OFR 151.pdf - CRC LEME

3. TIME SLICE T-3
Age Range: Middle to Late Eocene [49-33.7 Ma]
Zones: Lower to Middle Nothofagidites asperus Zones
Rhombodinium waipawaense to Gippslandica extensa (Corrudinium
incompositum) Zones
3.1 Macrofloras
Macrofossils vary from perfectly preserved organic specimens to silcrete casts. Many taxa
can be assigned to extant families or genera although almost all specimens represent extinct
species within these higher order taxa.
As additional material is described, it is probable some fossil gymnosperms assigned to extant
taxa will be reassigned to form genera, e.g. Hill and Pole (1992). In other instances the
macrofossils confirm that living species are of considerable antiquity. Examples are: (1) the
extant Tasmanian species Phyllocladus aspleniifolius (Podocarpaceae) and Cenarrhenes
nitida (Proteaceae), whose fossil remains occur in a Middle-Late Eocene macroflora at
Hasties, northeastern Tasmania (Pole 1992); (2) the South American Lophosoria
quadrapinnata, a ground fern, whose fossil remains are found in an Oligo-Miocene deposit at
Balfour on the north-west coast of Tasmania (R.S. Hill pers. comm.). The last species almost
certainly migrated into Tasmania during the Eocene-Oligocene transition. Other trends that
become apparent (or more sharply defined) in the macrofossil record during the Middle-Late
Eocene are:
a. An increase in the lapse rate. For example, Christophel and Greenwood (1989)
conclude that ‘foliar physiognomic signatures’ indicate that warm temperate to tropical
rainforest communities growing at lower latitudes in New South Wales were replaced by cool
temperate rainforest types at higher latitudes and elevations in Victoria and Tasmania.
b. An increase in the number of taxa with scleromorphic features. Hill and Merrifield
(1993) and Hill (1998a, 1998b) have proposed that the Australian sclerophyll flora evolved
during the Eocene primarily in response to low soil nutrient levels, especially of phosphorus,
and were pre-adapted to xeric conditions developing during the Late Palaeogene and
Neogene.
Recent publications dealing with fossil macro- and microfossil records (of individual taxa are:
Alangiaceae (Martin et al. 1997), Aquifoliaceae (Martin 1977), Araucariaceae (Bigwood and
Hill 1985, Hill and Bigwood 1987, Hill 1990b, 1995), Casuarinaceae (Christophel 1980,
Scriven and Christophel 1990, Scriven and Hill 1995), Convolvulaceae (Martin 2000),
Cunoniaceae (Barnes and Hill 1999a, 1999b, Barnes and Jordan 2000), Cupressaceae (Hill
and Carpenter 1989, Hill 1995, Hill and Whang 1996), cycads (Hill 1978, 1980, Carpenter
1991a), Droseraceae (Truswell and Marchant 1986), Ebenaceae (Christophel and Basinger
1982), Elaeocarpaceae (Rozefelds and Christophel 1996), Euphorbiaceae (Martin 1974),
Ginkgoaceae (Hill and Carpenter 1999), Isoetaceae (Hill 1988d), Lactoridaceae (Macphail et
al. 1999), Menispermaceae (Hill 1989b), Myrtaceae (Lange 1978b, Christophel and Lys
1986), Nothofagaceae (Christophel 1985, Hill 1983a, 1983b, 1984, 1987, 1988a, 1988b,
1992a, 1994a, 1994b, Scriven et al. 1995, Scriven and Hill, 1996, Swenson et al. 2000),
Podocarpaceae (Greenwood 1987, Hill 1989a, 1995, Wells and Hill 1989, Hill and Carpenter
1991, Hill and Pole 1992, Hill and Whang 1996, 2000, Hill and Scriven 1999), Proteaceae
(Christophel 1984, Carpenter and Hill 1988, Hill 1988c, 1990c, Hill and Christophel 1988,
Rozefelds 1992, 1995), Psilotaceae (Carpenter, 1988), Schizaeaceae (Rozefelds et al. 1992),
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