Zhen & Nicoll: Canning Basin Serratognathus bilobatus Fauna 
13 
Drepanoistodus Lindstrom, 1971 
Type species. Oistodus forceps Lindstrom, 1955. 
Drepanoistodus sp. cf. Drepanoistodus nowlani 
Ji & Barnes, 1994 
Fig. 5G-P 
Drepanoistodus sp. cf. Drepanoistodus nowlani Ji & 
Barnes.—Zhen et al., 2007b: 132-134, pi. 2, figs 1-21, 
pi. 3, figs 1-9 ( cum syn.). 
Material. 52 specimens from three samples (Table 1). 
Remarks. The Emanuel specimens are comparable with 
those described from the Honghuayuan Formation of 
Guizhou as D. sp. cf. D. nowlani except for the less extended 
basal-anterior corner in the P elements (Fig. 5N-P). 
Fahraeusodus Stouge & Bagnoli, 1988 
Type species. ?Microzarkodina adentata McTavish, 1973. 
Fahraeusodus adentatus (McTavish, 1973) 
Fig. 6I-K, S-V 
?Microzarkodina adentata McTavish, 1973: 49, 50, pi. 3, 
figs 28, 33-35, 38-40, 42-44. 
Fahraeusodus adentatus (McTavish).—Stouge & Bagnoli, 
1988: 119, pi. 4, figs 12-14 (cum syn.); Lehnert, 1995:89, 
pi. 7, fig. 20A, 20B. 
Material. Seven specimens from two samples (Table 1). 
Remarks. Specimens representing the asymmetrical Sb 
element with a lateral costa on the outer lateral face (Fig. 6T), 
the strongly asymmetrical Sc element without a lateral costa 
on each side (Fig. 6S), and the asymmetrical Sd element with 
a costa on each side (Fig. 6U, V) were recovered in the two 
samples from the Emanuel Formation. A specimen represent¬ 
ing the triform Sa element with a broad, nearly flat anterior 
face and with a sharp anterolateral costa on each side (Fig. 
6I-K) is also assigned to this species. McTavish (1973) rec¬ 
ognized a quinquimembrate apparatus including oistodiform 
(= M element), ozarkodiniform (= P element), trichonodel- 
liform (= Sa element), cordylodiform (= Sc element), and 
tetraprioniodiform (= Sd element), and doubtfully assigned 
it to Microzarkodina. Stouge & Bagnoli (1988) proposed 
Fahraeusodus and selected ?M adentata as the type species. 
However, only a few specimens were recovered in the upper 
part of Bed 9 ( O. elegans Biozone) of the Cow Head Group in 
Newfoundland, an interval stratigraphically slightly younger 
than the occurrence in the Emanuel Formation. The flat 
anterior face and edge-like anterolateral costa on each side of 
the Sa element are comparable with some specimens referred 
to Fahraeusodus marathonensis by Stouge & Bagnoli (1988, 
e.g., pi. 4, fig. 15) from the Cow Head Group. 
Paracordylodus Lindstrom, 1955 
Type species. Paracordylodus gracilis Lindstrom, 1955. 
Paracordylodus gracilis Lindstrom, 1955 
Fig. 6A-F 
Oistodus gracilis Lindstrom, 1955: p. 576, pi. 5, figs 1-2. 
Paracordylodus gracilis Lindstrom, 1955: p. 584, pi. 6, figs 
11-12; Tolmacheva & Lofgren, 2000: 1117-1119, figs 5, 
7; Tolmacheva & Purnell, 2002: 209-228, text-figs 1-10; 
Zhen et al., 2004: p. 56, pi. 4, figs 19-22 {cum syn.). 
Material. 35 specimens from sample WCB705/243 (see 
Table 1). 
Remarks. Paracordylodus gracilis is one of the best known 
species in the Early Ordovician. The reconstructed apparatus 
initially was based on interpretation of collections of discrete 
specimens documented successively by Sweet & Bergstrom 
(1972), McTavish (1973), and van Wamel (1974). Their 
collective interpretations were confirmed nearly 30 years 
later by the in situ bedding plane assemblages (Tolmacheva 
& Lofgren, 2000; Tolmacheva & Purnell, 2002). Its species 
composition and structure based on numerous clusters from 
deep water radiolarian cherts in central Kazakhstan revealed 
important data about its evolutionary affinities (Tolmacheva 
& Purnell, 2002). Paracordylodus gracilis is widely dis¬ 
tributed (see Tolmacheva & Fofgren, 2000; Tolmacheva & 
Purnell, 2002), ranging from the late Tremadocian (late P. 
proteus Biozone) to late Floian (mid O. evae Biozone). It 
was most common in the Open Sea Realm (from shelf edge 
to basinal setting), with typical examples reported in central 
Kazakhstan (Tolmacheva & Purnell, 2002) occurring as 
the dominant species making up 90-99% of the specimen 
numbers. It is present in similar deep water oceanic settings 
in cherts of turbiditic successions (Percival et al., 2003), and 
also in allochthonous limestone or calcareous siltstone of 
slope settings (Zhen et al., 2004) in eastern Australia on the 
margins of eastern Gondwana. Paracordylodus gracilis was 
also common in the shallow marine environments within the 
Cold Domain of the Shallow-Sea Realm, such as in the Balto- 
Scandian Province (Fofgren, 1978; Tolmacheva & Fofgren, 
2000). Its occasional presence in outer shelf environments 
or more rarely in inner shelf habitats within Temperate or 
even Tropical domains can be attributed to up-welling of 
cold ocean currents. 
Par oistodus Lindstrom, 1971 
Type species. Oistodus parallelus Pander, 1856. 
Par oistodus parallelus (Pander, 1856) 
emend. Lofgren, 1997 
Fig. 7A-S 
Oistodus parallelus Pander, 1856: 27, pi. 2, fig. 40. 
Paroistodus parallelus (Pander).—Lindstrom, 1971: 47, 
fig. 8; Lofgren, 1997: 923-926, pi. 1, figs 1-12, 17, 21, 
text-fig. 5A-G ( cum syn.); Albanesi in Albanesi et al., 
1998: 144, pi. 8, figs 27-30; Johnston & Barnes, 2000: 
31-32, pi. 10, figs 10,11,15-17, 20; Tolmacheva et al., 
2001: fig. 4.12-4.13; Viira et al, 2006: pi. 1, fig. 5. 
