Early Cretaceous macrofloras 
49 
(Neocomian-?Aptian) and Yarraloola Conglomer¬ 
ate (Neocomian-?Barremian) of the Carnarvon 
Basin, Dandaragan Sandstone (?Barremian- 
?Aptian) and Molecap Greensand (Cenomanian- 
Santonian) of the Perth Basin, and Nakina 
Formation (Barremian-lowermost Aptian) of the 
Collie Basin (Simpson 1912; Cox 1961; Playford et 
at. 1976; Hocking 1990, Buckhouse et at. 1995). 
Description 
Woods typically fragmentary, seldom exceeding 
50 cm long and 15 cm diameter, randomly 
orientated in sediments. Woods show extensive 
biogenic borings (Figures 10E,H). Woods preserved 
by siliceous and phosphatic permineralization, 
strongly weathered and infiltrated by iron-oxide 
and clay minerals. Only secondary xylem tissues 
are preserved. Prominent growth banding evident 
(Figures 10G,H) but details of pitting arrangement 
on individual cell walls often poorly defined or 
absent (Figure 10D). Relatively sparse uniseriate 
xylem rays consist of 1-12 (av. 4) cells (Figure 10F). 
Uniseriate or rarely biseriate bordered pits are 
sparsely evident on radial walls of xylem tracheids. 
Tangential walls not pitted. Pits have oblique slit¬ 
like apertures where discernible. Growth bands 
variable in width (0.06-12 mm) both between and 
within specimens. False growth rings sporadically 
developed in some specimens. In most cases 
middle lamella (initially consisting of pectinoid 
compounds between the primary walls of adjacent 
cells) has been degraded producing a wood texture 
that appears to consist of detached or partially 
detached tracheids. Cambium, phloem, and bark 
tissues absent. Primary xylem and pith poorly 
preserved or masked by iron oxides. 
Comments 
The small pith content of the plants (pycnoxylic 
axes) suggests that the woods derive from the 
dominant arborescent elements of the Australian 
Early Cretaceous vegetation (viz., the podocarp or 
araucarian conifers) rather than fern, pteridosperm, 
or bennettitalean groups that typically contain a 
large proportion of pith within the stem (manoxylic 
axes). Permineralized wood belonging to podocarp 
and araucarian conifers is common in Gondwanan 
Cretaceous sediments (Sahni 1931; Jefferson 1983; 
Francis 1986; Frakes and Francis 1990; Francis and 
Coffin 1992) and the foliage attributable to these 
groups is abundant in coeval Western Australian 
strata. Identification of fossil conifer woods is 
largely based on pitting arrangements on the radial 
walls of longitudinal xylem tracheids and ray cells 
but due to poor preservation such details are not 
available for most Western Australian specimens. 
The absence of typically araucariacean closely 
spaced multiseriate hexagonal bordered pits on 
radial tracheid walls and sporadic presence of 
uniseriate bordered pits with oblique apertures 
suggests that these woods have podocarpacean 
affinities although cupressacean woods also have 
similar pitting arrangements (Greguss 1955). The 
prominent but variable growth banding and 
occasional development of false growth rings 
implies a distinctly seasonal climate but with 
considerable intra- and inter-seasonal variability 
McLoughlin et at. (1994). 
Cox (1961) illustrated infilled molluscan borings 
from the Nanutarra Formation (Early Cretaceous, 
Carnarvon Basin) both with and without traces of 
associated fossil wood. The casts are probably 
remnants of teredinid or pholadid boring casts left 
behind after the degradation of coniferous 
driftwood. One wood specimen in the Birdrong 
Sandstone assemblage shows a cross-section of an 
unidentified bivalve preserved within an 
excavation chamber (Figure 10E). 
Saprophytic fungi 
Figures 11A-I 
1994 Fungi within wood; McLoughlin et at.; p. 455; 
figures 9a-l. 
Material 
UWA120187, UWA120217, UWA120228, 
UWA120229, UWA120231, UWA120232. 
Distribution 
Birdrong Sandstone (Neocomian-?Aptian), 
Carnarvon Basin. 
Description 
Several fossil wood specimens from the Birdrong 
Sandstone, Carnarvon Basin, show zones of partly 
degraded cells or cavities which are circular, 
elliptical, or irregular in transverse section and 
elliptical in longitudinal section. The cavities are 
up to 4 mm in axial length and 0.2-0.9 mm in 
^ Figure 10 A, Winged seed with portions of base and apex removed; WAM P.89.191; Broome Sandstone; x 6; B, Cast 
of ribbed axis; WAM P.63.30; Broome Sandstone; x 1; C, Rhizomopteris sp.; WAM P.89.184; Broome 
Sandstone; x 2; D,F,G, Mesembrioxylon sp.; (D) radial section with three groups of ray cells, UWA120187, x 
60; (F) tangential section showing rays generally comprising 2-4 cells, UWA120199, x 30; (G) transverse 
section showing transition from latewood (bottom) to earlywood (top), UWA120186, x 30; all from 
Birdrong Sandstone; E,H, Transverse sections of Mesembrioxylon wood showing variation in growth rings 
and intensive bivalve borings filled by calcite and/or glauconitic sand. Note preserved bivalve within 
bored cavity (E; arrowed); (E) UWA120220, x 2; (H) UWA120208, x 1.5; both from Birdrong Sandstone. 
