Numerical Classification Of Trapa Fruits And High Resolution Reconstruction Of Paleoclimate In Late Miocene Zhejiang Province

As one of the main types of life,plants play the role of producers in the biological of Kingdom.They are highly sensitive and dependent on the environment,so certain climates and environments support only certain plants.Therefore,flora can reflect the climate and environment of the growing area,and it is an important indicator to determine the climate and environment.The Shengxian Formation in the Miocene of Zhejiang Province contains a large number of plant fossils and abundant species,which is a natural Lagerstatten of plant fossils.The preservation of fossils is mainly leaf fossils,of which dicotyledons account for a large proportion.In addition,there are many fruit fossils of Trapa in this stratum,which occupies an absolute dominant position in quantity.In this paper,the Trapa fruit found in the Shengxian Formation is taken as the main research object,and the numerical classification method is used to classify plants of Trapa to identify them accurately.In order to know the evolution trend of late Miocene Trapa plants and paleoclimate,the Shengxian formation in Tiantai-Ninghai area of Zhejiang Province is divided into five layers,JHU0,DLX,JHU1,JHUW,JHU3 from old to new.Using the method of Leaf Margin Analysis and Climate-Leaf Analysis Multivariate Program,the high resolution paleoclimate restoration can be achieved according to the dicotyledonous leaves of each layer.During the burial process,the starch of the Trapa fruit was dissolved and lost,resulting in flattened fossils.Based on the cluster analysis of laterally and vertically compressed fruit fossils of Trapa,a certain morphological species was obtained,and then the three-dimensional appearance of Trapa fruit growth period was restored.This species is stereoscopic and plump,its core fruit body is spindle shaped,with 4 narrow triangle large-angles,clear head,prominent neck and covered with hairs on the top,the upper horns grows upward and has spines,the lower horns grows upward or straightly and the growth position is slightly lower than the upper horns,4 conical tubercles grow between the upper horns and the lower horns,the lower fruit body is triangular,and the base of the fruit body has residual stalk.The author tried to use numerical analysis methods to identify and classify the species.The results of Q-type Cluster Analysis of the morphological species and the present species show that the relationship between the species and the extant speciesspecies is far away,only slightly close to the relationship between the species and T.mammillifera.After that,the morphological species and fossil species were analyzed by Cluster Analysis,and the results showed that the shape of this species is still unique.Combined with the traditional method of naked-eye identification,it is confirmed that this species is a new fossil species,and named Trapa radiatiformis X.Wang&L.Xiao sp.nov..The results of R-type Cluster Analysis of extant species and fossil species showed that the width of fruit body was closely related to the height of fruit body.The results of Principal Component Analysis showed that the shape of fruit body,the width of core fruit body,the shape of top,the total number of large-angle,the number of the lower horns,the growth direction of lower horns,the length of lower horns and the number of tubercles were the guiding characters of identification and classification of extant species,while the results of Principal Component Analysis of fossil species showed that the height of whole fruit body,the width of whole fruit body,the length of the upper horns and the length of the lower horns were the guiding characters of the classification and identification of fossil species.Comparing the geographical distribution of the extant Trapa with that of the ancient Trapa,it is found that the geographical distribution of the ancient Trapa,is almost the same as that of the extant Trapa.Compared with the fruit morphology of Trapa in different ages,many of the earlier fruits have residual stalks and larger fruit bodies,with long and narrow upper horns and lower horns,obvious conical tubercles.With the passage of time,the residual stalk gradually disappeared,the fruit body became smaller,the upper horns,the lower horns and tubercles degenerated or disappeared.The feature of residual stalk shows the possibility that Hemitrapa is the ancestor of Trapa,but there are few species of Hemitrapa that can support this view and the fossil record is later,so the view that Hemitrapa and Trapa have the same ancestor is more convincing.Based on the previous studies on the DNA sequences of Trapa and Lythraceae,it was found that there is a close relationship between Lythrum and Trapa,but Lythrum growing on shore is older than Trapa.It is concluded that Trapa may grow first on land and migrate to water gradually over time.In this paper,the paleoclimate of the five layers is restored by using the method of Leaf Margin Analysis and Climate-Leaf Analysis Multivariate Program.The results show that the climate of Miocene in Zhejiang Province is very close to the modern climate.The Mean annual temperature of the five layers is 18.05?,16.03?,17.96?,16.57?,15.52?from old to new(CLAMP,Physa Asia2),which only shows an insignificant downward trend over time.Combined with the climate parameters and modern climate data obtained by predecessors,it is found that Difference in temperature between the coldest and warmest month(DT)and Mean annual precipitation(MAP)in modern times are slightly higher than that in late Miocene,which further indicates that the East Asian monsoon system has basically formed in late Miocene,and the monsoon effect is gradually significant over time.The global deep sea?¹⁸O curve also shows the global stable temperature in the late Miocene.Therefore,In addition to the influence of monsoon system,the prosperity of Trapa in late Miocene in Zhejiang is closely related to the stability of global climate.