Tertiary megafossil flora of Maslin Bay, South Australia: numerical taxonomic study of selected leaves

Fifteen new species belonging to five genera (one, Mesibovia, newly described) of the Podocarpaceae with imbricate leaves are described from Oligocene-Early Miocene localities in Tasmania. Nine of these species belong to Dacrycarpus, which is now extinct in Australia, and their living affinities are widespread in latitude and altitude from New Zealand to New Guinea. Three species of Dacrydium s. str. demonstrate that this genus was diverse in Tasmania in the Tertiary, although it is now extinct in Australia. A species of Microstrobos, which is very similar to the extant alpinelsubalpine Tasmanian endemic M. niphophilus, occurs in both high-and low-altitude sites, and suggests that this type was once more widespread. The Oligocene Lagarostrobos marginuta is intermediate between the two extant species of Lagarostrobos, and suggests a closer relationship between them than do other lines of evidence. Mesibovia rhomboideu, recovered from three localities, shares features with several extant genera, and is of importance in understanding evolution within this group. The significance of the fossils for climatic and vegetation reconstruction is discussed.

Section: Introductionmentioning

confidence: 95%

Fossil imbricate-leaved Podocarpaceae from tertiary sediments in Tasmania

Wells¹,

Hill²

1989

“…Most extant Proteaceae have this distinctive combination of features, and it is unknown in any other family (Blackburn 1981;Carpenter 1994;Carpenter and Jordan 1997), including the likely sister group of Proteaceae, Platanaceae (Chase et al 1993). Some extant Proteaceae do not have these features (e.g.…”

Section: Fossil Identification Nomenclature and Terminologymentioning

confidence: 99%

The macrofossil record of Proteaceae in Tasmania: a review with new species

Jordan¹,

Carpenter²,

Hill³

1998

About 10 taxa of Proteaceae are known from the Early Eocene in Tasmania, onefrom a Late Eocene site, 22 from four Early Oligocene sites, one from a LateOligocene–Early Miocene site, 12 or 13 from two Early Pleistocene sites,and five or six from the Middle and Late Pleistocene. Most of the Tertiaryfossils are of extinct species, but the extant speciesLomatia fraxinifolia andTelopea truncata as well as apparent close relatives ofthe subalpine rainforest species Orites milliganii, andthe subtropical rainforest species O. excelsa have beenrecorded from the Early Oligocene. None of the Early Oligocene species areknown from more than one site, implying very high regional diversity, andfloristic differentiation among the sites. High diversity of Proteaceae atsome sites may be associated with oligotrophic soils. There is no evidence ofany of the modern species-rich scleromorphic groups of Proteaceae exceptBanksiinae. Scleromorphy was well established in Oriteae, Embothrieae andBanksiinae by the Early Oligocene. The Early Eocene fossils have very smallstomata, sparsely distributed on the leaf, which may have been due to elevatedatmospheric CO2. All extant Tasmanian genera and manyextant species as well as some extinct species were present by the EarlyPleistocene. The specific diversity within the region was probably higher thanit is now. In order to resolve a nomenclatural problem within the genusProteaciphyllum, EuproteaciphyllumG.J.Jord., R.J.Carp & R.S.Hill, gen. nov. is proposed and this name isapplied to 10 previously described species. The Tasmanian fossil taxa includethree new records, and nine new species:Euproteaciphyllum brookerensis G.J.Jord., R.J.Carp.& R.S.Hill, sp. nov., and E. tasmanicum G.J.Jord.,R.J.Carp. & R.S.Hill, sp. nov. from Early Eocene sediments; andOrites milliganoides G.J.Jord., R.J.Carp. & R.S.Hill, sp. nov., O. scleromorpha G.J.Jord., R.J.Carp.& R.S.Hill, sp. nov., E. papillosumG.J.Jord.,R.J.Carp. & R.S.Hill, sp. nov., E. polymorphumG.J.Jord., R.J.Carp. & R.S.Hill, sp. nov.,E. microlobium G.J.Jord., R.J.Carp. & R.S.Hill, sp.nov., E. falcatum G.J.Jord., R.J.Carp. & R.S.Hill,sp. nov., and E. serratum G.J.Jord., R.J.Carp. & R.S.Hill, sp. nov. from Early Oligocene sediments.

“…!y vegetative twigs (Se! !ing 1950; Pike 1953a, 1953b;Townrow 1965;Blackburn 1981;Greenwood 1987;Wells and Hill 19896) but reproductive structures have also been described (Ettingshausen 1886(Ettingshausen , 1888Greenwood 1987. ) The most common podocarpaceous genus in Tertiary sediments in south-eastern Australia is Dacrycarpus (Table l), which is known from several localities in the region (Fig.…”

Section: Introductionmentioning

confidence: 95%

Evolution of Acmopyle and Dacrycarpus (Podocarpaceae) foliage as inferred from macrofossils in south-eastern Australia

Hill¹,

Carpenter²

1991

Macrofossil specimens of Dacrycarpus and Acmopyle from south-eastern Australia are investigated. The specimens previously assigned to D. praecupressinus are revised, with one placed in a different genus and new species, Podocarpus witherdenensis, and some placed in a new species, D. latrobensis. One specimen is retained as the lectotype of D. praecupressinus. Dacrycarpus eocenica is re-examined and it is concluded that this species is not Dacrycarpus, but probably belongs to an extinct podocarpaceous genus. Dacrycarpus setiger is transferred to Acmopyle, and three new Acmopyle species, A. florinii, A. glabra and A. tasmanica, are described. It is hypothesised that during the Tertiary in south-eastern Australia stomatal distribution was reduced on Dacrycarpus and Acmopyle foliage. In Dacrycarpus the bilaterally flattened foliage type (which has a greater photosynthetic area than the bifacially flattened foliage) became rare or extinct after the Early Oligocene, prior to the extinction of the genus in the region. Acmopyle has not been recorded in the region after the Early Oligocene. A trend towards reduction in leaf size at high latitudes has previously been demonstrated in angiosperms but not gymnosperms and, along with the reduction of stomatal distribution, probably represents convergent evolution in response to climatic change.