Fossil Fruit Of Trapa L.from The Miocene In Eastern Zhejiang And Its Paleoenvironment

This thesis researched some fossil fruits of Trapa L. which were found in the Miocene of second deposition layer of the Shengxian Formation, Ninghai, Zhejiang Province. The species bears the features,4 horns,4 tubercles and absent of corona. Those characters are different from known species of Trapa L., so it can be described as a new species of the genus Trapa L., T. ninghaica Xiaodong Lv &Bainian Sun sp. nov.. Based on the section is composed of silty mudstone and the living environment of existing Trapa, this species probably inhabited in lakes and ponds with low-energy and eutrophic environment. According to the development from flower to fruit and the morphological differentiation during the process, a cluster analysis has been carried out. In the analysis, a close relation-ship has been noted among T. ninghaica, T. chengsenii and T. srodoniana. They may descended from one ancestor. Finally, the thesis introduced the distribution and geological distribution of Trapa L. in the world and China,then discussed the factors which affecting the distribution and the significance of angiosperms evolution.