Late Triassic Conifers Reproductive Organs From Baojishan Basin,gansu Province,china And Their Paleoenvironmental Implications

Conifers plant are an important part of terrestrial plants.They have been in a dominant position from Late Paleozoic to Mesozoic.This dominant position continued until the end of Mesozoic Cretaceous,and then gradually replaced by gymnosperms.Therefore,whether it is discussing the Paleozoic and Mesozoic environmental and climate change,the extinction of terrestrial plants,or the transformation from the fern age to the gymnosperm age,conifers are the focus of debate;Conifers play an extremely important role in the geological history of plant evolution.Pines and cypresses mainly flourished in the Mesozoic,preserved many buried fossils and rich species;It contains not only a large number of branch fossils,but also reproductive organ fossils and various mineralized trees.It is an important coal making plant in the Mesozoic era.The Mesozoic strata of Baojishan Basin in Gansu Province are developed,in which abundant plant fossils are preserved in the Late Triassic nanyinger formation.In this paper,the reproductive organ fossils of pines and cypresses collected in this group were systematically studied.After carefully observing the macro structure and micro structure of Conifers plant reproductive organ fossils,and after careful comparison and discussion,the Conifers plant fossils studied in this study were classified and identified,and three new species of pine and cypress reproductive organs were identified: Pityostrobus baojishanensis Wang et Yan sp.nov.,Swedenborgia baojishanensis Wang et Yan sp.nov.,Scarburgia baojishanensis Wang et Yan sp.nov.3 genera and 4 species.We collect and analyze the fossil distribution of pine cone in the global paleogeography of Mesozoic and Cenozoic.According to the distribution characteristics of geological history,analyze its growth and living environment in the geological history period.It is found that the fossils of reproductive organs of Conifers plants are mainly distributed in the middle and high latitudes of the Mesozoic temperate zone,At the same time,it is found that pines represented by pine cone migrate from the eastern part of laurasia to the western part of laurasia.At the same time,the geographical distribution of pine cone and swedenberg in China is analyzed.It is found that they have certain North-South differences in geography.In each period,the distribution in the north is more than that in the south.It is speculated that the environment in the north is more suitable for the growth of Conifers plants than that in the south.Based on the plant fossil records of Baojishan Basin in the Late Triassic,it is inferred that the paleoclimate of Baojishan Basin in Gansu Province in the Late Triassic should be warm and humid,with sufficient rainfall,mostly flat terrain,local relatively convex mountains with high altitude or terrain,which is a complete forest ecosystem with abundant water and rich terrain;The forest ecological distribution is roughly as follows: tall trees such as pines and cypresses,ginkgo and other plants,shrubs and herbs such as cycads,true ferns and other plants are the main body.At the same time,it is associated with bryophytes and other plants.