Morphological Classification And Paleoecological Characteristics Of Coelophysis In The Cambrian Kaili Biota, Guizho

The only representative of uncertain affinities among basal animals,chancelloriids,occurred in some Konservat-Lagerst?tten and small shelly fossils,which date to Cambrian Terreneuvian to Miaolingian.Therefore,research on chancelloriids will shed light on exploring the cause of the "Cambrian explosion" and revealing the complex Cambrian ecosystems.Chancelloriids accounts for only a few in the total biomass of Kaili biota,but it packs a very powerful punch of diversity.A total of 25 complete individuals are assigned to 3 genera,6 species,including 2 new species,3 known species and 1 indeterminate species: Chancelloria zhaoi sp.nov.、Chancelloria eros Walcott,1920、Archiasterella anchoriformis sp.nov.、Allonnia erjiensis Yun et al.,2018;Allonnia phrixothrix Bengtson and Hou,2001;Allonnia sp.,all belonging to the Family Chancelloriidae Walcott,1920.The newly described species are different from previously reported types in that C.zhaoi has 5+1C and 6+1C sclerites with bilateral symmetry,the length of rays in the same sclerite is significantly different and apical tuft conspicuous;Ar.anchoriformis with large angle between lateral rays(3+1A)and an identifiable apical tuft.C.zhaoi、C.eros and Ar.anchoriformis represent the all exceptionally preserved chancelloriid species of Chancelloria and Archiasterella in the Kaili Biota,as well as South China.In the meantime,the presently available literatures suggest that the chancelloriids were continuous distributions in the Cambrian strata of South China from Fortunian to the Guzhangian,this study concluded two flourishing ages of chancelloriids: 1)Late Stage 2 to Stage 3.As typified by Chengjiang Biota,all chancelloriids except Eremactis have appeared and expanded rapidly in this period;2)Cambrian Wuliuan.Also called“Renaissance”,the diversity of chancelloriids in this age was obviously lower than those of flourishing age 1,Cambrothyra and Niderlric became extinct Wuliuan ago,while the fossil associations of this phase has improved significantly than those of Stage4,Kaili Biota is a vital Konservat-Lagerst?tten of chancelloriids.This study also investigates the burial mode of chancelloriids in Kaili Biota and their ecological features.Major conclusions include: Combining with the preservation of chancelloriids and the sedimentary environment of Kaili Biota,suggesting a in situ preservation.SEM-EDX analysis shows variable preservation of carbonaceous compression and pyritization of chancelloriids.As one of the epibenthic suspensionfeeding animals,the lower part of the body displays a stalk structure or missing of early Cambrian due to sticking into the muddy substrate,while the study area and Burgess Shale during middle Cambrian reveal evidence that chancelloriids are attached via the hard and mineralized animals to substrate,which shows that such animals unable to adapt to the changes of “Cambrian Substrate Revolution”.All phenomena suggest that chancelloriids takes tight-growth pattern as the survival strategy and not limited to specific types.