A new bystrowianid from the upper Permian of Germany: first record of a Permian chroniosuchian (Tetrapoda) outside Russia and China

ABSTRACT

An isolated dorsal osteoderm of a chroniosuchian from a late Permian fissure filling in the lower Zechstein (Z1) of central Germany represents the first Permian-age record of this enigmatic tetrapod clade outside Russia and China. Based on a number of features, the specimen is designated the holotype of a new taxon, Hassiacoscutum munki, and referred to the chroniosuchian clade Bystrowianidae. Phylogenetic analysis based on a recently published data set with addition of Hassiacoscutum and other recently described bystrowianids (Yumenerpeton, Jiyuanitectum, and Vyushkoviana) found good support for the clade Chroniosuchia and its subclades Chroniosuchidae and Bystrowianidae, but with little internal resolution for the latter. A second phylogenetic analysis of all known bystrowianid genera based solely on osteoderm characters yielded a well-supported and well-resolved clade Bystrowianidae with two subclades: (Yumenerpeton + (Synesuchus + Bystrowiella)) and (Jiyuanitectum + (Bystrowiana + (Hassiacoscutum + (Vyushkoviana + (Dromotectum + Axitectum))))). Hassiacoscutum provides a paleobiogeographic link to other middle and late Permian assemblages of Laurasian continental tetrapods. To date, chroniosuchians are known only from Laurasia, and their apparent absence in Gondwana hints at faunal provincialism across Pangaea.

ACKNOWLEDGMENTS

The National Geographic Society generously supported the excavations of the Korbach fissure. U. Markolf kindly granted permission to work in the quarry then owned by her family. The Hessisches Landesamt für Denkmalpflege and the Hessisches Ministerium für Wissenschaft und Kunst issued the requisite permits for excavation of the site. Work crews from the Waldeck-Frankenberg district authorities ably assisted in clearing and securing the site. For their capable and enthusiastic help in the field, we thank E. Frey, W. Munk, and R. Schuppiser (Staatliches Museum für Naturkunde Karlsruhe) and H. Kaufmann. Preparation of the material was enabled by the Museum für Naturkunde Berlin in cooperation of the city of Korbach, with the Wolfgang-Bonhage-Museum, the Geopark GrenzWelten, the Hessisches Landesamt für Denkmalpflege, the Hessisches Landesamt für Umwelt und Geologie, the Staatliches Museum für Naturkunde Karlsruhe, and the Senckenberg Gesellschaft für Naturforschung. V. Golubev (Borissiak Paleontological Institute of the Russian Academy of Sciences, Moscow) is thanked for access to the chroniosuchian material under his care. We thank M. Laurin and an anonymous reviewer for their thoughtful reviews.

ORCID

Hans-Dieter Sues http://orcid.org/0000-0002-9911-7254

Christian F. Kammerer http://orcid.org/0000-0002-0596-623X