title: The last diadectomorph sheds light on Late Palaeozoic tetrapod biogeography.
abstract: Diadectomorpha is a clade of Late Palaeozoic vertebrates widely recognized as the sister group of crown-group Amniota and the first tetrapod lineage to evolve high-fibre herbivory. Despite their evolutionary importance, diadectomorphs are restricted stratigraphically and geographically, with all records being from the Upper Carboniferous and Lower Permian of North America and Germany. We describe a new diadectomorph, Alveusdectes fenestralis, based on a partial skull from the Upper Permian of China. The new species exhibits the derived mechanism for herbivory and is recovered phylogenetically as a deeply nested diadectid. Approximately 16 Myr younger than any other diadectomorph, Alveusdectes is the product of at least a 46 Myr ghost lineage. How much of this time was probably spent in Russia and/or central Asia will remain unclear until a specimen is described that subdivides this cryptic history, but the lineage assuredly crossed this region before entering the relatively isolated continent of North China. The discovery of Alveusdectes raises important questions regarding diadectomorph extinction dynamics including what, if any, ecological factors limited the diversity of this group in eastern Pangea. It also suggests that increased sampling in Asia will likely significantly affect our views of clade and faunal insularity leading up to the Permo-Triassic extinction.
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, People's Republic of China liujun@ivpp.ac.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA.
authors.forename: G S
authors.initials: GS
authors.lastname: Bever
mesh_terms: D063147:Animal Distribution; D000818:Animals; D005075:Biological Evolution; D002681:China; D005580:Fossils / Q000033:anatomy & histology*; D060434:Herbivory; D010802:Phylogeny; D012886:Skull / Q000033:anatomy & histology; D014714:Vertebrates / Q000033:anatomy & histology* / Q000145:classification* / Q000502:physiology
keywords: China; Diadectomorpha; Pangea; Permian; biogeography