还包括相对基础位置的最早的二叠纪Reiszerpeton和Scapanops，以及后来的二叠纪Cacops，Kamacops，Zygosaurus和Anakamacops尚未解决的多角体病。在地理上，发现契合。在普莱瑟维尔组合中是一个更广泛的美国西南部Wolfcampian动物，相关于在新墨西哥州北部的El上铜业谷组的一致，并可能强调二叠纪早期四足动物之间的组合之前提出的区域乡土。