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

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. [ABSTRACT FROM AUTHOR]