全 文 ：古生物学报 , 40(3):351-361(2001 年 7 月)
Acta Palaeontologica Sinica , 40(3):351-361(July , 2001)
桃曲坡牙形刺属(Taoqupognathus)在
澳大利亚及中国晚奥陶世的分布
甄勇毅
(澳大利亚博物馆地球和环境科学部 ,澳大利亚悉尼)
　　中文提要　Taoqupognathus为潘德尔刺类的一多分子器官属。其特征明显:单维 , 片状 , 具有不同发育程度的
后缘隆起。该属仅在澳大利亚东部和中国上奥陶统分布 , 已知有 4 种 , 而且具有较精确的区域对比价值。形态特
征的支序分析显示:在晚奥陶世中期(Eastonian), T.philipi-T.blandus-T.tumidus 谱系代表了该属的主要演
化趋向。 Taoqupognathus属的分布表明 ,澳大利亚东部和中国在当时有着密切的生物地理联系。该属可能在 Eas-
tonian早期起源于新南威尔世中部地区 ,在中-晚 Eastonian 期时达到发展高潮 , 并已扩散到中国各板块。继而可
能在 Eastonian 末期或 Bolindian 早期全部绝灭。
关键词　　牙形刺　生物地理　晚奥陶世　中国　澳大利亚
　　收稿日期:2000-12-29
DISTRIBUTION OF THE LATE ORDOVICIAN CONODONT TAOQUPOGNATHUS
IN EASTERN AUSTRALIA AND CHINA
ZHEN Yong-Yi
(Division of Earth and Environmental Sciences , The Austral ian Museum , 6 College Street , Sydney , nsn 2010 , Austral ia)
　　Abstract　 Taoqupognathus is a multimembrate panderodontid conodont , consisting of distinctive , blade-like , coni-
form elements with various degrees of posterior bulging.The genus is restricted in distribution to the Upper Ordovician of
eastern Australia and China , w here the four known species are useful for precise regional correlation.A cladistic analysis of
morphological characters indicates that the mian evolutionary trend of Taoqupognathus appears to follow the lineage:T .
philipi-T .blandus , and T .tumidus during the Eastonian(middle Late Ordovician), with T .philipi as the most primitive
form.The distribution of Taoqupognathus suggests a close biogeographical link between eastern Australia and China w ith the
genus apparently o riginating in central New South Wales in the early Eastonian.It then migrated to Chinese crustal blocks
during the summit of its development in the mid-late Eastonian , and probably became ex tinct in the latest Eastonian or early
Bolindian.
　　Key words　conodonts , biogeography , Late O rdovician , China , Aust ralia
INTRODUCTION
The genus Taoqupognathus was first recorded in the
Upper O rdovician of eastern Aust ralia in the 1970 s at
two localities:from limstone boulders within the Sofala
Volcanics of central New South Wales(Picket t , 1978),
and f rom the Fork Lagoons Beds of central Queensland
(Palmieri , 1978).Both occurrences were represented by
elements now known as the P elements of T.tumidus
T rotter and Webby , 1995.An(in An et al ., 1985)pro-
posed Taoqupognathus based on Chinese material with
T .blandus An , 1985 as the type species.Savage(1990)
described the T .philipi apparatus , the first multimem-
brate reconst ruction of the genus , f rom the lower part of
the Fossil Hill Limestone , Cliefden Caves area , cent ral
New South Wales.Trot ter and Webby (1995)described
the T .tumidus apparatus from limestone breccias of low-
er part of the Malongulli Formation from the same area.
Subsequently Zhen and Webby (1995)and Zhen et al .
(1999)revised the type species , T .blandus , in terms of
multimembrate terminology , based mainly on the cent ral
New South Wales material.Yu and Wang(1986)record-
ed a second Chinses species , T .beiguoshanensis , from
Longxian , Shaanxi Province , North China.The only fig-
ured specimen of Taoqupognathus ani Wang and Zhou ,
1998 from the T arim Basin , northwest China is identical
with the P element of T.tumidus from cent ral New
South Wales.Therefore , T .ani is herein regarded as a
junior synonym of T .tumidus.Thus only four valid
species have been are recognised , with T .philipi limited
to central New South Wales and T .beiguoshanensis re-
st ricted on the Ordos Basin of North China.The other
two species are widely distributed in eastern Australia and
China.Rapid evolution of the species in the Late Ordovi-
cian of these areas provides the taxa with considerable
biost ratigraphic utility.
　　The review of Taoqupognathus presented in this pa-
per aims to assist establishment of a useful Upper Ordovi-
cian conodont biostratig raphical zonal scheme for eastern
Australia.As Taoqupognathus is a distinctive genus en-
demic to eastern Australia and China , the dist ributional
patterns of its species should provide important data for
palaeobiogeographic analysis , and the Late O rdovician re-
construction of Gondwana.
CHARACTER EVOLUTION AND PHYLO-
　　GENETIC RELATIONSHIPS
　　Element associations of the various Taoqupognathus
species are poorly understood , and the notation schemes
proposed previously (Zhen et al ., 1999)are only a mat-
ter of convenience.So far neither bedding plane assem-
blage nor fused clusters of Taoqupognathus have been
found.The presently applied apparatus nomenclature is
based solely on discrete elements f rom central New South
Wales.The rations of composite element of the three
species from cent ral New South Wales are considerably out
of expected proportion.This might be due mainly to
taphonomic , depositional and post-depositioal processes af-
ter the death of conodont animals.For instance , the thin-
ner and slender M2 elements would have had much less
chance to be preserved in the carbonates , and then subse-
quently survive the acid leaching processing in the laborto-
ry.However , as indicated by Zhen and Webby (1995),
some of the defined element types are very rare and only
occur in one or two species.For instance , Zhen and Web-
by (1995)noted that Sc1 element of T .philipi might be
“ juveniles” or else a variant of Sc2 element.On the other
hand , the Sc4 element , only recorded in the T .tumidus
apparatus , seems comparable with the Sc3 element of T .
blandus.Logically this is likely , because Sc3 is the most
dominant element of the T .blandus apparatus.Rare
speciments identical with the Sc5 element of T .philipi
were also found in association with T.tumidus at the top
part of the Bowan Park G roup.A similar mixture of these
two species has also been found in the Wisemans Arm For-
mation of New England Fold Belt(Furey-Greig , 1999).
These data indicate that both T .philipi and T .blandus
might have been rare species , coexisting with their suc-
ceeding sister taxa in the mid-late Eastonian.
Tex t-fig.1　Data mat rix for the four species of Taoqupognathus
352 　　　　古　生　物　学　报 第 40卷
　　Taoqupognathus might be derived f rom Pandero-
dus.Both genera have a number of shared(synapomor-
phic)characters.Most importantly , both have a pan-
derodont furrow on one lateral face and a w rinkle zone of
st riations at the base.Based on these characters , Taoqu-
pognathus is placed in the Family Panderodontidae.How-
ever , in typical Panderodus , the wrinkle zone is much
weaker and poorly defined , while in Taoqupognathus ,
the wrinkle zone is well defined by a transverse ridge
crossing the lateral face from anterior margin to posterior
margin.All the elements of Taoqupognathus are blade-
like , st rongly compressed anterior-posteriorly with sharp
anterior and posterior margins.In cont rast , typical Pan-
derodus elements have a rather rounded anterior face , but
elements represented by Panderodus sp.(see Zhen et
al., 1999 , p.89)and some other genera of the family ,
like Belodina , do resemble Taoqupognathus in having
sharp anterior and posterior margins.Therefore , this is a
plesiomorphic character.The development of a transverse
ridge crossing the lateral faces antero-posteriorly near the
base forms the border of the basal wrinkle zone , and the
presence of posterior bulges are the two most important
autapomorphic characters defining the genus.T .philip i
is characterised by its elongated outline of the elements
and weakly developed posterior bulge.Both T.blandus
and T .tumidus have a prominent posterior bulge , even a
fin-like posterior bulge in some S elements.However ,
posterior bulges are more strongly developed and elements
are even shorter and stouter in T.tumidus(Text-fig.1).
The P elements of the latter are oval in outline , while the
P elements of T .blandus are more or less rectangular in
outline.Taoqupognathus beiguoshanensis from the upper
Beiguoshan Formation , Longxian , Shaanxi Province was
originally described and illustrated as a form species.
However , using the recent ly proposed notational system
(Zhen et al ., 1999)for the genus , two elements(Sb2 ?
and Sc5)can be recognised f rom the original illust ration.
Based on the figured Sc5 elements (Yu and Wang , 1986 ,
pl.1 , figs.6 , 10).T.beiguoshanensis is morphologically
closely related to T.tumidus.Both species have a fin-
like posterior bulge , but T .beiguoshanensis seems more
stout and short in outline.Detailed studies need to be car-
ried out in the type locality of T .beiguoshanensis to en-
able full recovery of the apparatus , which may prove that
T .beiguoshanensis is a senior synonym of T .tumidus.
At present , it seems clear that T .beiguoshanensis might
represent either a variation of the advanced stage of T .
tumidus , or a separate species derived f rom T .tumidus.
The evolutionary t rend of these species is clearly shown by
morphological changes in their corresponding elements.
More specifically , the S and P elements become shorter
and stouter , and their posterior bulges are more promi-
nent , f rom T .philipi to T .blandus and then to T .
tumidus (Zhen and Webby , 1995).
Text-f ig.2　Cladogram of fou r species of Taoqupognath us
wi th Panderodus sp.and Panderodus graci lis
as the outgroup
　　Zhen and Webby (1995)suggested that the three
Taoqupognathus species occurring in central New South
Wales might represent an evolving lineage.In order to
test this hypothesis , these species were analysed using
cladistic methods.Eleven characters with 27 character
states were coded(Text-fig.1)for four species of Taoqu-
pognathus , with Panderodus sp.and Panderodus gra-
cilis (Branson and Mehl , 1933)defined as the outg roup.
These characters are described as :
1.Panderodont furrow;o:absent , 1:present.
2.Fine longitudinal st riation on lateral surface;0:
absent;1:present.
3.Sharp anterior margin;0:absent , 1:present.
4.Sharp posterior margin;0:absent , 1:present.
5.Posterior margin of Sc5 element;0:smoothly
curved , 1:slightly convex , 2:prominently convex.
353第 3 期 甄勇毅:桃曲坡牙形刺属(Taoqupognathus)在澳大利亚及中国晚奥陶世的分布　　　　
6.Posterior margin of Sc2 element;0:smoothly
curved , 1:gently convex , 2:prominently convex.
7.Size of posterior bulge;0:absent , 1:small , 2:
prominent.
8.Fin-like posterior bulge;0:absent , 1:present.
9.Outline of posterior bulge of P element;0:absent
(no bulge), 1:concave , 2:straight-slightly convex , 3:
st rongly convex.
10.T ransverse ridge to define the w rinkle zone;0:
absent , 1:present.
11.Well-defined w rinkle zone;0:absent , 1:present.
By using parsimony analysis , with characters 5 , 6
and 9 as ordered and the rest as non ordered (PAUP
3.1), only one most parsimonious tree with a length of
13 steps was found(Text-fig.2 , CI=1;HI=0 , RI=1 ,
RC=1).The ing roup , consisting of the four species of
Taoqupognathus , forms a monophyletic group (Text-fig.
2).This result supports previously proposed (Zhen and
Webby , 1995)phylogenetic relationships within the genus
(Text-fig.3).
Text-fig.3　Inferred phylogeny and st ratigraphic dist ribut ion of Taoqupognath us
DISTRIBUTION AND CORRELATION OF
　　THE TAOQUPOGNATHUS FAUNAS
　　Based on studies of conodont faunas f rom cent ral
New South Wales , three successive conodont assemblage
zones , represented by three species of Taoqupognathus ,
can be recognised in eastern Aust ralia(Text-fig.3)within
the Eastonian.The oldest , the T.philipi assemblage
(Text-figs.3 , 4), spans most of the Fossil Hill Limestone
of central New South Wales (Zhen and Webby , 1995).
This assemblage was also reported from the lower Reedy
Creek Limestone , near Molong (Percival et al ., 1999),
and from allochthonous Late O rdovician limestone bodies
within the Late Silurian Barnby Hills Shate , north of Lar-
ras Lee(Farrell , 1996)of cent ral New South Wales.This
early Eastonian conodont fauna is preserved in a shallow
water facies with a relatively low diversity and a high ratio
of endemic forms , mainly represented by T.philipi ,
Aphelognathus percivali , A. packhami and A.
webbyi , T.philipi has not been reported occurring out-
side of NewSouth Wales.
The succeeding T .blandus assemblage ranges
through the upper Belubula Limestone and the Vandon
Limestone of the Cliefden Caves Limestone Group , and in
the lower-mid part of the Bowan Park G roup , in cent ral
New South Wales.It was also recorded from the upper
Reedy Creak Limestone(Percival et al .,1999), f rom al-
354 　　　　古　生　物　学　报 第 40卷
lochthonous limestone bodies within the Barnby Hills Shale
(Farrell , 1996), and f rom limestone boulders within the
Gunningbland Formation(Pickett and Percival , 2000).
Similar conodont assemblages characterised by the occur-
rence of T .blandus are widely distributed in China.T .
blandus has been reported occurring in the Upper Yao-
xian Formation and the lower part of the overlying Tao-
qupo Formation(mid Eastonian)in the O rdos Basin of the
North China Craton (An et al ., 1985;An and Zheng ,
1990), and in the lower part of the Sanjushan Formation
of Yushan , Jiangxi Province , southeast China(An ,
1987), from the Upper O rdovician Hongze Formation of
northern Jiangsu(Wang , 1993 , p.35), and the top Char-
chaq G roup of Kuruktag area of the Tarim Basin(Wang
and Zhou , 1998).The T aoqupo Formaiton(An et al .,
1985) is characterised by occurrences of T .blandus ,
Yaoxianognathus yaoxianensis , Y .? tunguskaensis , Phragmodus
Text-fig.4　Correlation of the Taoqupognath us faunas f rom eastern Aust ralia and North China
undatus , Belodina conf luens , Panderodus gracilis.
This assemblage is similar to that containing T.blandus
in central New South Wales.The Vandon Limestone and
its equivalents in central New South Wales are charac-
terised by the occurrence of a diverse coral fauna including
the first appearance of various species of Phasmoporella .
In the Yaoxian area of Shaanxi Province , Northwest Chi-
na , Plasmoporel la first appears near the base of the Tao-
qupo Formation (An et al ., 1985).The conodont and
coral associations therefore may suggest a correlation be-
tween the 226 m thick lower Taoqupo Formation in the
North China Craton and the upper Belubula-Vandon lime-
stones(mid Eastonian age)of cent rla New South Wales
(Text-fig.4).
An(1987)recognised two conodont assemblages in
the Sanjushan Formation , Xiazhen , Jiangxi Province ,
southeast China.The lower assemblage , bearing Taoqu-
pognathus blandus and Yaoxianognathus yaoxianensis
(mid Eastonian), was correlated with the lower part of
the Taoqupo Formation , Shaanxi Province.An (1987)
suggested that the lower boundary of the Sanjushan For-
mation is diachronous in Zhejiang and Jiangxi provinces.
The Sanjushan Formation of Jiangshan , Zhejiang Province
is only equivalent to the upper part(upper conodont assem-
blage , late Eastonian age)of the Sanjushan Formation in
the Xiazhen section , Yushan , Jiangxi Province.Lin and
Zou (1977)studied tabulate corals from the Sanjushan
Formation of this region.According to An (1987), T .
355第 3 期 甄勇毅:桃曲坡牙形刺属(Taoqupognathus)在澳大利亚及中国晚奥陶世的分布　　　　
blandus occurs in the rock Unit One and the lower to
middle part of rock Unit Two defined by Lin and Zou
(1977 , p.113).Unit One consists of 16.5 m of thick-
bedded limestone containing only fragmental brachiopods
and gastropods.The overlying Unit Two is 34.8 m fossil-
iferous , mid-thick bedded limestone and contains abundant
corals including Agetoli tes , Eof letcheria , Plasmoporel-
la , Heliolites , and Stelliporella , with Agetolites first oc-
curring at the middle part of this unit (Text-fig.2).A
similar coral fauna was also recorded from the Beiguoshan
Formation of the O rdos Basin of North China , in associa-
tion with T .beiguoshanensis(Yu andWang ,1986).This
correlation seems cont roversial.The occurrence of T .
blandus indicates a middle Eastonian age , while the corals
are typical late Eastonial to early Bolindian.Morphologi-
cally , the only figured specimen of T .blandus from the
Sanjushan Formation(An , 1987 , pl.30 , fig.20)is compa-
rable with the Sc3 element of T .blandus(see Zhen and
Webby , 1995 , pl.6 , fig.1)and with the Sc4 element of
T .tumidus of late Eastonian age.As discussed earlier ,
these elements of the two species are very close.There-
fore , this problem can only be resolved by further detailed
conodont studies of the Sanjushan Formation , a carbonate
succession of 1 534 m in total thickness.
The youngest T .tumidus assemblage seems much
more widely dist ributed than the two older Taoqupog-
nathus assemblages in eastern Australia (Text-fig.5).
This assemblage , characterised by the occurrence of T .
tumidus with a st rong posterior bulge , has been reported
from various localities of New South Wales and Queens-
land.These localities are:limestone clasts of the lower
Malongulli Formation(T rotter andWebby , 1995), the top
Bowan Park Group and basal Malachis Hill Formation
(Zhen et al ., 1999), the upper Weemalla Formation of
the Junction Reef area , Cadia(Packham et al., 1999),
limestones within the Gunningbland Formation (Picket t
and Percival , 2000), and limestone boulders of the Sofala
Volcanics(Pickett , 1978;Percival et al ., 1999)of cen-
tral New South Wales;limestone lenses in the U ralba
Beds(Gillies , 1994;Furey-Greig , 2000)and the Wise-
mans Arm Formation(Furey-Greig , 1999)of New Eng-
land Fold Belt;Fork Lagoon Beds of east-central Queens-
land(Palmieri , 1978), and the Carrier s Well Limestone
of north Queensland(Simpson , 2000).Other fossils asso-
ciated with this assemblage are corals including the ru-
gosan Favistina and tabulate Plasmoporel la .In the
Cliefden Caves area , the assemblage is associated with
graptolite fauna of late Eastonian(Ea3)age (Trot te and
Webby , 1995).
In China , T .tumidus is only confirmed to occur in
the Upper Ordovician Hongze Formation (Duam , 1990)
of South China and from the top part of the U ligeshitag
G roup of Kuruktag region of the Tarim Basin (Wang and
Zhou , 1998).No characteristic conodonts have been re-
ported from the upper Taoqupo Formation(67 m thick)of
the Ordos Basin , although the rugosan Favist ina was
recorded from this level(Text-fig.2).This is important
for correlation , because in New South Wales , the first ap-
pearance of Fav istina occurs in limestone breccias of the
lower part of the Malongulli Formation(Webby , 1998),
which also yielded the conodont T .tumidus assemblage.
This suggests a correlation of the lower Malongulli Forma-
tion with the upper part of the T aoqupo Formation of
Shaanxi , North China.This correlation is further sup-
ported by the occurrence of T .beiguoshanensis from the
the Beiguoshan Formation , Longxian , Shannxi Province
(about 180 km to the west of Yaoxian).
Taoqupognathus beiguoshanensis , the youngest of
the four species , and as yet not adequately described and
illustrated , makes detailed comparison with New South
Wales material difficult.However , the figured specimens
of Yu and Wang (1986)show a close resemblance to T .
tumidus from eastern Australia.At the type locality , the
formation consists of a 400 m-thick limestone succession
with corals , brachiopods , t rilobites and conodonts.This
conodont datum indicates that the Beiguoshan Formation
bearing T .beiguoshanensis at its upper part should be
slightly younger than the level of limestone breccias of the
Malongulli Formation of cent ral New South Wales.The
associated coral assemblage of mainly Agetoli tes sp.,
Plasmoporel la sp., Heliolites sp., and Catenipora sp.
in the Beiguoshan Formation(Yu and Wang , 1986)also
supports this correlation.In eastern Australia , Agetolites
was reported from the Carrier s Well Limestone of north
Queesland(Hill et al ., 1969), and f rom the Angullong
Formation of central New South Wales (Pogson and
watkins , 1998 , p.373).Simpson(2000)also reported the
occurrence of T .tumidus in the Carrier s Well Limestone
of north Queensland.The occurrence of Amorphognathus
ordovicicus in the Carrier s Well Limestone suggested
356 　　　　古　生　物　学　报 第 40卷
that this unit may well extend to the Bolindian(Simpson ,
1997).The macrofauna from the Carrie s Well Lime-
stone also indicates a Late Ordovician age(Webby et al .,
1981;Withnall and Lang , 1993).However , detailed
biost ratigraphy of this unit is pending upon further con-
odont study.
BIOGEOGRAPHIC IMPLICATIONS
The Gondw ana supercontinent w as initiated
probably during the Cambrian , when its eastern part
drif ted aw ay from Laurentia(Dalziel ,1991;Li et al.,
1993).Palaeomagnetic data mainly accumulated in
the last twenty years have provided useful lati tudinal
const raints on the palaeogeog raphical reconst ruction of
the Early Palaeozoic Australian cont inent(McElhinny
et al., 1974;Schmidt and Mo rris , 1977;Goleby ,
1980;Li et al.,1990;Li et al., 1993 , Li and Pow ell
in press).All of these data , along w ith the palaeon-
tologic and palaeoclimatic data , imply that most of
Aust ralia was in the tropical , equato rial zone in the
Ordovician wi th the Late Ordovician equator probably
crossing Australia along the southeast near Perth.
China is a much mo re complicated collage , as it
w as fo rmed by the amalgamation of a number of tec-
tonic blocks , composite terranes or remnants and
their surrounding fold belts.Palaeomagnetic data
from North and South China blocks (Lin et al.,
1985;Zhao et al.,1992;Nie ,1991)suggested a low
latitudinal position in or close to the equatorial zone
for bo th North and South China during the Ordovi-
cian.However , Late Ordovician longi tudinal posi-
tions of Australia , North China , South China , and
the Tarim Basin , as w ell as thei r relative positions ,
have been reconstructed quite differently by various
palaeogeographic researchers.
Close biogeog raphic relationships between North
China , South China , and Australia during Cambrian
and Early Ordovician(Burrett and Richardson ,1980;
S tait and Burrett , 1987;Nicoll , 1989;Burrett et
al., 1990;Cocks and Fortey , 1990)suggested that
both North and South China w ere part of Gondw ana ,
in close proximity to Aust ralia.The palaeomagnetic
data , mainly f rom the Yang zi Platfo rm(western part
of South China)and the sedimentolog ical and biologi-
cal informat ion suggested that South China w as in a
low latitudinal position in the Early Palaeozoic(Li et
al., 1993).I t remained as part of Gondw ana until
the Late Silurian or Early Devonian(Nie ,1991;Met-
calfe ,1992).No palaeomagnetic data are available for
No rth China f rom the Late Ordovician to Early Car-
boniferous , since most of No rth China w as uplif ted
and experienced a long period of erosion during this
time interval.However at its w estern margin , a re-
gion lies along the w estern and southw estern edges of
the Ordos Basin , the deposition extends to the Late
Ordovician.The Yaoxian Fo rmation , Taoqupo For-
mation , and Beiguoshan Formation in the Shaanxi
Province represent the carbonate dominated Upper
Ordovician succession of this region.Althouth there
have been lit tle palaeomagnetic data f rom the Upper
Ordovician of this region , a close zoogeog raphical
aff inity is demonst rated by the distribution of the con-
odonts , Taoqupognathus , Y aoxianognathus and
Tasmanognathus , and some corals.This indicates
that North China was still adjacent to Aust ralia dur-
ing the Late Ordovician.
Sco tese and McKerrow(1991)reposi tio ned both
the North and South China blocks to the northwest of
Gondw ana.Differing from these Ordovician recon-
struct ions , Li et al.(1993)associated North China to
the northeast of Gondw ana , close to Tasmania , and
linked South China to the no rthw est of Gondwana ad-
jacent to Western Aust ralia.In thei r recently updated
Late Ordovician reconst ruction(Li and Pow ell , in
press), South China , North China and Tarim are sit-
uated to the w est of Australia wi thin the t ropical to
subtropical zone and also w ithin the same longi tudinal
zone.South China is situated in the middle with the
equator crossing the eastern part , w ith the Tarim
Block to i ts South and North China to it s north at a
similar distance(Tex t-f ig .5).Dist ribution of Taoqu-
pognathus is plot ted on this Late Ordovician base
map , which show s that the genus had a distribut ion
limited to northwest margins of Gondw ana.
357第 3 期 甄勇毅:桃曲坡牙形刺属(Taoqupognathus)在澳大利亚及中国晚奥陶世的分布　　　　
　　The Eastonian conodont faunas of eastern Australia ,
characterised by Taoqupognathus and Yaoxianognathus ,
show close zoological affinities with contemporaneous fau-
nas recovered from the southwestern margin of the North
China Craton , from South China , and f rom the Tarim
Basin.These two endemic genera appear to have originat-
ed in cent ral New South Wales prior to migration else-
where.Based on these links , Nowlan et al .(1997)pro-
posed a Late O rdovician“Aust ralasian Province”.Recent
studies of Early O rdovician(Bendigonian)conodonts show
that theAustralasian Province existed in the Early Ordovi-
cian and remained distinctive through Middle and Late Or-
dovician time(Zhen et al ., in press).However most of
the Eastonian index zonal conodont species established for
the North A tlantic Province and the North American Mid-
continent Province have either a relatively long st rati-
graphic range or a st rongly const rained biofacies dist ribu-
tion.Therefore precise correlation of eastern Australian
Eastonian conodont faunas with those established in these
two provinces remains dif ficult.
Text-fig.5　Distribution of Taoqupognath us An , 1985 , in eastern
Australia and C hina , and a Late Ordovician palaeo-
geographic reconstruction of eastern Gondw ana , 450
Ma , near the base of the Eastonian(modified f rom Li　
　　　　　and Pow ell , in press)
Occurrences of the Taoqupognathus conodont assem-
blage in the Upper O rdovician of the Lower Yangzi region
indicate close biogeographic links between South China
and North China , coral , graptolite and cephalopod faunas
from the Upper O rdovician of the western margin of
North China Craton also show similarities to those of
Lower Yangzi Valley.However , in the Early to Middle
O rdovician , shallow water carbonates of shelly facies were
dominant in most of the North China Craton and faunal
differences were distinctive between North and South Chi-
na(Lai , 1982).Finney and Chen(1990)suggested a cold
northeast-flowing current to influence distribution of the
cooler water faunas in the low latitudinal Yangzi Platform
of South China.
Abundant occurrence of various species of Belodina
also indicates a close biogeographic links between the Aus-
tralasian Province and the North American Midcontinent
Province.In the latter , the last appearance of Belodina
compressa(Branson and Mehl , 1933)and the first appear-
ance of B.conf luens defined the lower boundary of the
Belodina conf luens Biozone.The upper boundary of this
zone was defined by the first appearance of Oulodus veli-
cuspis(Pulse and Sweet , 1960).This lower boundary of
the conf luens Biozone appears not to have been recoginsed
either in eastern Aust ralia or in China.First , all speci-
ments previously ascribed to B.compressa from eastern
Australia are now referrable to B.conf luens(Sweet in
Ziegler , 1991;Zhen and Webby , 1995), except for mate-
rial from the Wahringa Limestone Member of the Fair-
bridge Vollcanics in central New South Wales(Percival et
al., 1999).This latter material is under further exami-
naiton(Zhen et al ., in prep.).Secondly , Late Ordovi-
cian conodont faunas in New South Wales are overw helm-
ingly dominated by various Belodina species , eg.nearly
40%of the total recovered conodont fauna from the Clief-
den Caves Limestone G roup (Zhen and Webby , 1995),
and nearly 20% of the total recovered conodont fauna
from the Bowan Park succession (Zhen et al ., 1999).
According to Sweet(1979), the stratig raphically older
(late Gisbornian), and senior species , B.compressa can
only be distinguished from B.conf luens by the flattened
anterobasal corner of the compressiform element on its in-
ner face.Large collection of B .conf luens from cent ral
New South Wales shows a fairly wide range of variation
within the species.
The eastern Aust ralian Gisbornian conodont faunas
have not yet been studied in detail , and the st ratigraphic
relationship of t hese two species of Belodina in Australia
is yet to be recognised.Distinction of these two species
(based on a relatively small number of specimens from the
North American Midcontinent)is yet to be further tested
358 　　　　古　生　物　学　报 第 40卷
in eastern Australia , China , and other closely related re-
gions as well.In these regions Belodina is apparent ly
much more abundant and shows g reater diversity and vari-
ation than in North America , where Belodina conf luens
succeeds B.compressa stratigraphically and was probably
derived f rom the latter(Sweet in Ziegler , 1991).Fur-
thermore , there are two conodont biozones(undatus and
tenuis biozones)between the compressa and the conf lu-
ens biozones in the North American Midcontinent zona-
tion.Unfortunately , both of these zonal species have a
relatively long stratigraphic range and their dist ributions
are confined to relatively deeper water biofacies.Although
both B.compressa and B.conf luens have been recorded
occurring in various localities in China , they do not show
the st ratigraphical order as demonstrated in North Ameri-
ca.They are often reported occurring in the same st rati-
graphical levels or even with B.compressa overlying B.
conf luens(Yu and Wang , 1986;Fu et al ., 1993;Wnag
and Zhou , 1998).These observaitons st rongly suggest the
necessity of re-evaluating the species definition of both B.
compressa and B.conf luens in order to justify the sepa-
ration of B.conf luens.
Based on the palaeontological data , Stait and Burret t
(1987)and Burrett et al.(1990)indicated a strong bio-
geographic tie between North China and eastern Australia
during the O rdovician.This relationship is also supported
by the conodont data from both regions , whose faunas are
dominated by coniform species.More specifically , the
Late O rdovician conodont faunas f rom both regions are
characterised by abundant occurrence of various species of
Belodina and the presence of Taoqupognathus , Yaoxi-
anognathus and Tasmanognathus.This inferred biogeo-
graphic relationship is also supported by the Late Ordovi-
cian coral and st romatoporoid data(Webby et al., 1997).
The coral Agetolites is widely distributed in the Upper
O rdovician of South China , western margin of the North
China Craton , Qilian Fold Belt , and Junggar.Favistina ,
a rugosan coral genus of probable Siberia-North American
origin , is abundant in the Upper Ordovician of the North
China Carton and Qilian Fold Belt , but is absent from
South China.Taking account of the relatively common oc-
currence of Favistina and rare occurrence of Agetolites in
the Upper O rdovician of eastern Australia , it appears that
North China Craton had closer biogeographic links with
eastern Australia.Like the North China Craton , most of
the Tarim Platform was uplifted in the Late O rdovician
(late Eastonian to Bolindian).The Upper O rdovician ,
dominated by carbonate deposits was only developed in the
northern and northeastern margin of the platform (Zhou
and Lin , 1995).A similar kind of uplifting during the
Late O rdovician was also widely developed in the Aus-
tralian cratonic regions(Webby et al ., 1981;Webby et
al., in press).Globally , there was a significant eustatic
sea level rise during the Late O rdovician (Barnes et al .,
1996).Uplift of these large crustal blocks during the Late
O rdovician may represent a significant regional tectonic
event , and the shared tectonic set ting is also important ev-
idence to support a close geographic link between these
crustal blocks during the Late O rdovician.
ACKNOWLEDGMENTS
This paper is a contribution to the global O rdovician
biodiversity project , IGCP P roject No.410.The research
benefited f rom a t ravel grant provided by the exchange
prog ram between the Australian Academy of Sciences and
the Chinese Academy of Sciences which enabled the author
to visit Nanjing Institu te of Geology and Palaeontology ,
Chinese Academy of Sciences and Peking University in
late 2000.Drs G.D.Edgecombe and I.G.Percival kindly
read the manuscript and made constructive suggestions.
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