ABSTRACT

Recently collected temnospondyl fossils from the Cisuralian Pedra de Fogo Formation (north-eastern Brazil) indicate a diverse assemblage of aquatic tetrapods, including the dvinosaurs Timonya anneae and Procuhy nazariensis. Here we present revised diagnoses for these species and detailed descriptions of their holotypes. Timonya anneae is distinguished from all other dvinosaurs by several cranial characters including: combined width of both parietals less than interorbital width; presence of a groove-like internal carotid artery foramen; and presence of an ossified opisthotic. In the mandible, T. anneae presents two parasymphyseal fossae on each side of the mandibular symphysis to accommodate palatal fangs and a well-developed postglenoid area. Procuhy nazariensis, mostly preserved as a mold of the skull table and mandible, is diagnosed by the presence of the anteriormost extension of the squamosal posterior to parietal midlength; pineal foramen posterior to the midlength of the parietal; supratemporal exposed on the posterior border of the skull table; and presence of postglenoid process of the surangular separated from the retroarticular process of the articular by the mandibular sulcus. A new inclusive phylogeny of Temnospondyli indicates that Dvinosauria consists of the Trimerorhachidae (including Procuhy as the sister-taxon of Trimerorhachis) and the ‘short-snouted’ dvinosaurs, with Timonya as an early-diverging representative of the latter clade. The Pedra de Fogo dvinosaurs show close relationships with Cisuralian taxa from the North American southwest, reinforcing close paleogeographic connections between these regions in the late Paleozoic, but represent endemic taxa, corroborating the pattern suggested by the plant fossil record.

摘要

最近从 Cisuralian Pedra de Fogo 组（巴西东北部）收集到的 temnospondyl 化石表明水生四足动物的多样化组合，包括 dvinosaurs Timonya anneae和Procuhy nazariensis。在这里，我们提出了这些物种的修订诊断及其正模的详细描述。Timonya anneae与所有其他双龙的区别在于几个颅骨特征，包括： 两个顶骨的总宽度小于眶间宽度；存在凹槽状颈内动脉孔；和骨化的矫正器的存在。在下颌骨中，T. anneae在下颌联合的每一侧呈现两个副交界窝，以容纳腭尖和发达的关节盂后区域。Procuhy nazariensis，主要保存为颅骨表和下颌骨的模具，通过在顶骨中长后的鳞状骨的最前部延伸的存在来诊断; 顶叶中长后方的松果体孔；颞上暴露于颅骨表后缘；并且存在下颌骨沟与关节后关节突分开的关节盂后突。离片锥目的一种新的包容性发展史表明，Dvinosauria由Trimerorhachidae（包括Procuhy为一体的姐妹类群Trimerorhachis) 和“短鼻”dvinosaurs，其中Timonya作为后一个进化枝的早期分化代表。Pedra de Fogo dvinosaurs 与来自北美西南部的 Cisuralian 类群有着密切的关系，在晚古生代加强了这些地区之间密切的古地理联系，但代表了地方性类群，证实了植物化石记录所暗示的模式。