A redescription of Kunpania scopulusa, a bidentalian dicynodont (Therapsida, Anomodontia) from the ?Guadalupian of northwestern China

Abstract

Permian dicynodonts were discovered in strata exposed on the flanks of the Bogda Mountains (Xinjiang, China) in 1928. Nearly all known specimens were collected in the Guodikeng Formation (= upper Wutonggou low-order cycle); the single exception is the holotype of Kunpania scopulusa, which originated in the underlying Quanzijie Formation. The Quanzijie Formation is generally considered Capitanian in age, which would make Kunpania one of the oldest known bidentalian dicynodonts, but the type of K. scopulusa has received little attention. Here we redescribe K. scopulusa and investigate its phylogenetic relationships. Kunpania scopulusa is a valid species diagnosed by the absence of anterior palatal ridges; a robust crista oesophagea; a prominent lateral dentary shelf; a posteriorly curving projection on the angular; and a large, triangular attachment area for M. latissimus dorsi on the humerus. Our phylogenetic analysis recovered K. scopulusa as a stemward member of Dicynodontoidea and the sister taxon of the South African species Sintocephalus alticeps. Depending on the precise age of the uppermost Quanzijie Formation, three scenarios describe the potential phylogenetic implications of K. scopulusa: (1) bidentalian dicynodonts diversified before the end-Guadalupian extinction, with little of their early history preserved; (2) the main diversifications of cryptodont and dicynodontoid bidentalians occurred in the aftermath of the end-Guadalupian extinction, with K. scopulusa representing the latter; (3) K. scopulusa is a contemporary of other mid-late Wuchiapingian dicynodontoids and the initial radiation of Dicynodontoidea is not preserved in the known fossil record.

The evolution of the synapsid tusk: insights from dicynodont therapsid tusk histology

“…We further consider these developmental pathways in a phylogenetic context with the sample of dicynodonts studied here. There are multiple hypothesized phylogenetic arrangements for the taxa included in this study (see electronic supplementary material, figure S2), although most recent phylogenies [67][68][69][70] support a topology similar to that proposed by Angielczyk & Kammerer [47] (figure 3). In all phylogenetic arrangements, the caniniform position in royalsocietypublishing.org/journal/rspb Proc.…”

Histology and μCT reveal the unique evolution and development of multiple tooth rows in the synapsid Endothiodon

“…, Kammerer and Ordoñez 106 , and Angielczyk et al 107 , but note that other topologies for Pristerodon, Brachyprosopus, the endothiodonts, and the emydopoids have appeared in recent phylogenetic analyses 42,108,109 . Branch lengths are arbitrary.…”

“…'Postcanines' are typically located in the maxilla, although the anteriormost two teeth of Abajudon and Endothiodon are located in the premaxilla. Phylogeny based on Olroyd et al47 , Kammerer and Ordoñez 106 , and Angielczyk et al107 , but note that other topologies for Pristerodon, Brachyprosopus, the endothiodonts, and the emydopoids have appeared in recent phylogenetic analyses42,108,109 . Branch lengths are arbitrary.…”

“…Cladogram illustrating changes in tooth replacement across stemward dicynodonts. Phylogeny based on Olroyd et al47 , Kammerer and Ordoñez106 , and Angielczyk et al107 , but note that other topologies for Pristerodon, Brachyprosopus, the endothiodonts, and the emydopoids have appeared in recent phylogenetic analyses42,108,109 . …”

The emblematic South African therocephalian Euchambersia in China: a new link in the dispersal of late Permian vertebrates across Pangea

“…[25]), it is becoming increasingly clear that tetrapod late Permian distribution of genera from the northern and southern continents is rare, and reflected thus far in therapsids: dicynodonts Diictodon, Lystrosaurus, Geikia and the cynodont Procynosuchus (table 1). Four other cases of therapsid genera (three dicynodonts and one biarmosuchid) from southern Pangea were recovered in recent phylogenies as closely related to northern Pangea representatives [28][29][30][31][32]. Recently discovered new therocephalian genera in Zambia were also found to be closely related to Russian taxa, increasing the evidence of a close link between northern and southern faunas [15,16].…”