Characteristics And Significance Of Fossil Plants Near The Top Of Wutong Formation In Chaohu

There are abundant late Paleozoic plant fossils in South China,many of which are considered to be the standard fossils of the Early Carboniferous in the world.However,the evolution of these plant fossils from the late Devonian to the Early Carboniferous remains to be further studied.In this paper,based on field survey of the near-top strata of the Devonian Wutong Formation at the Qilinshan section and Shizikou section in Chaohu City,Anhui Province,as well as the collection,description and research 9 genera(1suspected genus)and 24 species of fossil plants and 24 genera and 76 species of fossil spores in this paper.Near the top of Wutong Formation in Chaohu area of Anhui Province is Famennian,and the lower part of Jinling Formation is not divided into early Carboniferous.The characteristics of plant evolution are as follows: The intercostal ornamentation of leaf bases in Sublepidodendron mirabile from linear to water-striated;In addition to the basic characteristics such as spindle shape,narrow and long leaf bases shape and false wheel arrangement,the stem of Lepidodendropsis also has thin or thick horizontal lines;Expect the rhomboid or oblique square,the leaf base of Leptophloeum rhombicum may also be changed to round;The root marks of Stigmaria ficoides are not all arranged regularly and there are not smooth longitudinal diamond-shaped areas around the leaf base of the Bothrodendron(Cyclostigma).Moreover,the discovery of Archaeocalamites(species indeterminate)confirmed that the Archaeocalamites had appeared in the late Devonian in China.In the first period of the late Famennian,a small radiation was carried out in Lycopsida and Sphenopsida.From the late Devonian to the Early Carboniferous,the ratio of the length to width of the leaf base of Lycopodia changed from small to large,and the vascular bundle trace changed from unclear to clear.In the late Devonian,most of the leaves of Sphenophyllum were smaller,but larger leaves already existed at the same time.The Early Carboniferous plants are good inheritors of the late Devonian plants.The assemblage near the top of Wutong Formation in Chaohu,Anhui Province is Sublepidodendron-Sphenophyllum assemblage.