安徽滁州琅琊山下奥陶统弗洛阶(红花园组上部)的苔藓动物(英文)

FLOAN(EARLY ORDOVICIAN)BRYOZOANS FROM THE UPPER HUNGHUAYUAN FORMATION OF LANGYASHAN,CHUZHOU,ANHUI PROVINCE,CHINA

寒武纪没有化石苔藓动物的任何记录。最老的、毫无疑问的、真正的苔藓动物,发现于我国峡东地区的下奥陶统特马豆克阶地层中。这类苔藓动物以丰富但多样性低的变口目和少量的隐口目为代表。弗洛期的一些苔藓动物,在北美、英国和波罗的海地区(俄罗斯西北部)已相继发现,这时以Ceramopora unapensis为代表的泡孔目苔藓动物开始出现,有一定的多样性。中奥陶世初期,苔藓动物迅速崛起,古生代狭唇纲的四个目---变口目、隐口目、泡孔目和管孔目(=环口目)苔藓动物都已经有了代表。由于奥陶纪是苔藓动物发生、演化发展和辐射的重要时期,因此,奥陶纪,特别是早奥陶世苔藓动物的任何新的发现,都有重要的意义。本文描述和解释的一个新的苔藓动物群,发现于安徽滁州琅琊山弗洛阶的红花园组上部。这个苔藓动物群由变口目爱沙尼亚苔虫亚目的两个种:Dianulites hexaporites(Pander),Orbiramus grandissp.nov.和隐口目翼网苔虫亚目的一个种:Prophyllodi-ctya putilovensisLavrentjeva组成。尽管这个苔藓动物群在局部地区可能还是低多样性的,但就整个世界范围而言,有一定的多样性,类似于同样以变口目苔藓动物占优势的比林根苔藓动物群,后一苔藓动物群产于波罗的海以东地区(俄罗斯西北部)同时代的地层中。

In the Cambrian there were no fossil bryozoans found anywhere in the world. The oldest unequivocal bryozoans, which are representative of abundant trepostomes and rare cryptostomes, occurred in the late Tremadocian of east Yangtze Gorges in China. Some Floan bryozoans are discovered in North America, Britain and Baltic districts （northwestern Russia） with moderate diversity, where cystoporates represented by Cerarnopora？ unapensis make their first appearances. During the early Middle Ordovician, bryozoans rapidly evolved and radiated, with four Paleozoic stenolaemate orders [trepostomes, cryptostomes, cystoporates and tubuliporates （= cyclostomes）] being established. Because the Ordovician is an important period of the origin, evolution and radiation of the bryozoans, any new discovery of bryozoans, especially in the Early Ordovician, is significant for bryozoologists. A new bryofauna is reported here from the upper part of the Hunghuayuan Formation of the Floan Stage of Langyashan, Chuzhou, Anhui in China. It comprises two species, Dianulites hexaporites （Pander）, Orbirarnus grandis sp. nov. of trepostome esthonioporines, and one species, Prophyllodictya putilovensis Lavrentjeva of cryptostome ptilodictyines. Although the bryofauna is relatively of lower diversity in this area, as compared with other bryofaunas in the world, it is quite simi- lar to that of the Billingen, which is also dominated by trepostomes, from coeval strata of northwestern Russia （East Baltic）.