A new eryopid temnospondyl from the Carboniferous–Permian boundary of Germany

Abstract

A new eryopid temnospondyl, Stenokranio boldi n. gen. n. sp. is described based on well-preserved cranial and postcranial material from fluvio-lacustrine deposits of the Permo-Carboniferous (Gzhelian/Asselian) Remigiusberg Formation at the Remigiusberg quarry near Kusel, Saar–Nahe Basin, southwest Germany. The new taxon is characterized by three autapomorphies within the Eryopidae: (1) the relatively narrow posterior skull table, therefore nearly parallel lateral margins of the skull; (2) the short postparietals and tabulars; and (3) the wide ectopterygoid. Phylogenetic analysis reveals a monophyletic Eryopidae with the basal taxa Osteophorus, Glaukerpeton, and Onchiodon labyrinthicus forming a polytomy. Actinodon may be either a basal eryopid or a stereospondylomorph, and the genus Onchiodon is not monophyletic. Stenokranio n. gen. is found as a more derived eryopid forming the sister taxon to Eryops. Stenokranio n. gen. was among the largest predators of the Saar–Nahe Basin. Its semiaquatic lifestyle enabled Stenokranio n. gen. to browse riverbanks and lake shorelines for prey, but most likely it fed on aquatic vertebrates. Stenokranio n. gen. was part of a faunal assemblage of aquatic, semiaquatic, and fully terrestrial vertebrates, such as sarcopterygian and actinopterygian fishes, xenacanthid sharks, a dvinosaurian temnospondyl, different “lepospondyls”, diadectomorphs, and synapsids. This is in general accordance with the vertebrate community from the Permo-Carboniferous of North America and from the early Permian localities of Manebach (Thuringian Forest Basin) and Niederhäslich (Döhlen Basin). It is notable that the occurrence of Stenokranio n. gen. and other eryopids in these localities excluded the presence of other large temnospondyls such as Sclerocephalus. However, a previously described isolated eryopid mandible from the Remigiusberg locality differs from that of Stenokranio n. gen. in several characters, implying that probably two different eryopid taxa lived at the same locality. UUID: www.zoobank.org/88a52547-d6fc-40af-965c-a6786c252ed5