PROGRESS IN NATURAL SCIENCE Vo l .13 , No .11 , November 2003

Early Cambrian eodiscoid trilobites of the Yangtze Platform and their stratigraphic implications＊

YANG Aihua , ZH U Maoy an＊＊ , ZHANG Junming and LI Guoxiang

(Nanjing Institute of Geology and Palaeontology , Chinese Academy of S ciences, Nanjing 210008 , China)

Received June 6 , 2003 ;revised June 16 , 2003

Abstract Analysis of the taxonomy and stratigraphic distribution of the Early Cambrian eodiscoid trilobites of the Yangtze Plat- form indicates that species of Tsunyid iscus and Hupeidiscus can be used for biostratigraphic correlation .T .aclis occurs only in the lower Qiongzhusian, T .armatus occurs in the low er and middle Qiongzhusian , w hile T .niu titangensis and T .tingi occu r mainly in the middle and upper Qiongzhusian , w ith only T .tingi extending upw ard into the low er Canglangpuian .H .orienta lis first appears in the upper Qiongzhusian , reaching peak abundance in the lower Canglangpuian and becoming extinct above the Drepanuroides Zone .Biostrati- graphic and lithostratigraphic correlations indicate that the limestone in the low er part of the Mingxinsi Formation , the Upper M ember of Jiumenchong Formation , and the upper part of the Middle Member of the Huangbailing Formation , can be correlated with each other as Huped iscus, an index fossil of the low er Canglangpuian, is abundant in all these units.The low er part of the Niutitang and Jiumenchong formations in eastern Guizhou , w hich mainly represent Qiongzhusian strata, can be correlated with the Low er Member of the Huangbail- ing Formation .The basal part of the Niutitang Formation , w hich may be equivalent to the Upper Meishucunian Shiyantou Formation in eastern Yunnan , is very condensed .Well-preserved sponge faunas and non-mineralized fossils in the lower part of the Niutitang and Het- ang formations are not older than Qiongzhusian in age.

Keywords: eodiscoids, trilobites, black shale, stratigraphy, Early Cambrian, Yangtze Platform, South China .

Lower Cambrian black shales are w ell developed 1 Synopsis of stratigraphic sections in the transitional region of the Yang tze Platform . How ever , because of the rarity of index fossils, sub- 1 .1 Eastern Guizhou Province division and stratigraphic correlation of these shales Longshancun section:This section is located at remain controversial[ 1 ～ 6] .Eodiscoid trilobites are Yonghe , Weng' an County , Guizhou Province (Fig .1 abundant in certain parts of the black shales , but ④).Here the Neoproterozoic-Low er Cambrian se- trilobite specialists are in disagreement over the tax- quence is well exposed .The Lower Cambrian succession onomy and stratigraphic distribution of these fossils . Consequently , the usefulness of these trilobites to the correlation of the Lower Cambrian black shales of the Yang tze Platform and beyond has been limited .

Based on the results of recent investigations on the Niutitang and Jiumenchong fo rmations of eastern Guizhou Province and the Huangboling Formation of southern Anhui Province , we here revise the taxono- my and clarify the stratig raphic distribution of the Lower Cambrian eodiscoids of the Yangtze Platform . In addition , w e use these fossils to develop a new set of stratig raphic correlations of the Lower Cambrian black shales .

Fig .1 . Geographic maps show ing the locations of investigated sections, note the section numbers are the same as in Fig .2 .

＊ Supported by the National Natu ral Science Foundation of China (Grant Nos.40232020 and 40172002), the Chinese Ministry of Science and Technology (Grant No .GT 2000077700) ＊＊ To w hom correspondence should be addressed .E-mail:myzhu @nigpas.ac .cn 862 Progress in Natu ral Science Vol.13 No .11 2003

consists (in ascending o rder ) of the Niutitang , the Niutitang Form ation (the lowest occurrence of M ingx insi and Jinding shan formations .The Niuti- this trilobite is 16 .8 m above the Dengying tang Formation is composed of black shales and dis- dolomite).The Ming xinsi Formation , w hich consists conformably overlies the upper dolomite member of mainly of limestone with trilobites and archaeocy- the Dengy ing Formation .Tsunyidiscus niutitangen- athids , conform ably overlies the Niutitang Formation sis has been found in the lower and middle parts of (Fig .2(4)).

Fig.2 . Stratig raphic correlations of the Low er Cambrian black shales of South C hina (fossil occu rrences in each section are based on our own new data).1 , dolomite ;2 , limestone w ith intercalations of black shale ;3 , silicastone;4 , carbonaceous mudstone;5 , siltstone and mudstone;6 , siliceous m udstone ;7 , limestone ;8 , carbonaceous shale;9, black shale ;10 , carbonaceous silty mudstone ;11 , siltstone; 12 , phosphatic dolomite;13 , interbeds of siliceous siltstone and muddy siltstone ;14 , muddy limestone ;15 , mudstone;16 , carbonaceous siltstone;17 , Middle Devonian ;18 , fault;19 , barite ;20 , siliceous siltstone;21 , phosphatic dolomitic concretions;22 , phosphatic con- cretions;23 , stone coal;24 , limestone concretions;25 , spicule;26 , rhabdopleurids;27 , complete sponges;28 , bivalved arthropods. (1)Meishucun section , Jinning County , Yunnan ;(2)Gezhongw u section , Zhijin County , Guizhou ;(3)Songlin section , Zunyi County , Guizhou ;(4)Longshancun section , W eng' an County , Guizhou ;(5)Huanglian section , Songtao County , Guizhou ;(6)Wuhe section , Taijiang County , Guizhou ;(7)Pangw angcun section , Dongzhi County , Anhui;(8)Lantian section , Xiuning Coun ty , Anhui;(9)Wu- jialing section , Jiangshan County , Zhejiang .

Huanglian section:This section is located on the (Sphenothallus)15 m above the base of the forma- eastern limb of the dissected Songtao Anticline (Fig .1 tion .The upper member consists of dark gray argilla- ⑤).Here the Lower Cambrian successions are well ceous limestone w ith trilobites , including Hupeidis- exposed and consist of the (uppermost Proterozoic) cus sp ., Sinodiscus changyangensis and Metared- Liuchapo and the basal Cambrian Jiumenchong , Bian- lichia sp .[ 7] (Fig .2(5)). machong , Balang and Qingshudong formations[ 7] . The Jiumenchong Formation conformably overlies the Wuhe section:This section is exposed along the Liuchapo Fo rmation , w hich consists of black silicol- Qingshui River from Wuhe to Gedong , Taijiang County , ites (cherts)and phosphatic siliceous shales .The Jiu- Guizhou Province (Fig .1 ⑥).The Lower Cambrian suc- menchong Fo rmation is subdivided into tw o mem- cession consists of the Liuchapo , Jiumenchong , Bianma- bers .The low er member consists of black shale yield- chong , Balang and Tsinghsutung formations.The litholo- ing bivalved arthropods (Sunella)and tubular fossils gy of the Jiumenchong Formation is similar to that of the Progress in Natural Science Vol.13 No .11 2003 863 same formation in the section at Huanglian .Hupeidiscus occur in the limestone at the topmost part of the Jiumen- orientalis (Fig .3(a), (b))and Hsǜaspis guizhougensis chong Formation (Fig .2(6)).

Fig.3 . (a)～ (c)Hupeidiscus orientalis (Chang , 1953).(a), (b)from the upper part of the Jiumenchong Formation in the Wuhe sec- tion near Taijiang County , Guizhou , (c)from the base of Bianmachong Formation in Bageng section near Taijiang County , Guizhou ;(a) cranidium , GT VI-14 ;b .pygidium , GT VI-15 .(c)cranidium , GTV-1b .(d), (e) Tsu nyidiscus niu titangensis (Chang , 1966)from the Niutitang Formation in the Longshancun section near Weng' an County , Guizhou ;(d)cranidium , WDc-6 ;(e)pygidium , W Dc-5 . (f), (g), (h)Tsunyid iscus armatus (Zhang et Zhu , 1980), from the Niutitang Formation in the Longshancun section near Weng' an County , Guizhou ;(f) cranidium WDc-13 ;(g)pygidium W Dc-15 ;(h)exoskeleton , W Dc-16 , ×15 .(i) Tsunyidiscus aclis Zhou , 1975 , from the base of the “ black shale unit” of Yu' anshan Formation, pygidium (by Steiner et al., 2001).

1 .2 Southern Anhui Province Lantian section :This section is located in north- eastern Xiuning County (Fig .1 ⑧).The Piyuancun Pangwangcun section:This section is located in Formation is similar lithologically to rocks in the southeastern Jianxin , Do ngzhi County , w here it is Pangw angcun section .The Hetang Form ation con- exposed along the road from Pangw ang Village to formably overlies the upper member of the Piyuancun Do ngzhi County Town (Fig .1 ⑦).The section starts Formation , the lower part of w hich consists of about in the Piy uancun Fo rmation .Succeeding strata con- 20 m of “ algal stone coals” containing complete sist of the Huang boling Formation and the lower part sponges (Fig .2(8)). of the Yang liugang Formation .The upper member of the Piy uancun Formation is composed of about 23 m 2 Taxonomic revision and stratigraphic dis- of siliceous sandstone w ith intercalations of carbona- tribution of Early Cambrian eodiscoids ceous shale .In addition , lenticular limestone beds oc- cur in the basal part of this member .The Huangbol- To date , 12 genera and 51 species of eodiscoids ing Formation consists of three members .The low er have been reported and described from the Early member is composed of about 32 m of “alg al stone Cambrian of the Yang tze Platform .Again , how ever , coal” and black carbonaceous shale containing sponge the taxonomy of these fossils is controversial[ 8～ 11] . spicules .The middle member , about 40 m thick , The most recent investigation , based on published contains limestones w ith H upeidiscus orientalis .The type specimens and new material, revealed that only lower part of the upper member is composed of about seven eodiscoid genera are valid (for detailed discus- 130 m of black carbonaceous m udstone containing sions see Master thesis of Yang Aihua1)).Mo reover , complete spo nges ;the upper part of this member con- only four of the 32 published species of Tsunyidisccus sists of about 377 m of g ray silty mudstone y ielding are valid .These four species are T .niutitangensis the trilobites Cheiruroides prim igenius Chang and Chang , 1966 , T .aclis Zhou , 1975 , T .armatus Redlichia (Pterored lichia)chinensis Walcott (Fig .2 (Zhang et Zhu), 1980 and T .tingi (Lu), 1974 . (7)). Hupeidiscus orientalis Chang , 1974 is the sole

1)Yang A .H .Eodiscoids and stratigraphy of Early Cambrian black shales in eastern Guizhou and southern Anhui.Unpublished Master' s thesis, Nanjing Institute of Geology and Palaeontology , 2002 , 1 ～ 91 . 864 Progress in Natu ral Science Vol.13 No .11 2003 species of its genus ;the other seven described species are junior sy nonyms of the ty pe species .Because of 2 .4 Tsunyidiscus tingi (Lu , 1942) page limitatio n , here w e only give diag nosis of these This species w as first described and illustrated by five species and their stratigraphic distribution . Lu[ 14] .It differs from the other three species in hav- 2 .1 Tsunyidiscus aclis Zhou , 1975 ing five pairs of pleural furrow s on the m ature py gidi- um . T . tingi generally occurs in the upper Emended diagnosis:Cephalon semi-elliptical in Qio ngzhusian but may ex tend into the lower outline ;g labella convex and narrow , divided into Canglang puian in Jingding shan , Guizhou Province[ 14] three lobes by very faint , broad , shallow transglabel- (Fig .4). lar furrow s ;occipital ring extending posterio rly into a [ 15] stout spine ;anterior border broad , w ith about ten 2 .5 Hupeidiscus orientalis (Chang , 1953) sm all bosses arranged in a regular pattern ;postero- Emended diagnosis :Do rsal exoskeleton elongate lateral limb ex tending posterolaterally into a long and elliptical in outline .Glabella convex , narrow , coni- stout genal spine ;eye lines long and narrow .Pygidi- cal , w ith tw o faint transglabellar o r discontinuous um semicircular in outline , with five to six pairs of glabellar furrow s ;anterior border narrow and w ithout pleural furrows ;axial posterior tip reaching the bor- bosses;palpebral lobes narrow ;eye lines long and der furrow ;stout axial spine present on the posterio r narrow ;genal spines present or absent .Tho rax com- [ 12] axial tip (Fig .3(i)). posed of three segments .Pygidium semi-elliptical in outline ;axial lobe convex , narrow or stout , w ith 3 Stratigraphic distribution :T .aclis occurs only segments and three axial tubercles on the axial lobe ; in the basal part of the Wutingaspis-Eoredlichia In- pleural region without pleural furrows , finely g ranu- terval Zone (Fig .4). lated (Fig .3(a),(b), (c)). 2 .2 Tsunyidiscus armatus (Zhang et Zhu , 1980) Stratigraphic distribution:This species general- Emended diagnosis :Do rsal exoskeleton elliptical ly occurs in the upper part of the Yunnanocephalus in outline .Glabella convex , narrow , divided by two Assemblage Subzone of the Qiongzhusian Stage , and very shallow transglabellar furrow s ;occipital ring ex- is abundant in the Drepanuroides zone of the tending backw ard into a sm all spine ;bo rder furrow Canglang puian Stage (Fig .4). broad and deep ;border broad , slightly convex , with bosses ;eye lines clear .Thorax w ith three segments . Pygidium semi-elliptical in outline ;py gidial axis ele- vated ;pleural fields smoo th (Fig .3 (f), (g), (h)).

Stratigraphic distribution:This species first oc- curs in the basal part of the Wutingaspis-Eoredlichia Interval Zone and ex tends into the middle of the Wutingaspis-Eored lichia Interval Zone (Fig .4).

2 .3 Tsuny idiscus niutitangensis ( Chang , 1966)[ 13]

Emended diagnosis :Glabella extremely narrow , Fig .4 . Stratigraphic distribution of Tsunyidiscus and Hupeidis- ex tending anteriorly to the border furrow ;occipital cus . ring extending posteriorly into a small spine ;posteri- or margin of the cranidium with prominent or faint 3 Stratigraphic implications geniculation .Thorax com posed of three segments . M ature pygidium bears four pairs of pleural furrow s ; The relatively short stratig raphic ranges of Tsunyidiscus and Hupeidiscus (Fig .4)make these axial lobe faintly seg mented ;axial posterior tip does eodiscoids potentially useful for stratigraphic co rrela- not reach the border furrow (Fig .3(d), (e)). tion of the Lower Cambrian black shales of the Stratigraphic distribution :This species occurs Yangtze Platform .In eastern Yunnan Province , T . mainly in strata of middle and late Qiongzhusian age . aclis and T .niutitangensis first appear at the lower Progress in Natural Science Vol.13 No .11 2003 865 part of Wutingaspis-Eoredlichia Interval Zone of the section.Additionally , the lower parts of these units Qiong zhusian Stage[ 16 ～ 18] (Fig .2).T .niutitangesis contain so-called “ rhabdopleurids ” or colonial occurs about 10 m above the base of the Niutitang monopodial “ hydrozoans .” Thus , the low er part of Formation in the Gezhongw u section , indicating that the Jiumenchong Fo rmation may be equivalent to the the lower part of the Niutitang Formation belong s the Niutitang Fo rmation , although w e do not have bios- middle-upper Qiongzhusian S tage .In addition , small tratig raphic evidence to confirm this correlation .Nev- shelly fossils from the upper member of the Gezhong- ertheless , a distinct and widely distributed phosphatic w u Formation in this section belong in the concretion horizon , generally present at the base of S iphogonuchites-Halkieria Assemblage-Zone , sug- the Jiumenchong and Niutitang formations , can po- gesting that most of the Meishucunian Stage is miss- tentially be used as a marker bed for regional co rrela- ing and thus that the boundary between the Niutitang tion (Fig .2).This is because the phosphatic nodules and Gezhongw u fo rmations is a majo r unconfo rmi- at the base of Early Cam brian black shale occur in [ 19 ～ 21] ty .Although sm all shelly fossils have not been nearly all facies of the Yang tze Platform , indicating found in the basal part of the Niutitang Fo rmation in that this ho rizon represents the beginning of a trans- the Song ling section , the Fe-Ni-M o-rich layer , w hich gressive event w hich generally occurred no later than occurs at the base of the Qiongzhusian in eastern the early Qiongzhusian , and may have started during [ 16] Yunnan (Meishucun section in Jinning and sec- the late Meishucunian (from the base of the Shiy an- tions in Dezhe , Qujing)and at the base of the Niuti- tou Formation to the base of the Yu' anshan Forma- [ 22] tang Formation in the Gezhongw u and Songlin tion in eastern Yunnan). sections of Guizhou[ 3] , can be used as a marker bed for regional correlation .The correlatio ns above sug- Because of the common occurrence of H .orien- gest that only the basal part of the Niutitang Form a- talis , the upper part of the middle member of the tion in Guizhou represents the upper part of the Huangboling Formatio n in the Pangw angcun section M eishucunian Stage .The middle and upper parts of in S Anhui may correlate w ith the upper part of the the Niutitang Formation can be assigned at least to Early Canglangpuian Jiumenchong Fo rmation in the the Qiongzhusian Stage on the basis of the occurrence Wuhe section in Guizhou .In addition , the upper of T .nititangensis (5 m above the Fe-Ni-M o ore member of the Huangboling Form ation contains layer in the Song lin section , see Fig .2).Therefore , Cheiruroides primigenius Chang and Redlichia the age of the Zuny i biota is Qiongzhusian , equivalent (Pteroredlichia) chinensis Walcott , bo th of w hich to that of the Chengjiang biota in o ther facies . are common in the Mantou Formation (Longwang- miaoian)of the North China Plate[ 9] .This fact fur- The occurrence of T .niutitangesis about 10 m ther supports the conclusion that the upper part of the above the base of the Niutitang Form ation in the middle member of the Huangboling Formation be- Long shancun section indicates that the low er part of longs in the Canglangpuian Stage .According ly , the the Niutitang Fo rmation can also be placed in the low er member of the Huangboling Formation may be- middle-upper Qiong zhusian Stage .The lower part of long in the Qiong zhusian Stage .A “Stone Coal” hori- the Ming xinsi Fo rmation , with Hupeidiscus and zon at the base of the Huangboling and Hetang forma- Metaredlichia , may belong in the lower Canglang- tions in S Anhui can be used as a m arker bed fo r the puian Stage , as Metaredlichia first occurs in the low- boundary betw een the Qioanzhusian and Meishucuni- er Cang langpuian Stage[ 2] .These correlations suggest an stages .This is because the “Stone Coal” horizon at that the m ajor part of the Niutitang Form ation in NW the base of the Qiong zhusian occurs throughout the and SW Guizhou is equivalent in age to the Yu' an- shan Formation in Yunnan . Yangtze Platform (Fig .2).However , the sequences in the Hetang Formation in Zhejiang Province are Because of their similar trilobite records , the complex ;they are well developed in certain sections limestone at the top of the Jiumenchong Formation in such as the Diben section in Kaihua County , w hile in the Huanglian and Wuhe sections can be correlated other sections (e .g ., the Wujialing Sectio n in Jiang- w ith the low er part of the Ming xinsi Formation in the shan County[ 23 , 24] ) the Hetang Formation uncon- Long shancun section , suggesting that these lime- formably overlies the Denying Formation (Fig .2). stones are Canglangpuian in age .The low er part of Therefore , the sections of the Hetang Fo rmation in S the Jiumencho ng Fo rmation is very similar lithologi- Anhui and Zhejiang provinces are chronostrati- cally to the Niutitang Fo rmation in the Longshancun graphically different , and integ rated approaches to 866 Progress in Natu ral Science Vol.13 No .11 2003 their detailed co rrelation are required (Fig .2). 8 Zhang , S .G .Eodiscina.In :Cambrian trilobite faunas of south- w estern China (ed .Chang W .T .et al.).Palaeontologia Sinica , 4 Conclusions whole number 159 , New S eries B .Beijing :Science Press, 1980 , No .16 :1 ～ 497 . Bio- and lithostratigraphic correlations indicate 9 Chang , W .T .et al.Cambrian trilobites of north China .Beijing : that the limestone bed in the lower part of the Science Press, 1987 , 46 ～ 47 . M ingx insi Formation , the Upper Member of the Jiu- 10 Chang, W .T .World' s oldest Camb rian trilobites from eastern menchong Fo rmation , and the upper part of the Mid- Yunnan, In :S tratigraphy and Palaeontology of systemic bound- aries in China, Precambrian-Cambrian boundary (ed .Chang W . dle Member of the Huangboling Fo rmation are mutu- T .).Nanjing :Nanjing University Publishing House, 1987 , 1 :1 ally equivalent and also early Cang langpuian in age . ～ 17 . The lower part of the Niutitang and Jiumenchong for- 11 Jell, P .A .Suborder Eodiscina .In :T reatise on Invertebrate Pale- mations in E Guizhou , w hich mainly represent ontology (ed .W hittington , H .B .et al.), Part O , Arth ropoda 1 , Qiong zhusian strata , may be co rrelated with the Trilobita, Revised .Boulder, Colorado and Law rence , Kansas: Lower Member of the Huangboling Fo rmation .The The Geological Society of America, Inc.and the University of basal part of the Niutitang Formation , w hich m ay be Kansas, 1997 , 384 ～ 404 . equivalent to the Upper Meishucunian Shiyantou For- 12 Li , Y .X .et al.Early Palaeozoic stratig raphy of w estern part of mation in eastern Yunnan , is very condensed .Ex- Dabashan .Beijing , C hina :Geological Publishing House , 1975 , 1 traordinarily w ell preserved sponge faunas and non- ～ 372 . 13 Chang , W .T .On the classification of Redlichiacea, w ith descrip- mineralized fossils in the low er part of the Niutitang tion of new families and new genera.Acta Palaeontologica Sinica , and Hetang formations generally are no t older than 1966 , 14(2):135 . the Qiongzhusian (Fig .2). 14 Lu , Y .H .Some low er Cambrian trilobites from Chintingshan , N Acknowledgement Assistance in the field w as provided by KueiC hou .Bulletin of the Geological Society of China, 1942 , 22(3 He Ho ngw ei , Q i Dunlun , and Zhu Xuejian.T he authors thank ～ 4):177 . Z hou Zhiyi , Peng Shanci and Yuan Jinliang , Qian Yi , Bernd 15 Chang , W .T .Some low er Cambrian trilobites from w estern Hu- D .Erdtmann and Michael Steiner for fruitful discussions of this pei.Acta Palaeontological Society of China, 1953 , 24 :111 . w ork .The English w as impro ved by Heyo V an Iten . 16 Luo , H .L .et al.Stratotype section for lower Cambrian stages in China (in Chinese w ith English abstract).Kunming :Yunnan Sci- References ence and Technology Press, 1994 . 17 Steiner , M .et al.The Low er Cambrian of eastern Yunnan :trilo- 1 Zhao , Y.L.et al.Discovery and significance of the early metazoan bite-based biostratigraphy and related faunas.In :The Cambrian of biotas from the Low er Cambrian Niutitang Formation , Zunyi, South C hina (ed .Zhu , M .Y.et al.), Acta Palaeontologica Sini- Guizhou , China.Acta Palaeontologica Sinica, 1999 , 38(Sup .): ca, 2001 , 40(supp .):63 . 132 . 18 Zhu , M .Y .et al.Early Cambrian S tratigraphy of Eastern Yun- 2 Yuan , J.L.et al.Subdivision and correlation of Low er Cambrian nan, S outhwestern China:A S ynthesis.In :The Cambrian of in Southw est China, w ith a discussion of the age of Early Cambrian South C hina (ed .Zhu , M .Y.et al.), Acta Palaeontologica Sini- series biota.Acta Palaeontologica Sinica, 1999 , 38 (S up .):116 . ca, 2001 , 40(supp .):1 . 3 Steiner , M .et al.Submarine-hydrothermal exhalative ore layers in 19 Qian , Y .et al.S mall shelly fossils from the low er Cambrian in black shales from South China and associated fossils—insights in to a Guizhou.Professional Paper of Stratig raphy and Palaeontology , Lower Camb rian facies and bio-evolution . Palaeogeography , Beijing :Geological Publishing House , 1984 , 13 :91 ～ 123 . Palaeoclimatology , Palaeoecology , 2001 , 169 :165 . 20 Qian, Y .et al.Taxonomy and Biostratigraphy of Small S helly 4 Erdtmann , B .-D .et al.S pecial observations concerning the Sini- Fossils in China (in Chinese with English abstract).Beijing :Sci- an- Camb rian transition and its stratigraphic implications on the ence Press, 1999 . central and SW Yangtze Platform , China .Palaeow orld , 2001 , 13 21 Zhu , M .Y .Sinian-C ambrian boundary stratigraphy at Gezhong- (Sup .):52 . wu , Zhijin County , Guizhou Province, China :Phosphorite and 5 Wu , Y.D.Sequence stratigraphy of Cambrian in Dongzhi Coun- Small shelly fossils.Palaeoworld , 2001 , 13 :209 . ty , Anhui Province, China.Journal of Palaeogeography , 2001 , 3 22 Wang , X .G .et al.The upper Precambrian and Sinian-Camb rian (3):55 . boundary in Guizhou (in Chinese with English abstract).Guiyang : 6 Yuan, X.L.et al.Tow ering sponges in an Early Cambrian The People' s Publishing House of Guizhou , 1984 . Lagerstätte :Disparity betw een nonbilaterian epifaunal tierers at the 23 Yue , Z.et al.Early Cambrian Conodonts and Bradoriids from Neoproterozoic-Camb rian transition .Geology , 2002 , 30(4):363 . Zhejiang.Acta Micropalaeontologica Sinica, 1989 , 6(3):289 . 7 Zhao , Y .L.et al.Cambrian stratig raphy at Huanglian , Guizhou 24 Steiner , M .et al.A Low er Cambrian Small Shelly Fauna from Province, C hina:reference section for bases of the Nangaoan and Zhejiang (China)and its biostratigraphical implication .Progress in Duyun stages.In :Cambrian system of S outh China (ed .Peng , S . Natu ral Science, 2003 , 13(11):852 . C .et al.), Palaeow orld , 2001 , 13(Sup .):172 .