Miocene wood from the coal measures, ,.

DAVID R. GREENWOOD

GREENWOOD, DAVID R., 30.9.2005. Miocene wood from the LaTrobe Valley coal measures, Victoria, Australia. Alcheringa 29, 351-363. ISSN 0311 5518.

An initial study of a collection of fossil conifer wood is reported from the late early Miocene Yallourn Clays, an interseam unit intergrading into the base of the early to middle Miocene Yallourn seam of the LaTrobe Valley, Victoria in southeastern Australia. The fossil wood shares characteristics with the modern genera Dacrycarpus and Dacrydium. On the basis of contiguous, uniseriate tracheid pitting and 1-2 podocarpoid cross field pits, it is placed in the form genus Podocarpoxylon, and the new species P. latrobensis. The wood is compared with extant Podocarpaceae and other Australian fossil woods. Its ring anatomy is consistent with low temperature or rainfall seasonality in the early Miocene.

David R. Greenwood [[email protected]], Sustainability Group, Victoria University, St Albans campus, PO Box 14428, City MC, VIC 8001, Australia; received 18.7.2003; revised 6.1.2005. Current address; Environmental Science, Brandon University, 270-18th Street, Brandon, MB, Canada, R7A 6A9.

Key words: Miocene, wood, Podocarpaceae, coal, LaTrobe Valley, Australia MIOCENE vegetation in Australia is primarily Australia (Taylor et al. 1990), a wood character known from fossil pollen and the macrofossil that is consistent with deciduous forests record of leaves or reproductive organs. Bishop (Greenwood 2001). The paucity of systematic & Bamber (1985), Leisman (1986), and Bamford & analysis of Australian Cenozoic wood is McLoughlin (2000), are the sole recent systematic perplexing given the abundance of material readily accounts of Australian Cenozoic fossil wood, available and the attention given to systematic although early and more recent Australian analysis of modern taxa of Australian forest trees workers noted the presence and quality of (e.g. Dadswell & Eckersley 1935, 1940, Dadswell preservation of Cenozoic fossil wood in the 1972, Ilic 1991, see also Greguss 1955). In their brown coals of the LaTrobe Valley of Victoria account of the Australian fossil record for and in South Australia, and in other sediments in conifers, Hill & Scriven (1998) did not cite any these States and also in New South Wales, fossil wood taxa. including silicified wood (Chapman 1918, Nobes The brown coal deposits of the LaTrobe 1922, Howchin 1923, Chapman 1926, Barnard 1927, Valley of South in Victoria (38° 05’S, Patton 1928, 1958; Gill 1952, Douglas 1983, Taylor 146° 05’E; Fig. 1) have been palaeobotanically et al. 1990). Sahni (1920) described two investigated since early last century (Chapman angiosperm species from Paleogene sediments 1925a, 1925b; Deane 1925, Greenwood et al. 2000, near Brisbane in Queensland, and Rozefelds & Holdgate 2003). They were also the subject of Baar (1991) have described termite frass in numerous investigations by Cookson and her co- Cenozoic wood from Queensland. Fossil wood workers (Cookson 1947, 1950, 1953; Cookson & with well-defined uniform growth rings has been Duigan 1950, 1951; Cookson & Pike 1953a, 1953b; reported from high palaeolatitudes sites in Pike 1953), and others (e.g. Willis & Gill 1965), Paleocene floras from the Southern Highlands of culminating in Duigan’s (1965) description of the 0311/5518/2005/02351-13 $3.00 © AAP Miocene palaeovegetation. Numerous palyno- 352 DAVID R. GREENWOOD ALCHERINGA

Fig. 1. Location map showing site of the Open Cut brown coal mine and the Latrobe Valley, and other localities where Cenozoic fossil wood has been described from southeastern Australia (1 Moorlands, 2 Lachlan River, 3 Monaro Plains / Southern Highlands, 4 Yallourn mine, 5 Morwell mine, 6 Jungle Creek). Inset A, sketch map showing Early Miocene palaeolatitude of the study area, modified from a map provided by S.J. Gallagher. Inset B, detail of the LaTrobe Valley showing fossil collection site (5). logical studies (Luly et al. 1980, Sluiter & Kershaw al. 1995, Kershaw 1996), and the macrofossil work 1982, 1996; Kershaw et al. 1991, 1994; Sluiter et of Blackburn (1980, 1985) and Blackburn & Sluiter ALCHERINGA MIOCENE WOOD FROM VICTORIA 353

Fig. 2. Annotated lithological log of site of fossil wood collection (April, 1981) from a vertical exposure of the Yallourn Clays in the Morwell Open Cut Mine. Bulk samples macerated from the 1-5 m interval yielded leafy shoots of Dacrycarpus latrobensis and other Podocarpaceae. Fossil wood samples were collected at ‘A’ from one in situ log. (1994) provided insight into the palaeoecology noted above, surprisingly little has been of the middle Miocene Yallourn Coal seam and published on the fossil wood from the LaTrobe the early Miocene Morwell coal vegetation. As Valley brown coals and associated sediments 354 DAVID R. GREENWOOD ALCHERINGA

(e.g. Patton 1958), and the palaeobotany of the 1994; Greenwood et al. 2000, Greenwood & interseam sediments in general, despite an Christophel 2005). apparent abundance of material (Greenwood et The topmost fine silty clays were al. 2000). This report is an initial attempt to redress progressively more carbonaceous upsection and this situation. graded into a thin exposure of the overlying Yallourn Coal seam. Blackburn & Sluiter (1994) considered the Yallourn Clays intergradational Geological setting with the Yallourn Coal seam. Palynological The LaTrobe Valley of southeastern Australia is analysis of samples from the upper 2 m of the a major area of brown coal extraction (Hocking section containing the fossil wood yielded 10.8- 1972, Holdgate & Clarke 2000, Holdgate 2003). 33.0% Nothofagidites (6.3-20.8% subgen. Three open cut mines in the vicinity of the towns Brassospora & 0.5-12.5% subgen. Lophozonia), of Morwell and Traralgon (Fig. 1) provide access 7.0-23.5% Myrtaceae (incl. 0-0.3% Eucalyptus to extensive lateral and vertical stratigraphic simplex & 4.5-17.0% Syzygium complex), 0-3.5% sequences of both the brown coal seams and the Proteaceae, and 10-32.5% conifer pollen (incl. 7.0- inter- and intraseam clays, sands and gravels. 28.8% Podocarpaceae) (I.R.K. Sluiter, pers. comm. Major interseam clastic sediments are laterally 1981 in Greenwood 1981; see also Blackburn & extensive, and generally extend across the whole Sluiter 1994). This assemblage is typical for early basin (Holdgate 2003, Holdgate et al. 1995). The Miocene sediments in southeastern Australia, and Yallourn Clays constitute an interseam clastic unit is indicative of a mixed Nothofagus-Syzygium- between the Morwell 1A Coal Seam (M1A), and conifer closed forest, although sclerophyllous the Yallourn Coal Seam. According to Luly et al. forest may also have been present based on the (1980), the Yallourn Clays are basal to the low counts of Eucalyptus simplex pollen. Triporopollenites bellus Zone of Stover and Occasional large pieces of conifer wood were Partridge (1973), and are thus middle Miocene. encountered in the topmost unit, including in However, more recent stratigraphic analyses situ stumps with associated Dacrycarpus place the Yallourn Clays (Interseam Influence latrobensis leafy shoots (Blackburn & Sluiter Zone 12 [IIZ 12]) as spanning the boundary of 1994). One sample of this wood is dealt with the Upper Proteacidites tuberculatus and systematically here. Triporopollenites bellus Zones, and thus late early Miocene (Holdgate & Sluiter 1991, Blackburn & Sluiter 1994, Holdgate et al. 1995, Materials and methods Holdgate 2003; Holdgate & Gallagher 2003). Histology of the fossil material was analysed The fossil material described herein was using standard histological sectioning collected by the author and David T. Blackburn techniques with wood pretreated in 80% ethanol in April 1981 from an exposure of the Yallourn prior to sectioning. Transverse, radial and Clays in the north-west corner of the Morwell tangential sections were made using a sledge Open Cut Coal Mine operated by the then State microtome and the sections placed in an alcohol Electricity Commission of Victoria (see also dehydration series (80%, 90% and 100% ethanol), Blackburn & Sluiter 1994, p. 350). A 10 m vertical remaining in each bath for at least 5 minutes. The sequence overlying the Morwell 1A seam was dehydrated sections were immersed in xylene for sampled through basal coarse white sands 5-10 minutes and mounted in xam neutral interbedded with carbonaceous seams, mounting medium on glass microscope slides, gradually replaced by very fine silty clays barren and photographed using black and white film at of leaf fossils (Fig. 2). Analysis of macrofossils 50 ASA in the former Botany Department, extracted from the lower 5 m of this sequence University of Adelaide. Terminology of wood (Fig. 2) is reported elsewhere (Greenwood 1981, histology follows Greguss (1955), but using the ALCHERINGA MIOCENE WOOD FROM VICTORIA 355

pit descriptions and types from Philippe (1995). Data on modern wood anatomy are principally based on Greguss (1955), but using the systematic treatment of the Podocarpaceae from Page (1988). The fossil wood xylotomy slides are lodged in the University of Adelaide Palaeobotany Collection, Department of Environmental Biology. The original fossil wood specimens were destroyed in a fire at the University of Adelaide’s Thebarton campus facility in 1998.

Systematic palaeobotany

Phylum CONIFEROPHYTA Order CONIFERALES Family PODOCARPACEAE

Podocarpoxylon Gothan, 1908 Type species. Podocarpoxylon juniperoides Gothan, 1908.

Podocarpoxylon latrobensis sp. nov. (Figs 3 - 5) Holotype. Xylotomy slides; YC-wood 001. Type locality. Yallourn Clays, late Early Miocene, Morwell Open Cut coal mine, Victoria. Etymology. Named for the LaTrobe Group sediments and the LaTrobe Valley from which it was collected. Diagnosis. Wood with simple tracheids with circular pits. Growth rings indistinct, tracheids squarish in transverse view, and parenchyma rare. Rays 1-2 cells high in tangential view, and lacking pits. Pits in 1-2 rows on tracheids in radial view; ray cells with smooth horizontal and tangential walls. Cross field with one

Figs 3-5. Histological sections of fossil Podocarpaceae wood. Fig. 3, transverse section showing indistinct growth rings and general appearance of tracheids in transverse section; scale bar = 100 µm. Fig. 4, radial longitudinal section showing tracheids in long section with prominent podocarpoid pits; scale bar = 25 µm. Fig. 5, detail of cross-field pits showing ray cells (L to R across vertically oriented tracheids); scale bar = 25 µm. Inset in Fig. 5, sketch of cross field podocarpoid pit, traced from pit in central view. 356 DAVID R. GREENWOOD ALCHERINGA

podocarpoid pit, or rarely none or 2 pits. resin ducts indicates that the fossil wood represents the extant family Podocarpaceae Description. Transverse section: growth rings (Greguss 1955; Table 1). Podocarpoxylon generally indistinct, the transition from early to latrobensis shares a number of characteristics late wood poorly defined; tracheids 25-75 x 40- with extant taxa in the Podocarpaceae (Table 2). 75 µm (40 cells); rays 3-10, rarely 1-14 tracheids The tracheids are squarish in transverse section apart; horizontal walls generally unpitted; in P. latrobensis (Fig. 3) and a majority of the parenchyma cells rare to absent; tracheids square extant taxa surveyed, including both species of to rarely rectangular in cross section. Tangential Dacrycarpus and Dacrydium cupressinum longitudinal section: rays 2-18 cells high but Solander ex G. Forst., but may also be roundish in typically 5-12 cells high and invariably Dacrydium elatum (Roxb.) Wallich ex Hook., uniseriate; tracheid walls smooth, tangential Podocarpus elatus R.Br. ex Endl. and walls typically smooth and unpitted; the walls Prumnopitys ferruginoides (RH Compton) de of some tracheids irregular through the presence Laubenfels. Wood parenchyma in transverse of crassulae; ray cells in cross section from section was rare in the fossil and in Microcachrys square-circular to circular, with marginal cells tetragona (Hook.) Hook.f., and was absent in slightly tapered to rarely triangular and their walls Phyllocladus trichomanoides D. Don, but was usually thin, pitting not seen; height commonly common in all of the other species surveyed. 12-17 µm, width 12-15 µm (20 pits). Radial Medullary rays in tangential section were longitudinal section: pits common to scarce on uniseriate in Podocarpoxylon latrobensis, and radial walls of tracheids, occurring singly or in a in the majority of extant species surveyed (rarely single row, sometimes staggered, rarely in two biseriate in Dacrycarpus). Rays varied in height rows, 15 µm in diameter (15 pits), rarely significantly between the extant taxa, but were of occupying the full width of the tracheid, generally a similar number of cells high in both P. circular though flattened when crowded, never latrobensis (2-18 cells), Dacrycarpus imbricatus touching, and usually in groups of 2 to 4; (Blume) de Laub. (1-15 cells), both Dacrydium apertures of pits ellipsoid to eye-shaped, rarely species, (1-10 cells), Retrophyllum minor circular, 4-7 µm in length, generally or nearly so (Carrière) Page and Phyllocladus trichomanoides oblique, forming an X-shape with aperture of (1-12 cells). The size ranges of ray cells in adjacent pit; cross field commonly with one tangential section overlaps in many of the species, podocarpoid pit, occasionally none, rarely two; but on average Podocarpoxylon latrobensis has pit aperture eye-shaped, almost touching sides similar size ray cells to Dacrycarpus dacrydioides but within a wide circular border 10-15 µm in (A. Rich.) de Laub., the two Dacrydium species, diameter, aperture oblique to rarely vertical, 9-14 Phyllocladus trichomanioides, Microcachrys µm in length; marginal cells of rays indistinct tetragona, and Podocarpus elatus (Table 2). In from other ray cells, thin walled; some tracheids common with only Dacrycarpus dacrydioides, with crassulae; rays homogeneous and lacking Podocarpoxylon latrobensis lacks pits on the transverse tracheids. tangential walls of the tracheids. In radial section, Comparison with modern and fossil P. latrobensis and the following extant taxa have wood 1-2 pit rows on the tracheids; both species of Dacrycarpus, Dacrydium elatum, Retrophyllum The absence of vessels and the predominance of minor, and Prumnopitys ferruginoides. The pits simple tracheids with circular pits indicates that on the tracheids were of similar diameter in all the fossil wood is coniferous. The presence of species. In the cross field, Podocarpoxylon podocarpoid pits (or ‘Podocarpoïde’, of Philippe latrobensis had a similar number of pits to 1995) and homogeneous uniseriate rays, angular Dacrycarpus dacrydioides and D. imbricatus. tracheids in cross section, and the absence of However, the pits in the cross field were of greater ALCHERINGA MIOCENE WOOD FROM VICTORIA 357 Cross field pit type Dacrydioid usually Dacrydioid usually Cupressoid rarely Dacrydioid Dacrydioid Number of pits on ray cells Number of pits on tracheids Bordered pits on tangential tracheid walls Ray width in cells Ray height in cells rings distinct Growth + yes 1-6 1 + 1-6 Podocarpoid + yes 1-2 1-2 + yes & no 1-16 (22) 1 X 1-2 (0) 1-4 Podocarpoid or + Some species 1-40 (60) 1 X 1-2 0-4 Either Podocarpoid or . Wood structure (main characters only) contrasting the major genera (as per Wood . Wood parenchyma Table 1 Table Australian conifer Greguss 1955; systematics from Page 1988) of the principal families. X present rarely or occasionally; + always present; - absent. Transverse surface Tangential surface Radial surface Square - yes 1-22 1-2 X 1 1 (2) " 1-2 Square X 1-22 1 1 yes Square - X yes 1-6 (12) 1-2 + 1-2 1 (2-3) Rarely Podocarpoid, rounded rounded Rounded Rounded X X no 1-10 (40) no 1 (2) 1-16 (20) 1 (2) + X 1-5 1-4 1-16 Araucarioid 1-12 Araucarioid Rounded + Some species 1-36 1 (2) X 1-2 1-3 Rarely Podocarpoid, Rounded + no 1-8 (10) 1-2 X 1-2 2-3 Usually Podocarpoid, 1-2 X Usually (10) 1-2 2-3 1-8 Rounded + no rarely rounded Usually square, Tracheid shape s.l. Square to s.l. Angular to Families and genera Podocarpaceae: Acmopyle Araucariaceae: Agathis Araucaria Dacrydium Podocarpus Microcachrys Phyllocladus Cupressaceae: Callitris Prumnopitys

358 DAVID R. GREENWOOD ALCHERINGA Pit diam. (µm) (µm) diam. Pit 3-8 7-8 4-12 3-10 7-14

10-15 10-12 10-12

(20-22)

Number of pits pits of Number 3) 3) 4) (2) (3) (6) (5) (2)

walls smooth smooth walls

Tangential Tangential

walls smooth smooth walls

Horizontal Horizontal

parenchyma smooth smooth parenchyma

Horizontal walls of wood wood of walls Horizontal

No. of pit rows rows pit of No.

Pit diam. (µm) (µm) diam. Pit

Tracheids Ray cells Cross field Cross cells Tracheids Ray

parenchyma smooth smooth parenchyma

Horizontal walls of wood wood of walls Horizontal Pit diam. (µm) (µm) diam. Pit

of tracheids pits pits

Tangential walls

Width (µm) (µm) Width

Height (µm) (µm) Height

Width in cells cells in Width

Height in cells cells in Height

indistinct indistinct

distinct distinct

Wood parenchyma parenchyma Wood

Transverse surface rounded Tangential surface Radial surface squarish squarish (2- 1 + + + 1 8-13 8-13 ? x 1-3 5-13 + + + 2 8-20 x 12-18 10 ? 1 10-35 1-3(7) 15-40 x - + - + 1 1-2(6) + - - + Tracheids Growth rings Rays Ray cells x + + - + 1-10 1 12-18 8-10 x 11-12 + 16-17 1-2 + + + 0-2 10-11 0-2 + 1-2 16-17 + 11-12 x 8-10 12-18 1 1-10 x + - + 0-1 + 9-14 1-2 (2) x 16-22 7-8 8-9 + x 1 11-12 8-10 + + + 16-18 18-22 + + + 1 - 1 + 11-13 1-6 + x 1-9 + 1 - + + - x - + 2-18 1 12-17 12-15 - - x 10-15 1(2) x + + 0-1 + + x 1(2) - - 12-15 10-15 x 12-17 1 2-18 + - x + + x + + - 1-6 1 20-28 10-12 + 11-12 x 13-14 1 + + + 1 (2) 8-11 (2) 1 1 + 13-14 x 11-12 6-7 + 0-2 10-12 1-2 + + + + 1-2 + + - 9-10 1(2) - 20-28 14-16 + 1 15-17 12-14 1-6 + x + - + 8-10 x 1(2) 11-12 1-60 + x 8-12 1-2 1-15 + - 10-13 + 1 1 + + 16-18 + 14-15 x 10-16 14-16 2-3 + 10-14 1-2 1 1-10 13-14 (2) + x - + + 13-14 + 12-16 16-20 1 18-20 (2) + + + 1 1 ? 7-9 1-20 + ? - 14-18 + - + 10-14 1 (3- 1 1 + 1-8 + - x 18-20 7-8 7-11 + 1 14-18 17-20 1 + 1 1-2 + 1-8 + - 7-8 12-14 + 6-8 - + x + 1 ? 14-17 13-18 8-10 ? + 1 7-8 1-80 + - x + - 12-16 1 1-12 + - - + + + x - x 1-12 1(2) 12-33 10-30 x 10-12 ? 12-18 1 + + + 1 (2- 1 1 + 12-18 ? 10-12 x 10-30 12-33 1(2) 1-12 + x - x 8-20 (2) 1 + + ? 1(2) 12-18 ? 10-13 + 5-15 8-28 1 1-3(7) + - - + F

F F F F Species Acmopyle pancheri Dacrycarpus dacrydioides D. imbricatus Podocarpoxylon latrobensis P. australe P. minor P. yallournensis Dacrydium cupressinum D. elatum Retrophyllum minor Falcatifolium taxoides Lagarostrobos franklinii Microcachrys tetragona Phyllocladus trichomanoides Phyllocladoxylon annulatus Podocarpus elatus Prumnopitys ferruginoides ALCHERINGA MIOCENE WOOD FROM VICTORIA 359

diameter for P. latrobensis than recorded for these Phyllocladoxylon (Table 2). Krausel (1949) two extant species of Dacrycarpus, but were of synonymised some of Nobe’s (1922) fossil wood similar diameter to those observed in Dacrydium taxa, including Mesembrioxylon sp. ‘Yallourn A’ cupressinum, D. elatum and Falcatifolium in Podocarpoxylon australe. However, Patton taxoides (Brongniart et Grisebach) de Laubenfels (1958) argued that Krausel’s treatment was in (Table 2). error. The primary wood characters for the fossil The most likely extant genus for this material species are shown in Table 2. Comparisons here is Dacrycarpus, on the basis that the specimen will be based primarily on Patton (1958). keys out to Podocarpus dacrydioides (syn. Podocarpoxylon latrobensis shares a Dacrycarpus dacrydioides) in Greguss (1955), number of features with Patton’s (1958) fossil and based on tabulating the principal wood taxa, but is distinct from all these species and so characters (Table 2), the wood anatomy of is recognised as a separate species (Table 2). Podocarpoxylon latrobensis most closely The tracheids are squarish in transverse section matches that of Dacrycarpus imbricatus. in both P. latrobensis and P. australe, but may However, it is difficult in many instances to place also be roundish in the latter species, and are Podocarpaceae wood into a modern genus (e.g. rounded in each of P. minor and P. yallournensis. Table 2). As this specimen lacks any definitive Wood parenchyma is rare in P. latrobensis, P. generic characters, and shares almost as many australe and P. minor, but is common in similarities with Dacrydium as it does with transverse section in P. yallournensis. All four Dacrycarpus, the material is referred to Podocarpoxylon species have indistinct growth Podocarpoxylon. Patton (1958) considered rings (Table 2). Medullary rays in tangential Podocarpoxylon to represent Podocarpus s.l., section are generally uniseriate (rarely biseriate so including such segregate genera as in P. australe) in all four species, and are a similar Dacrycarpus and Retrophyllum. The co- number of cells high in both P. latrobensis (2-18 occurrence with this wood in the sediments with cells) and P. australe (1-12 cells). Rays are much abundant leafy shoots of Dacrycarpus shorter in the other two species (1-7 cells high). latrobensis suggests that this wood represents The size ranges of ray cells overlaps in all four the trunk of the Dacrycapus latrobensis plant. species, but on average Podocarpoxylon However, other podocarpaceous genera are latrobensis has smaller ray cells than the other known from the same sediments (e.g. Dacrydium; species. In contrast to all three previously Blackburn & Sluiter 1994), and also in the absence described Australian Podocarpoxylon species of attached woody stems and leafy shoots, this (Patton 1958), P. latrobensis lacks pits on the proposition must remain speculative. tangential walls of the tracheids, a pattern seen Conifer wood is notoriously nondescript, so also in the extant Dacrycarpus species (Table placement below familial status is often not 2). In radial section, P. latrobensis and P. possible. Nobes (1922) described species of yallournensis have 1-2 pit rows on the tracheids, Mesembrioxylon, Cupressinoxylon (Cupress- whereas P. australe and P. minor have one pit aceae, gen. indet.) and Dadoxylon (Araucari- row. The pits on tracheids in radial section were aceae, gen. indet.) from Moorlands in South of similar diameter in all four Podocarpoxylon Australia and from Yallourn in the LaTrobe Valley. species. However, cross field pits were generally Patton (1958) described five species of fossil of greater diameter for P. latrobensis (10-15 µm) conifer wood from coal deposits in Victoria, than for P. australe (4-12 µm), P. minor (3-8 µm), including four species of Podocarpaceae as three or P. yallournensis (3-10 µm). species of Podocarpoxylon and one species of Palaeoecological implications of Table 2. Wood structure of selected extant and fossil Podocarpaceae (data from Nobes 1922, Greguss 1955, the wood Patton 1958). Key: + = present; - = absent; x = occasional to rare; ? = no data; F = fossil species. A number of wood characteristics are climatically Measurements are ranges (extremes). indicative (Woodcock & Ignas 1994, Greenwood 360 DAVID R. GREENWOOD ALCHERINGA

2001). Annual growth rings indicate seasonality Miocene brown coals are relatively common in of temperature or precipitation; annual variation southeastern Australia, with significant economic of ring widths (or the size of xylem cells within and sub-economic reserves in Victoria and rings, i.e. wood density) is correlated with southern South Australia (Holdgate & Clarke precipitation; and the degree of transition to late 2000). The coal-forming vegetation reflected in wood displayed at the termination of seasonal these coals appears to have been dominated growth is correlated with the rapidity and severity throughout the Cenozoic by conifers and key- of the transition to unfavourable conditions. The taxa of woody angiosperms, such as Banksieae prevalence of homocellular and storied rays varies and other Proteaceae, based on dispersed cuticle with temperature. analysis (Rowett 1991, 1992; Blackburn & Sluiter Patton (1958) noted that Podocarpoxylon 1994, Greenwood et al. 2000, Greenwood & australe, P. minor and P. yallournensis all lacked Christophel 2005). Macrofossil analysis of the distinct growth rings, whereas Phyllocladoxylon Yallourn Coal seam has demonstrated a high annulatus had distinct growth rings. The diversity of both conifers and woody Paleocene fossil wood reported by Taylor et al. angiosperms, based on leaf and fruit remains, and (1990) from the Monaro Plains had well-defined also pollen (Blackburn & Sluiter 1994). uniform growth rings. Of the temperate species Macroscopic remains of Podocarpaceae, chiefly shown in Table 2, Dacrycarpus dacrydioides, leaves and leafy shoots, are relatively common Lagarostrobos franklinii, Microcachrys from the interseam sediments, as well as from tetragona and Phyllocladus trichomanioides other southeastern Australian Cenozoic possess distinct growth rings consistent with a mudstone macrofloras (Cookson & Pike 1953a, winter cessation of growth. The majority of the 1953b; Greenwood 1981, 1987, 1994; Rowett 1991, tropical to subtropical species, i.e. Dacrycarpus 1992; Blackburn & Sluiter, 1994, Hill & Scriven imbricatus, Dacrydium elatum, Falcatifoilum taxoides and Podocarpus elatus, lack distinct 1998, Greenwood et al. 2000, Greenwood & growth rings (Table 2), consistent with growth Christophel 2005). That much of the wood in a low seasonality environment (either preserved in the Morwell and Yallourn Coal seams temperature or rainfall). Both species of was coniferous, and that Podocarpaceae were Dacrydium for which data were available (Table prominent, is well established in the literature 2) lacked distinct growth rings, including the (Patton 1958) and is consistent with other temperate species, D. cupressinum, although the evidence for the presence of Podocarpaceae in latter species occurs in the warmest areas of New the palaeovegetation (Duigan 1965, Luly et al. Zealand. The lack of rings in the two extant 1981, Blackburn & Sluiter 1994). However, only Dacrydium species may therefore suggest a Nobes (1922) and Patton (1958) have dealt with genetic predisposition to indistinct rings in the fossil wood from the coals systematically. This genus. However, the temperate species of present paper then serves to demonstrate that Dacrycarpus had distinct rings, whereas the Podocarpaceae trees were also elements of the tropical species, D. imbricatus, lacked distinct vegetation growing around the lakes and other rings, suggesting an environmental sensitivity water bodies that formed the interseam mudstone to temperature seasonality in Dacrycarpus. The sediments found in association with the LaTrobe lack of distinct growth rings in the wood Valley Coals. The lack of distinct growth rings in described here from the Yallourn Clays matches all described conifer species from the coal and the observations made by Patton (1958), and interseam floras (e.g. Patton 1958; this work) suggests low seasonality of both temperature indicates that the local vegetation did not and rainfall, and strongly indicates a lack of experience seasonal interruptions to growth. The significant frost. fossil wood is therefore consistent with other evidence (e.g. Kershaw 1996) for the lack of Conclusions seasonal extremes in temperature (i.e. no ALCHERINGA MIOCENE WOOD FROM VICTORIA 361

sustained cold period) and the absence of marked Cretaceous to Recent, R.S. HILL, ed., Cambridge seasonality of rainfall in the late Early Miocene University Press, Cambridge. BISHOP, P. & BAMBER, R.K., 1985. Silicified wood of Early of south-eastern Australia. Miocene Nothofagus, Acacia and Myrtaceae (aff. Eucalyptus B) from the Upper Lachlan Valley, New Acknowledgements South Wales. Alcheringa 9, 221-228. CHAPMAN, F., 1918. On the age of the gravels; with a note on the included fossil wood. Proceedings The collection and original analysis of the fossil of the Royal Society of Victoria 31, 166-174. wood was made while based (1981) in the former CHAPMAN, F., 1925a. Notes on the Brown Coal from Botany Department, University of Adelaide, and Morwell, South Gippsland. Records of the Geological was funded under a State Electricity Commission Survey of Victoria 4, 485-487. CHAPMAN, F., 1925b. On some Seed-like bodies from the of Victoria research grant to D.T. Blackburn and Morwell Brown Coal. Records of the Geological D.C. Christophel. I would like to acknowledge Survey of Victoria 4, 487-489. the support afforded to me by the Botany COOKSON, I.C., 1947. On fossil leaves (Oleaceae) and a Department, and by my parents John W. new type of fossil pollen grain from Australian brown  coal deposits. Proceedings of the Linnean Society of Greenwood ( 1988) and C. Roxley Greenwood New South Wales 72, 183-197. during this research. Completion of the COOKSON, I.C., 1953. On Macrozamia hopeites - an early manuscript was facilitated by an ARC research Tertiary cycad from Australia. Phytomorphology 3 grant (A39802019) and the provision of facilities 3( ), 306-312. COOKSON, I.C. & DUIGAN, S.L., 1950. Fossil Banksieae by the Department of Geological Sciences at the from Yallourn, Victoria, with notes on the University of Saskatchewan (Canada) during my morphology and anatomy of living species. sabbatical there in 2001. I also thank Guy Australian Journal of Scientific Research, series B, Holdgate and Stephen Gallagher for advice on Biological Sciences 3(2), 133-165. COOKSON, I.C. & PIKE, K.M., 1953a. The Tertiary LaTrobe Valley coal stratigraphy, and for occurrence and distribution of Podocarpus (section assistance with the illustrations. The work greatly Dacrycarpus) in Australia and Tasmania. Australian benefited from the reviews by Marion Bamford Journal of Botany 1, 71-82. and Mike Pole. COOKSON, I.C. & PIKE, K.M., 1953b. A contribution to the Tertiary occurrence of the genus Dacrydium in the Australian region. Australian Journal of Botany 1, References 474-484. ABELE, C., GLOE, C.S., HOCKING, J.B., HOLDGATE, G., KENLEY, DADSWELL, H.E., 1972. The anatomy of eucalypt woods. P.R., LAWRENCE, C.R., RIPPER, D. & THRELFALL, W.F., Forestry Products Laboratory, Division of Applied 1976. In The Geology of Victoria, 251-350. Chemistry, Technical Paper No. 66, CSIRO, Australia. Geological Society of Australia Special Publication DADSWELL, H.E. & ECKERSLEY, A.M., 1935. The identification 5, J.G. DOUGLAS & J.A. FERGUSON, eds. of the principal commercial timbers other than BAMFORD, M. & MCLOUGHLIN, S., 2000. Cainozoic Eucalyptus. CSIR Bulletin 90, 1-103. euphorbiacean wood from the Canning Basin, DEANE, H., 1925. Fossil leaves from the Open Cut, State . Alcheringa 24, 243-256. Brown Coal Mine, Morwell. Records of the BARNARD, C., 1927. A note on a fossil dicotyledonous Geological Survey of Victoria 4, 492-498. fossil wood from Ulladulla, New South Wales. DOUGLAS, J.G., 1983. What Fossil Plant is That? A guide Proceedings of the Linnean Society of New South to the ancient floras of Victoria. Field Naturalists Wales 52, 113-121. Club of Victoria, Melbourne, 86 pp. BLACKBURN, D.T., 1980. Floristic control on lithotype DUIGAN, S.L., 1965. The nature and relationships of the banding within the Yallourn Seam, Yallourn Open Tertiary brown coal flora of the Yallourn area in Cut; evidence from macrofossil assemblages. S.E.C. Victoria, Australia. Palaeobotanist 14, 191-201. Victoria, Palaeobotany Project, Major Report 2 GOTHAN, W., 1908. Die Fossilien Hölzer von Seymour- (unpublished). und Snow Hill-Insel. Wissenschaftliche Ergebnisse der BLACKBURN, D.T., 1985. Palaeobotany of the Yallourn Schwedischen Südpolar Expedition 1901-1903 3, and Morwell Coal Seams. S.E.C. Victoria, 1033. Palaeobotanical Project, Report 3 (unpublished), 121 GREENWOOD, D.R., 1981. The Miocene fossil flora of the pp, 53 plates. Yallourn Clays and its relationship to the associated BLACKBURN, D.T. & SLUITER, I.R.K., 1994. The Oligo- Morwell and Yallourn Coal floras. Unpublished thesis, Miocene coal floras of southeastern Australia, 328 - Botany Department, University of Adelaide, 98 pp. 367. In History of the Australian Vegetation. GREENWOOD, D.R., 1987. Early Tertiary Podocarpaceae: 362 DAVID R. GREENWOOD ALCHERINGA

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