【作者】 欧强； 韩健； 张志飞； 舒德干； 孙舸； Georg Mayer；

【Author】 OU Qiang;HAN Jian;Zhifei Zhang;SHU Degan;SUN Ge;MAYER Georg;Early Life Evolution Laboratory,State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences;Department of Zoology,University of Kassel;Early Life Institute,Collaborative Innovation Center of Continental Tectonics,State Key Laboratory of Continental Dynamics,Northwest University;

【机构】 Early Life Evolution Laboratory,State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences； Department of Zoology,University of Kassel； Early Life Institute,Collaborative Innovation Center of Continental Tectonics,State Key Laboratory of Continental Dynamics,Northwest University；

【摘要】 The early Cambrian Problematica Xianguangia sinica,Chengjiangopenna wangii,and Galeaplumosus abilus from the Chengjiang biota(Yunnan,China) have caused much controversy in the past and their phylogenetic placements remain unresolved.Here we show,based on exceptionally preserved material(85 new specimens plus type material),that specimens previously assigned to these three species are in fact parts of the same organism and propose that C.wangii and G.abilus are junior synonyms of X.sinica.Our reconstruction of the complete animal reveals an extinct body plan that combines the characteristics of the three described species and is distinct from all known fossil and living taxa.This animal resembled a cnidarian polyp in overall morphology and having a gastric cavity partitioned by septum-like structures.However,it possessed an additional body cavity within its holdfast,an anchoring pit on the basal disc,and feather-like tentacles with densely-ciliated pinnules arranged in an alternating pattern,indicating that it was a suspension feeder rather than a predatory actiniarian.Phylogenetic analyses using Bayesian inference and maximum parsimony suggest that X.sinica is a stem-group cnidarian.This relationship implies that the last common ancestor of X.sinica and crown cnidarians was probably a benthic,polypoid animal with a partitioned gastric cavity and a single mouth/anus opening.This extinct body plan suggests that feeding strategies of stem cnidarians may have been drastically different from that of their crown relatives,which are almost exclusively predators,and reveals that the morphological disparity of total-group Cnidaria is greater than previously assumed.更多还原

【Abstract】 The early Cambrian Problematica Xianguangia sinica,Chengjiangopenna wangii,and Galeaplumosus abilus from the Chengjiang biota(Yunnan,China) have caused much controversy in the past and their phylogenetic placements remain unresolved.Here we show,based on exceptionally preserved material(85 new specimens plus type material),that specimens previously assigned to these three species are in fact parts of the same organism and propose that C.wangii and G.abilus are junior synonyms of X.sinica.Our reconstruction of the complete animal reveals an extinct body plan that combines the characteristics of the three described species and is distinct from all known fossil and living taxa.This animal resembled a cnidarian polyp in overall morphology and having a gastric cavity partitioned by septum-like structures.However,it possessed an additional body cavity within its holdfast,an anchoring pit on the basal disc,and feather-like tentacles with densely-ciliated pinnules arranged in an alternating pattern,indicating that it was a suspension feeder rather than a predatory actiniarian.Phylogenetic analyses using Bayesian inference and maximum parsimony suggest that X.sinica is a stem-group cnidarian.This relationship implies that the last common ancestor of X.sinica and crown cnidarians was probably a benthic,polypoid animal with a partitioned gastric cavity and a single mouth/anus opening.This extinct body plan suggests that feeding strategies of stem cnidarians may have been drastically different from that of their crown relatives,which are almost exclusively predators,and reveals that the morphological disparity of total-group Cnidaria is greater than previously assumed.更多还原