Records of the Western Australian Museum 18: 19-65 (1996). 
Early Cretaceous macrofloras of Western Australia 
Stephen McLoughlin 
School of Botany, The University of Melbourne, Parkville, Victoria 3052, Australia 
Abstract - Western Australian, Lower Cretaceous, macrofloras from the 
Broome Sandstone and Callawa Formation (Canning Basin), Nanutarra 
Formation and Birdrong Sandstone (Carnarvon Basin), Cronin Sandstone 
(Officer Basin), and Leederville and Bullsbrook Formations (Perth Basin) 
incorporate a range of lycophytes, ferns, pteridosperms, bennettitaleans, and 
conifers. The new monotypic genus Roebuckia is established for spatulate 
fern fronds (R. spatulata) of possible vittariacean alliance. Other newly 
established species include Phyllopteroides westralensis, Elatocladus ginginensis, 
and Carpolithes bullsbrookensis. Although the Western Australian fossil suites 
reveal some specific differences from other Australian late Mesozoic 
assemblages, several shared index taxa and the high proportion of 
bennettitaleans support correlation with the Victorian Neocomian 
Ptilophyllum-Pachypteris auslropapillosa Zone (Zone B). Some Western 
Australian taxa are shared with Indian assemblages but fewer similarities 
exist with other Gondwanan Early Cretaceous floras. The representation of 
several hydrophilous fern, lycophyte, and pteridosperm groups together 
with growth indices from fossil woods implies a seasonal humid 
mesothermal climate for the Western Australian cratonic margin during the 
Neocomian-Barremian. Minor differences between the Western Australian 
assemblages are attributable to local depositional and preservational factors. 
INTRODUCTION 
This paper reviews all Western Australian 
Cretaceous plant fossils held in the collections of 
the Western Australian Museum and the 
Department of Geology and Geophysics of the 
University of Western Australia together with 
limited material held in the Australian Museum, 
Sydney. As all specimens lack preserved organic 
matter, descriptions are based on gross 
morphology, ornamentation, and venation 
patterns. This procedure necessarily places 
limitations on the degree of discrimination between 
some taxa. However, the scarcity of previous 
studies on the Western Australian fossil floras 
invites this systematic appraisal in order to fill 
some major gaps in the knowledge of Australia's 
Cretaceous phytogeography. 
The relative tectonic stability and deep¬ 
weathering associated with much of the central 
and western part of the Australian continent since 
the mid-Mesozoic has removed from outcrops 
most of the organic material required for 
palynological studies. Apart from scarce vertebrate 
trackways (Colbert and Merrilees 1967; Long 1990), 
plant macrofossils are virtually the only fossil 
remains available in outcrop to date and 
palaeoenvironmentally categorize Western 
Australian Cretaceous terrestrial strata. No studies 
dealing with stratigraphic and petroleum 
exploration drilling have reported significant 
assemblages of plant macrofossils from subsurface 
Cretaceous strata in Western Australia. Retallack 
(1977, 1980) and McLoughlin (1993) have 
illustrated differences in palaeosol development 
and the composition of plant fossil assemblages in 
Australian Permian and Triassic strata according 
to variations in local and regional depositional 
settings. Such sedimentological and taphonomic 
controls also apply to the Cretaceous assemblages 
offering an important tool for detailed 
interpretation of non-marine sedimentary facies. 
Additionally, permineralized, mollusc-bored, 
driftwood preserved in Lower Cretaceous marine 
sediments has aided the definition of sequence 
stratigraphic boundaries and systems tracts 
(McLoughlin et al. 1994). Palaeobotanical 
investigations of the diversity of plant groups 
together with anatomical indices such as growth 
ring variation are also useful for the categorization 
of palaeoclimates and the identification of major 
food sources available to the large Cretaceous 
herbivorous dinosaurs. 
PREVIOUS STUDIES 
Douglas (1969, 1973), Drinnan and Chambers 
(1986) and McLoughlin et al. (1995) have provided 
the most detailed studies of Australian Cretaceous 
fossil plants dealing with macrofloras from the 
Gippsland, Otway and Eromanga Basins. Other 
