<i>Cyclotosaurus naraserluki, </i>sp. nov., a new Late Triassic cyclotosaurid (Amphibia, Temnospondyli) from the Fleming Fjord Formation of the Jameson Land Basin (East Greenland)

<i>Cyclotosaurus naraserluki</i>, sp. nov., is a new Late Triassic capitosaurid amphibian from lacustrine deposits in the Fleming Fjord Formation of the Jameson Land Basin in Greenland. It is based on a fairly complete and well-preserved skull associated with two vertebral intercentra. Previously reported as <i>Cyclotosaurus</i> cf. <i>posthumus</i>, <i>C. naraserluki</i> is unique among cyclotosaurs for having the postorbitals embaying the supratemporals posteromedially. The anterior palatal vacuity presents an autapomorphic complete subdivision by a wide medial premaxillary-vomerine bony connection. The parasphenoid projects between the pterygoids and the exoccipitals, preventing a suture between the two, a primitive condition shared with Rhinesuchidae, <i>Eryosuchus</i>, and <i>Kupferzellia</i>. Within <i>Cyclotosaurus</i>, the Greenlandic skull has a distinctive combination of circular choanae (shared with <i>C. ebrachensis</i>, <i>C. posthumus</i>, and <i>C. robustus</i>) and a convex posteromedial margin of the tabulars (also present in <i>C. ebrachensis</i> and <i>C. intermedius</i>). A phylogenetic analysis indicates that <i>C. naraserluki</i> is the sister taxon of the middle Norian <i>C. mordax</i> from southern Germany, with which it shares a pair of premaxillary foramina. <i>Cyclotosaurus</i> is one of the most successful and diverse genera of Late Triassic temnospondyls, with at least eight species reported from middle Carnian to late Norian. <i>Cyclotosaurus naraserluki</i> is the largest amphibian ever reported from Greenland and one of the Late Triassic vertebrates with the highest northern paleolatitude currently known. http://zoobank.org/urn:lsid:zoobank.org:pub:43AAA541-031C-4EE1-B819-4846EBBD1BBB SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Marzola, M., O. Mateus, N. H. Shubin, and L. B. Clemmensen. 2017. <i>Cyclotosaurus naraserluki</i>, sp. nov., a new Late Triassic cyclotosaurid (Amphibia, Temnospondyli) from the Fleming Fjord Formation of the Jameson Land Basin (East Greenland). Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1303501.