6 
Records of the Australian Museum (2009) Vol. 61 
elegans Biozone) is characterized by abundant P. adami in 
association with Bergstroemognathus extensus, Drepanodus 
arcuatus, Paroistodus parallelus, P. proteus, Paracordylodus 
gracilis, Tropodus australis, Protopanderodus gradatus, and 
Protoprioniodus simplicissimus, all of which are also present 
in the Emanuel Formation. According to Stouge & Bagnoli 
(1988, figs 3,4), both O. communis and P. elegans first appear 
at a similar level in the upper part (not top) of Bed 9 and define 
the boundary of the P. adami/P. elegans biozones in the upper 
part of Bed 9. Both P proteus and P. parallelus make their first 
appearance near the base of Bed 9 of the Cow Head Group, 
about three m below the first appearance of P. adami. 
The first appearance (FAD) of Tetragraptus approximatus 
is the primary marker defining the base of the Floian Stage 
(Bergstrom et al., 2004). In the Diabasbrottet GSSP Section 
at Hunneberg, southwestern Sweden, the Tremadocian/ 
Floian boundary was defined by the FAD of T approximatus, 
2.1 m above the top of the Cambrian, and the lower part of 
the T. approximatus graptolite Biozone was correlated to the 
topmost subzone ( Oelandodus alongatus-Acodus deltatus 
deltatus Subzone) of the P. proteus conodont Biozone (see 
Bergstrom et al., 2004, fig. 10). Therefore, the FAD of T. 
approximatus near the base (3m above the base at the Fedge 
Section) of Bed 9 in the Cow Head Group (Williams et al., 
1999) suggests that the P. adami Biozone in Newfoundland 
should be correlated with the upper part of the P. proteus 
Biozone ( Oelandodus alongatus-Acodus deltatus deltatus 
Subzone) of the Balto-Scandian succession. 
The P. adami-S. bilobatus Biozone is proposed herein 
to represent the fauna from the middle to upper part of the 
Emanuel Formation. It is characterized by the occurrence of 
P. adami, S. bilobatus, Paroistodus proteus, P. parallelus and 
other species listed in Table 1, with its base defined by the 
first appearance of S. bilobatus from the middle member of 
the Emanuel Formation and the upper boundary defined by 
the first appearance of O. communis in the basal part of the 
Gap Creek Formation (Nicoll & Ethington, 2004). It can be 
confidently correlated with the P. adami Biozone in the lower 
part of Bed 9 of the Cow Head Group in Newfoundland, with 
the Oelandodus alongatus-Acodus deltatus deltatus Subzone 
of the P. proteus Biozone (possibly also lowest P. elegans 
Biozone) of the Balto-Scandian conodont succession, with the 
S. diversus Biozone in the Honghuayuan Formation of South 
China, and with the S. bilobatus and S. extensus biozones in 
the Fiangjiashan Formation of North China (Fig. 2). 
Biogeographic distribution of Serratognathus 
The morphologically distinctive conodont Serratognathus 
is widely distributed in Fower Ordovician (lower Floian) 
rocks in China (South China, North China Platform, Ordos 
Basin, Tarim Basin and southern Hainan Island), Korea, 
Malaysia, and Australia (Arafura Basin and Canning 
Basin). Among the three species assigned to the genus ( S. 
bilobatus Fee, 1970, S. diversus An, 1981, and S. extensus 
Yang in An et al., 1983), S. bilobatus has a relatively wider 
geographic distribution (Fig. 3) occurring in the Dumugol 
Formation of South Korea (Fee, 1970), in the Fiangjiashan 
Formation of North China Platform (An et al., 1983), in the 
Qianzhongliangzi Formation of the Ordos Basin in North 
China (An & Zheng, 1990), in the Honghuayuan Formation 
of South China (An et al., 1983; Ding et al. in Wang, 
1993), in the upper part of the Dakui Formation of Sanya, 
Hainan Island (Wang et al., 1996), in the lower part of the 
Setul Fimestone in Malaysia (Metcalfe, 1980, 2004), in the 
Mooroongga Formation (subsurface) of the Arafura Basin 
off the north coast of Australia (Nicoll unpublished material), 
and in the Emanuel Formation of the Canning Basin, Western 
Australia (this study). Zhylkaidarov (1998, p. 65) indicated 
the occurrence of S. bilobatus from the Shabakty Formation 
in Malyi Karatau of southern Kazakhstan. However, as 
neither illustrations nor other information of the species 
from this locality are available, this Kazakhstan occurrence 
is considered doubtful at present. Serratognathus diversus 
is recorded in the Honghuayuan Formation and coeval units 
in South China (An et al., 1985; An, 1987; Zhen et al., in 
press a), Fiangjiashan Formation of North China (An et al., 
1983), and the upper subgroup of the Qiulitag Group of the 
Tarim Basin (Zhao et al., 2000). Serratognathus extensus, 
possibly representing the most advanced of the three species, 
has been reported only from the Fiangjiashan Formation of 
North China Platform (An et al., 1983). 
The type material of S. bilobatus was described from the 
Dumugol Formation in the Taebaeksan Basin in the central- 
eastern part of the Korean Peninsula (Fee, 1970; Choi et al., 
2005). The Dumugol Formation (also called the Dumugol 
Shale) consists of shale and intercalated limestone whose 
thickness varies from 150 to 270 m across the region and 
contains cyclic successions shifting from the near-shore to 
the deeper subtidal facies on a low-relief carbonate shelf, 
which was believed to be part of an extension of the North 
China Platform during the Early Ordovician (Choi et al., 
2001,2005). It yielded abundant conodont and trilobite faunas 
closely comparable to the late Tremadocian to early Floian 
faunas of North China (Fee, 1970, 1975; An et al., 1983; 
Zhou & Fortey, 1986; Seo et al, 1994; Choi et al., 2005). 
Occurrence of the Archaeoscyphia-Calathium association 
(occasionally forming isolated bioherms) in the Dumugol 
Formation also supports a close biogeographic link with 
North China (Choi et al., 2005). Based on rich and diverse 
conodont assemblages, Seo et al. (1994) divided the Dumugol 
Formation into four conodont biozones (in ascending order): 
Chosonodina herfurthi-Rossodus manitouensis Biozone, 
Colaptoconus quadraplicatus Biozone, Paracordylodus 
gracilis Biozone, and Triangulodus dumugolensis Biozone, 
with an age ranging from late Tremadocian to early Floian. 
They correlated the Triangulodus dumugolensis Biozone at 
the top of the Formation to the S. bilobatus Biozone of North 
China, but unfortunately S. bilobatus was not recovered from 
any of their studied samples, and the type horizon of this 
species described by Fee (1970) in the region was not pinned 
down in their new biostratigraphic scheme of the Dumugol 
Formation. However, Seo et al. (1994, p. 606) indicated that 
S. bilobatus also occurs in the overlying Maggol Formation 
as reported in two unpublished postgraduate theses. 
In North China, S. bilobatus was widely reported as 
occurring in the Fiangjiashan Formation within an interval 
correlated to the upper P. proteus Biozone to lower P. 
elegans Biozone of the Balto-Scandian conodont succes¬ 
sion (Zhen et al., in press a). The Fiangjiashan Formation is 
best exposed in the Zhaogezhuang Section near Tangshan, 
Hebei Province, where it consists of a 160 m sequence 
of a thick-bedded lower limestone member and an upper 
dolomite member (Chen Xu et al., 1995) that conform¬ 
ably overlies the Yeli (Yehli) Formation of Tremadocian 
age and is overlain by the Beianzhuang Formation of the 
