The Global Stratotype Section and Point （GSSP） for the boundary between the Capitanian and Wuchiapingian stages, also the boundary between the Guadalupian and Lopingian Series is defined at the First Appearance Datum （FAD） of the conodont Clarkina postbitteri postbitteri at the base of Bed 6k in the Penglaitan Section along the Hongshui River in Guangxi Province, South China. This point is within a chronomorphocline from Clarkina postbitteri hongshuiensis to C. dukouensis and nearly coincides with the Middle-Upper Absaroka Megasequence boundary and as such is documented within a continuously deposited carbonate lowstand succession with deep-water facies of the Maokou Formation below and deep-water facies of the Heshan Formation above. Furthermore, this point also coincides with a major extinction of various Permian fossils including corals, fusulinaceans, ammonoids and brachiopods. The proximity to an apparently global major sequence boundary and extinction event will serve as a means of correlation of this GSSP into other regions in which the defining taxon is not present because of profound provincialism during the Middle and Upper Permian. Carbon isotopic trends and magnetostratigraphic signatures are also provided to help correlate this GSSP into other regions, including those with continental facies successions. The Tieqiao Section near the county town of Laibin is also described as a supplementary reference section.
Yugan JinShuzhong ShenCharles M. HendersonXiangdong WangWei WangYue WangChangqun CaoQinghua Shang
The last two decades have witnessed great advances in reconstructing the transition from non-avian theropods to avians,but views in opposition to the theropod hypothesis still exist.Here we highlight one issue that is often considered to raise problems for the theropod hypothesis of avian origins,i.e.the "temporal paradox" in the stratigraphic distribution of theropod fossils - the idea that the earliest known avian is from the Late Jurassic but most other coelurosaurian groups are poorly known in the Jurassic,implying that avians arose before their supposed ancestors.However,a number of Jurassic nonavian coelurosaurian theropods have recently been discovered,thus documenting the presence of most of the major coelurosaurian groups in the Jurassic alongside,or prior to,avians.These discoveries have greatly improved the congruence between stratigraphy and phylogeny for derived theropods and,effectively,they reject the "temporal paradox" concept.Most importantly,these discoveries provide significant new information that supports the relatively basal positions of the Tyrannosauroidea and Alvarezsauroidea among the Coeluro-sauria.Indeed,they imply a new phylogenetic hypothesis for the interrelationships of Paraves,in which Archaeopteryx,the Dromaeosauridae,and the Troodontidae form a monophyletic group while the Scansoriopterygidae,other basal birds,and probably also the Oviraptorosauria,form another clade.Mapping some of the salient features onto a temporally-calibrated theropod phy-logeny indicates that characteristics related to flight and arboreality evolved at the base of the Paraves,earlier than the Late Jurassic.
