56 
S. McLoughlin 
conifers, which are comparable to Western 
Australian taxa, and has been assigned an Early 
Cretaceous (probable Hauterivian-Barremian) age 
(Archangelsky 1976; Baldoni 1979, 1980c; Baldoni 
and Taylor 1983). 
Macrofloras from the South African Kirkwood, 
Mngazana, and Makatini Formations range from 
Berriasian to late Aptian in age and are represented 
by Marchanlites, Ricciopsis, Cladophlebis, 
Sphenopteris, Onychiopsis, Taeniopteris, Pseudoctenis, 
Zamites, Dictyozamites, Araucaria, and Podocarpus 
species (Anderson and Anderson 1985). Most of 
these are readily distinguishable from Australian 
forms, a few are shared with South American 
assemblages but the majority appear to be endemic 
to South Africa suggesting an early floristic 
separation of this province from other Gondwanan 
regions. 
The upper Fossil Bluff Formation flora 
(Barremian-Albian) of Alexander Island, 
Antarctica, contains Hausrnannia, Cladophlebis, 
Taeniopteris, and Elatocladus species comparable to 
those in the Western Australian assemblages but 
differs in its possession of ginkgophytes, 
Pagiophyllum, Bellarinea, and Phlebopteris. The upper 
Fossil Bluff Formation floras correspond more 
closely with the Victorian Zone C assemblages. The 
Hope and Botany Bay floras of the Antarctic 
Peninsula were originally regarded as Jurassic in 
age (Halle 1913). Later studies suggested an Early 
Cretaceous age (Francis 1986; Gee 1989) based on 
an abundance of sphenopterid, cladophleboid, 
taeniopterid, bennettitalean, and podocarpacean 
remains similar to other Gondwanan Early 
Cretaceous assemblages. However, these Antarctic 
assemblages are characterized by the presence of 
possible sagenopterid pteridosperms and 
Goeppertella favouring an Early Jurassic age (Rees 
1993). 
Comparisons with extra-Gondwanan floras 
Many plant families have wide, often 
cosmopolitan, distributions in the Jurassic, 
however, by Early Cretaceous times fragmentation 
of Pangaea led to renewed floral provincialism 
equivalent to that of the late Palaeozoic (Meyen 
1987). Although some families and genera 
maintained wide distributions in the Early 
Cretaceous, Gondwanan floras are readily 
distinguishable from those of other provinces at 
species (and often genus) level. Geographically, the 
closest extra-Gondwanan landmasses to Australia 
during the Early Cretaceous were probably the 
series of disjunct terranes presently constituting 
South China, Indochina, and Malesia (Audley- 
Charles 1988; Metcalfe 1991). Although Mesozoic 
floras have been reported from these areas (Kimura 
and Ohana 1992), many have not yet been fully 
documented. Late Jurassic and Early Cretaceous 
floras of Japan are distinguished from Australian 
floras by the presence of, or greater representation 
of, bennettitalean taxa such as Zamites, Neozamites, 
Anomozamites, Dictyozamites, Ctenozamites, 
cycadaleans (such as Ctenis), czekanowskialeans, 
and conifers including Podozamites, 
Cupressinocladus, and Frenelopsis (Kimura and 
Ohana 1987a,b,c, 1992, 1988, 1989; Kimura et al. 
1985, 1991, 1992). Malayan and Thai mid- to late 
Mesozoic floras (Kon'no 1967, 1972; Smiley 1970; 
Kon'no and Asama 1975; Asama et al. 1981) and 
coeval Indochinese macrofloras (Serra 1963, 1966; 
Vozenin-Serra 1977) have affinities with other 
southern (Ryoseki-type) east Asian floras (Kimura 
1987, 1988) and have few if any elements in 
common with Australian assemblages. 
Palaeoenvironments and palaeoclimates 
The presence of high latitude forests and 
terrestrial vertebrate populations together with 
oxygen isotope signatures from marine 
invertebrates suggest globally raised temperatures 
during the Early and mid-Cretaceous (Frakes 1979; 
Douglas and Williams 1982; Barron 1983; Spicer 
and Parish 1986; Rich and Rich 1989; Frakes and 
Francis 1990). Various factors including reduced 
obliquity of the Earth's rotational axis, 
palaeogeographic configurations of continents and 
ocean currents, higher atmospheric C0 2 levels, and 
increased levels of solar radiation have been 
suggested as possible causes for the apparently 
high palaeotemperatures (Douglas and Williams 
1982; Creber and Chaloner 1985; Barron 1983, 
1984). Palaeomagnetic evidence (Veevers et al. 
1991) indicates that the Early Cretaceous Western 
Australian floras existed in middle latitudes (45°- 
55°) within presumably warmer climates than 
those experienced by the higher palaeolatitude 
Victorian and Antarctic floras (Douglas 1969, 1973; 
Jefferson 1983). However, fossil woods from the 
Birdrong Sandstone show well-defined growth 
rings consistent with a distinctly seasonal climate. 
Analysis of 48 permineralized conifer wood 
samples from the Giralia Anticline, Carnarvon 
Basin (McLoughlin et al. 1994), showed mean 
sensitivity values in the range of 0.148 to 0.673 [i.e. 
complacent to strongly sensitive (Fritts 1976)] with 
an average mean sensitivity of 0.348 (moderately 
sensitive). These growth indices together with the 
presence of sporadic false growth rings within the 
woods suggest a pronounced seasonal climate but 
with substantial inter-seasonal variability in 
environmental parameters. 
The presence of matted Taeniopteris daintreei 
leaves in the Bullsbrook Formation suggests a 
deciduous or semi-deciduous habit for these 
pentoxylaleans consistent with evidence from the 
Victorian Cretaceous (Douglas and Williams 1982; 
Drinnan and Chambers 1986) which suggests that 
