A new morphometric approach was developed to study morphological variation within P1 elements commonly referred to as

No abstract

The upper Pennsylvanian Naqing and Narao carbonate successions were deposited in intra-platform slope-to-basinal settings across the Kasimovian-Gzhelian boundary in Guizhou, South China. Conodont faunas consist of a mixture of the endemic taxa of the Idiognathodus luodianensis group and cosmopolitan species of the I. simulator group. The I. luodianensis group includes the new species I. fengtingensis, I. luodianensis, I. naqingensis and I. naraoensis. On platform landmark analysis the species of the I. luodianensis group differ in morphological features from co-occurring species of the I. simulator group. Both groups display similar increasing asymmetry in P 1 element pairs across the Kasimovian-Gzhelian boundary, as recognized on the basis of the first occurrence of I. simulator. Many Kasimovian Idiognathodus species disappear and several Gzhelian species first appear with I. simulator, including two new species of Streptognathodus: S. nemyrovskae and S. zhihaoi. Just below the base of the Gzhelian, carbonate d 13 C falls from 4& to 2& in both sections. The combination of an abrupt faunal turnover immediately above the prominent negative d 13 C excursion might represent an oceanic event in South China, perhaps recognizable on a global scale. One of these two South China sections may be the best location to place the GSSP for the base of the Gzhelian Stage.

The global dispersal of forests and soils has been proposed as a cause for the Late Devonian mass extinctions of marine organisms, but detailed spatiotemporal records of forests and soils at that time remain lacking. We present data from microscopic and geochemical analyses of the Upper Devonian Chattanooga Shale (Famennian Stage). Plant residues (microfossils, vitrinite and inertinite) and biomarkers derived from terrestrial plants and wildfire occur throughout the stratigraphic section, suggesting widespread forest in the southern Appalachian Basin, a region with no macro plant fossil record during the Famennian. Inorganic geochemical results, as shown by increasing values of SiO 2 /Al 2 O 3 , Ti/Al, Zr/Al, and the Chemical Index of Alteration (CIA) upon time sequence, suggest enhanced continental weathering that may be attributed to the invasion of barren lands by rooted land plants. Our geochemical data collectively provide the oldest evidence of the influences of land plants from the southernmost Appalachian Basin. Our synthesis of vascular plant fossil record shows a more rapid process of afforestation and pedogenesis across south-central Euramerica during the Frasnian and Famennian than previously documented. Together, these results lead us to propose a new hypothesis that global floral dispersal had progressed southward along the Acadian landmass rapidly during the Late Devonian.