Data of Paleozoic and some Early Triassic vascular land plant fossils from South China are synthetically analyzed,revealing evolutionary characteristics of Paleozoic vascular land plant diversity.Vascular land plant diversity keeps increasing in the Paleozoic as a whole.The Silurian witnessed the earliest evolution and initial diversification of land plants.From the Early Devonian to the Early Carboniferous(Mississippian),the great development,diversification,and differentiation really occurred in vascular land plants,with fluctuations of diversity,rapid replacement of the plant types,and an all-out takeover of terrestrial ecological niches.From the Early Permian,land plant diversity dramatically increased,and reached a climax in the Middle-Late Permian.Comparisons between late Paleozoic marine and terrestrial biodiversity reveal co-evolution of the late Paleozoic animals and plants as well as the individual evolutionary patterns of sea/land ecosystems.Vascular land plant diversity dramatically declined in the Frasnian as a result of the F/F event,and the end-Permian mass extinctions completely turned over the phytogroups.
Fossil insects from the Middle Jurassic of Daohugou, Inner Mongolia were investigated using Scanning Electron Microscope (SEM) for the first time, and portions and distribution of some elements in com-pression and pyrited fossils were also revealed by X-ray Energy Dispersive Spectroscopy (EDS) at-tached to SEM. Most of compression fossil insects from the Daohugou Biota are preserved in organic remains (diagenetic products of the original organic components). A small part of compression fossils retain a comparatively high Fe concentration which probably resulted from the absorption of Fe by biopolymers during the decaying period. Pyritized insect fossils suggest that the "fossil envelop" model found in the Early Cretaceous Jehol Biota probably also occurs in the Daohugou Biota. Different preservation modes show various mechanisms of fossilization, and also suggest that several different microenvironments are present in Daohugou palaeolakes.
Well-preserved and diversified spores,cryptospores,and acritarchs have been recorded from a relatively continuous sequence that encompasses the Silurian-Devonian boundary in Qujing, Yunnan,southwest China.Four spore assemblage zones from Late Silurian to Early Devonian in age are proposed based on the first appearance datum（FAD）of characteristic spore species.In ascending stratigraphic order,they are Ambitisporites dilutus-Apiculiretusispora synorea（DS;Late Ludfordian to Early Pridoli）,Synorisporites verrucatus-Apiculiretusispora plicata（VP;Pridoli）,Apiculiretusispora minuta-Leiotriletes ornatus（MO;Lochkovian）,and Verrucosisporites polygonalis-Dibolisporites wetteldorfensis（PW;Pragian）.The acritarch assemblage from the upper part of the Yulongsi Formation,the Xiaxishancun Formation,and the lower-middle parts of the Xitun Formation indicates an age of Late Silurian.Based on palynological evidence,the upper part of the Yulongsi Formation is considered Late Ludfordian to Early Pridoli in age;the Xiaxishancun Formation is believed to be Pridoli in age;the Xitun Formation is considered Late Pridoli to Early Lochkovian in age;the Guijiatun Formation is considered Lochkovian in age;and the Xujiachong Formation is Late Lochkovian to Pragian in age.The Silurian-Devonian boundary is recognized between the VP and the MO spore biozones,and occurs within the middle part of the Xitun Formation.
