36 
S. McLoughlin 
Brongniart 1825. Several specimens from the 
Bullsbrook Formation also display variable 
dissection but differ from Nilssonia species herein 
which show distinct gaps between lamina 
segments (pinnules). 
Incertae sedis 
Pinnate frond 
Figure 6D 
Material 
UWA10475. 
Distribution 
Bullsbrook Formation (Neocomian-Barremian), 
Perth Basin, Western Australia. 
Description 
A single poorly preserved pinnate frond of 
uncertain affinities occurs in the Bullsbrook 
Formation assemblage. Frond 4 cm long, 2.2 cm 
wide, base and apex absent. Rachis broad (3 mm), 
longitudinally striate, gently tapering distally; 
pinnules linear with full basal attachment, margins 
entire or gently undulate, venation indistinct 
(Figure 6D). 
Remarks 
This specimen may represent a fern, seed-fern, or 
cycadophyte frond. The apparently undulate 
margins on some pinnules invite comparison to 
Douglas's (1969) Pachypteris austropapillosa 
recorded from coeval "Zone B" floras of the 
Victorian Early Cretaceous but the specimen is too 
poorly preserved for identification. 
Division Cycadophyta 
Order Bennettitales 
Genus Nilssonia Brongniart, 1825 
Type species 
Nilssonia brews Brongniart, 1825; Rhaetian; Hoer, 
Sweden. 
Nilssonia sp. A 
Figure 7F 
1993 Nilssonia sp. A; McLoughlin and Guppy; p. 
14; figure 15. 
Material 
WAM P.96.3. 
Distribution 
Nanutarra Formation (Neocomian-?Aptian), 
Carnarvon Basin. 
Description 
Fragmentary pinnate fronds with broad striate 
rachis (<5 mm wide). Pinnules subopposite, 
truncate elliptical, semicircular, oblong, or slightly 
falcate, up to 15 mm wide and 25 mm long; apex 
rounded, asymmetrical; full basal attachment; 
inserted laterally? or adaxially? on rachis (Figure 
7F). Pinnule bases expanded slightly, basiscopic 
margin rounded convex, acroscopic margin 
straight or slightly concave. Generally >10 veins 
arising from pinnule base, each bifurcates no more 
than twice (rarely more than once), passing sub¬ 
parallel to apical and lateral margins without 
anastomoses. 
Comments 
The full basal insertion of pinnules on the rachis 
distinguishes this leaf-form from Otozamites species 
which have pinnules with contracted bases (Taylor 
and Taylor 1993). White's (1961b) Pterophyllum 
fissum Feistmantel leaves are pinnatifid in contrast 
to the pinnate Nilssonia sp. A. Several Nilssonia and 
Ctenozamites species from the Yorkshire Jurassic 
(Harris 1964) have similar sized fronds to the 
Western Australian examples but differ in the 
details of their pinnule shapes and venation. 
Nilssonia sp. B 
Figure 7B 
1993 Nilssonia sp. B; McLoughlin and Guppy; p. 14; 
figure 17. 
Material 
WAM P.88.5, WAM P.88.6. 
Distribution 
Broome Sandstone (Neocomian-Barremian), 
Canning Basin. 
Description 
Fragmentary elliptical to oblanceolate pinnate 
fronds, petiolate; rachis up to 2 mm wide. Pinnules 
with full basal attachment, semicircular to oblong, 
apex rounded. Basiscopic margin of pinnules 
gently convex, acroscopic margin straight or 
slightly concave (Figure 7B). Pinnules alternate, up 
to 12 mm wide, 22 mm long. Numerous closely 
spaced, fine, indistinct, veins emerge from rachis, 
diverge gently towards apex and lateral margins; 
bifurcations rare, anastomoses absent. 
Comments 
This leaf form differs from Nilssonia sp. A by its 
more divergent and closely spaced venation. 
White's (1961a) and Walkom's (1919a) Nilssonia 
schaumbergensis Dunker from the Broome 
Sandstone and Burrum Coal Measures respectively 
