Algae From The Chengjiang Biota

The study on origin and early evolution of earth life has been an intriguing and enigmatic topic for centuries.The Chengjiang biota is one of the Burgess Shale-type biotas in the early Cambrian,documents many of the earliest representatives of zoophyla,which are significant to decipher the origin and evolution of early lives.Alga is the main biological group in the early geological history and an important part of early life.The main aim of this thesis is to investigate the algal fossils of the Chengjiang biota that were collected from Haikou Town and Chengjiang City.All algae have been examined by optical microscope and stereomicroscope.In order to distinguish the characteristics of morphology of algae,quantitative analysis is applied.Totally 10 genera and 12 species have been identified in the Chengjiang biota,including 1 new genus and 2 new species(e.g.,Yunnanospirellus typica gen.et sp.nov.Yunnanospirellus elegans gen.et sp.nov.).One undetermined species which is different from the undetermined species reported previously(Yuknessia sp.),six species that have been noted in other biotas(e.g.,Jiangchuan and Burgess Shale biotas),but not in the Chengjiang biota are identified(i.e.Liulingjitaenia alloplecta Chen and Xiao,1992,Longfengshania stipitate Du,1982,Longfengshania spheria Du and Tian,1986,Morania fragmenta Walcott,1919,Paralongfengshania sicyoides Du and Duan,1985,Tawuia danlensis Hofmann,1979).3 species that have been studied previously are reexamined and some morphological charcterisitics are amended or modified(e.g.,Sinocylindra yunnanensis Chen and Erdtmann,1991,Enteromophites intestinalis Xu,2001,Fuxianospira gyrata Chen and Zhou,1997).Statistical analysis indicates that 5 species(e.g.,Longfengshania stipitate Du,1982,Longfengshania spheria Du and Tian,1986,Paralongfengshania sicyoides Du and Duan,1985,Enteromophites intestinalis Xu,2001,Sinocylindra yunnanensis Chen and Erdtmann,1991)are benthic sessile algae which accounted for 42% in all algae species of the Chengjiang biota,and the rest are planktonic ones with predominately abundance.Comparative study indicates that the spiral fossils from the Chengjiang biota,exhibiting remarkable and chaotic variation in body width and spiral density,probably resulted from ambient turbulence in the process of taphonomy.Comparing with PreCambrian spiral algae,the early Cambrian Chengjiang ones increased in species diversity and abundance,as well as in geographic distribution.According to the abundant and the genus-level diversity comparison on benthic algae,it is proved that benthic algae dominated in the Ediacaran Jiangchuan biota,yet in the early Cambrian Chengjiang biota,planktonic algae bloomed and reigned supreme.