The Early Late Miocene Floras–First Evidence of Cool Temperate and Herbaceous Taxa more

Chapter 6 The Early Late Miocene Floras – First Evidence of Cool Temperate and Herbaceous Taxa Abstract A remarkable change is noticed in the 10 Ma floras of Iceland. In contrast to older floras, herbaceous elements become prominent in the palynological record, and, for the first time, small-leaved Ericaceae are encountered in the macrofossil record. The high number of pollen taxa recovered from sedimentary rock samples of the Tröllatunga-Gautshamar Formation account for the remarkable richness of this flora (ca 100 taxa). Pollen, spores, and macrofossils are all exquisitely preserved. Importantly, many taxa that were characteristic of the older Brjánslækur-Seljá Formation, 12 Ma, have not been recorded from any locality belonging to the 10 Ma and younger formations. Examples for such taxa are: Glyptostrobus, Cryptomeria, Sequoia (Cuppressaceae s. l.), and among the angiosperms Comptonia, Liriodendron, Magnolia, and Sassafras. At the same time, a number of warmth-loving taxa occur for the first time in the 10 Ma formation. Most spectacular among the new elements are Ginkgo and the extinct Fagaceae Trigonobalanopsis, both of which are documented by their pollen. Pseudotsuga and Decodon are other taxa that appear for the first time in Iceland. In this chapter, the taxonomic composition of the 10 Ma floras of Iceland has been investigated. In addition, floristic turnovers between 12 and 10 Ma, such as the massive appearance of herbaceous taxa, will be discussed in the context of northern hemisphere cooling and continuing land bridge accessibility during the late Middle and early Late Miocene of Iceland. 6.1 Introduction Early Late Miocene plant-bearing sedimentary rocks in Iceland belong to the Tröllatunga-Gautshamar Formation, and are approximately 10 Ma (Tortonian, early Late Miocene; McDougall et al. 1984). The sedimentary rocks, and particularly the frequently appearing lignites and associated plant fossils, have been known for more than 200 years. They were first studied by O. Olavius in 1775–1777 (Olavius 1780). Later, the sediments and lignites of the TröllatungaGautshamar Formation were studied mainly by geologists (Winkler 1863; Thoroddsen 1896, 1906, 1914, 1915; Bárðarson 1918) and in the course of these T. Denk et al., Late Cainozoic Floras of Iceland, Topics in Geobiology 35, DOI 10.1007/978-94-007-0372-8_6, © Springer Science+Business Media B.V. 2011 291 292 6 The Early Late Miocene Floras (10 Ma) studies, findings of plant fossils from numerous localities were reported. Among these localities are Margrétarfell, Gautshamar, Belti, Torffell, Stekkjargil, Winklerfoss, Gunnustaðagróf, Nónöxl, Bæjarfell, Húsavíkurkleif, Húsavíkurhlíð, Hleypilækur, Fætlingagil, Grýlufoss, Dettifoss, Merkjagil, Hjálparholt, Bæjarlækur, and Nónlækur (see partly Fig. 6.1b, c). Some of the macrofossils were first described by Heer (1859, 1868; collected by J. Steenstrup in 1838–1839, and G. G. Winkler in 1857) and Windisch (1886; collected by C. W. Schmidt and K. Keilhack in 1883) soon after the formation had become better known following Winkler’s publication in 1863, mentioning plant fossils from this area. It was much later that other palaeontologists started to work on fossils from the Tröllatunga-Gautshamar Formation. In the early twentieth century, Bárðarson (1931) reported maple leaves from this formation, but most investigations of the plant-bearing sediments were undertaken during the second half of that century. Pflug (1956), Manum (1962), and Akhmetiev et al. (1978) studied the pollen flora of this formation; Friedrich (1968), Símonarson et al. (1975), Akhmetiev et al. (1978), Friedrich and Símonarson (1982), Blokhina (1992), and Símonarson (1991) published on some macrofossil taxa and preservation forms. Previous studies on pollen from this formation used light microscopy only (Pflug 1956; Manum 1962; Akhmetiev et al. 1978), and accounts dealing with macrofossils have only reported on a single or few taxa (for example Friedrich and Símonarson 1982; Blokhina 1992). Recently, Denk et al. (2005), investigated larger parts of these floras based on macrofossils collected among others by G. Flink in the course of the Swedish Greenland Expedition in 1883, which had not been described earlier. For the present chapter, a combined LM and SEM palynological investigation and a detailed evaluation of macrofossils from all known outcrops of this formation were undertaken. Based on this, we describe palaeoenvironments, vegetation types, and ecological and climatic parameters of possible modern analogues. In addition, we compare the floras of the Tröllatunga-Gautshamar Formation with floras of the older formations in Iceland and with coeval northern hemispheric fossil assemblages and discuss floristic and climatic trends seen within the compared floras. 6.2 Geological Setting and Taphonomy The Tröllatunga-Gautshamar Formation (10 Ma; McDougall et al. 1984) is exposed in the southeastern part of the Northwest peninsula (Fig. 6.1a, b). Sedimentary rocks can be accessed at several outcrops (Margrétarfell, Gautshamar, Belti, Torffell, Stekkjargil, Winklerfoss, Gunnustaðagróf, Nónöxl, Bæjarfell) north of Steingrímsfjörður on the small peninsula bounded by Bjarnarfjörður to the north and Steingrímsfjörður to the south (Fig. 6.1b). Sedimentary rocks are also exposed in Steingrímsfjörður, Húsavíkurkleif locality (Fig. 6.1c; Plate 6.1, 1 and 3) and across the southern part of the Northwest Peninsula, passing the 6.2 Geological Setting and Taphonomy 293 Fig. 6.1 Map showing fossiliferous localities of the 10 Ma formation. (a) bedrock geology (see Fig. 1.10 for explanation), (b) extension of sedimentary rock formation, (c) Húsavíkurkleif and Tröllatunga localities (Geological background modified after Jóhannesson and Sæmundsson 1989; altitudinal lines from Landmælingar Íslands 1994) 294 6 The Early Late Miocene Floras (10 Ma) Tröllatunga localities (including the Hleypilækur, Fætlingagil, Grýlufoss, Dettifoss, Merkjagil, Hjálparholt, Bæjarlækur, and Nónlækur outcrops), over to Króksfjörður (Fig. 6.1b). The sedimentary rocks north of Steingrímsfjörður are fairly similar. They are 7–11 m thick, for the most part composed of brownish to red coloured siltstones and sandstones with occasional tephra layers. The rocks are often organic-rich, showing a more darkish colour with associated lignites. Relatively thick brownish hyaloclastic deposits are often present. One characteristic of this part of the formation is that most of the identifiable plant fossils are preserved as impressions in iron-rich concretions [Iron (II) carbonate (FeCO3)], weathered out from the siltstone units surrounding the lignites. These sedimentary rock types and the typical concretions are the same as found in Húsavíkurkleif south of Steingrímsfjörður (see Plate 6.1, 5 and 7). The sedimentary rocks, especially lignites and organic-rich siltand sandstone suggest accumulation in a lowland environment, characterized by lakes, rivers and floodplains. The thick hyaloclastic units indicate volcanic eruptions in lakes or areas with high groundwater levels. The sedimentary rocks in Húsavíkurkleif are covered by 3–5 m thick lava, built up by a series of thin flows from a single eruption. On top of this lava, the Tröllatunga sediments, 5–30 m thick, can be traced all the way from Húsavíkurkleif, to the southwest, up the Tungudalur valley (Fig. 6.1b, c), and over the highlands toward Króksfjörður. The outcrops here are characterized by thick pyroclastic white to yellow pumice-rich rocks (Plate 6.1, 4 and 6) with increasing thickness towards the highlands. They are thought to have originated from the Króksfjarðar central volcano that was active approximately 10 Ma ago. In this part of the formation, plant fossils are found as compressions in white pyroclastic rocks. The best preserved macrofossils are found in very fine-grained tuff units, reworked in lacustrine settings. Most prominent are sediments related to volcanic activity, of which most are more or less in situ, while some are reworked or deposited in shallow lacustrine settings. Lignites are not characteristic for this part of the formation, but large stems of trees are often found coalified or petrified in the sediments or even vertically standing and connected to palaeosoil, and penetrating the volcanic sediments and/ or overlying lavas. 6.3 Floras, Vegetation, and Palaeoenvironments A total of 99 taxa were recognized from the Tröllatunga-Gautshamar Formation (Table 6.1, Plates 6.1–6.47). One third belongs to the woody angiosperms (34 taxa) and another third to the herbaceous angiosperms (31 taxa). Conifers (incl. Ginkgo) comprise eight taxa and bryophytes and pteridophytes 11 taxa. Lianas are few (only two taxa) and the remaining taxa are unknown types (Fig. 6.2). There is a substantial difference between the number of taxa represented by pollen and macrofossils (90 versus 22). Macrofloras from the Húsavíkurkleif outcrop and other localities north of Steingrímssfjörður are composed of a few taxa only, mostly fragments of 6.3 Floras, Vegetation, and Palaeoenvironments Table 6.1 Taxa recorded for the 10 Ma floras of Iceland Tröllatunga-Gautshamar Formation Taxa Pollen Bryophyta Sphagnum sp. + Lycopodiaceae Lycopodium sp. + Huperzia sp. + Osmundaceae Osmunda parschlugiana + Polypodiopsida Pteridophyta gen. et spec. indet. 1 Equisetaceae Equisetum sp. Polypodiaceae Polypodium sp. 1 + Polypodiaceae gen. et spec. indet. 1 + Polypodiaceae gen. et spec. indet. 3 + Polypodiaceae gen. et spec. indet. 4 + Polypodiaceae gen. et spec. indet. 5 + Ginkgoaceae Ginkgo sp. + Pinaceae Abies sp. + Larix sp. (+) Picea sect. Picea + Pinus sp. 1 (Diploxylon type) + Pseudotsuga sp. (+) Tsuga sp. 1 + Sciadopityaceae Sciadopitys sp. + Apiaceae Apiaceae gen. et spec. indet. 1 + Apiaceae gen. et spec. indet. 2 + Apiaceae gen. et spec. indet. 3 + + Apiaceae gen. et spec. indet. 4 Asteraceae + Artemisia sp. 1 + Artemisia sp. 2 Asteraceae gen. et spec. indet. 1 + + Asteraceae gen. et spec. indet. 2 Asteraceae gen. et spec. indet. 3 + Betulaceae Alnus cecropiifolia (+) 3 Betula islandica + Carpinus sp. 2 + Corylus sp. + Calycanthaceae aff. Calycanthaceae + 295 Leaves RP Other DM 1a 1a 1a + + + + 1a 1a 1a 1a 1a 1a 1a 1a 1b + + + 2a 2a 2a 2a 2a 2a 1b 1b 1b 1b 1a 1a 1a 1a 1a + + (+) D 1a, 2a 1a 2a 2a 1b (continued) 296 Table 6.1 (continued) Tröllatunga-Gautshamar Formation Taxa Caprifoliaceae Lonicera sp. 1 Lonicera sp. 2 Lonicera sp. 3 Caryophyllaceae Caryophyllaceae gen et. spec. indet. 1 Caryophyllaceae gen et. spec. indet. 2 Caryophyllaceae gen et. spec. indet. 3 Chenopodiaceae Chenopodium sp. Chenopodiaceae gen. et spec. indet. 1 Chenopodiaceae gen. et spec. indet. 2 Cyperaceae Cyperaceae gen. et spec. indet. A Ericaceae Arctostaphylos sp. Rhododendron aff. ponticum Ericaceae gen. et spec. indet. 1 Vaccinium sp Fagaceae Fagus sp. Trigonobalanopsis sp. Juglandaceae Cyclocarya sp. Pterocarya sp. Liliaceae Liliaceae gen. et spec. indet. 2 Liliaceae gen. et spec. indet. 3 Lythraceae Decodon sp. Nympheaceae cf. Nuphar sp. Plantaginaceae aff. Plantago lanceolata Platanaceae Platanus sp. Poaceae Poaceae gen. et spec. indet. 1 Polygonaceae Polygonum sect. Aconogonon sp. Rumex sp. Ranunculaceae Anemone sp. Ranunculus sp. 1 6 The Early Late Miocene Floras (10 Ma) Pollen + + + + + + + + + Leaves RP Other DM 1b 1b 1b 1b 1b 1b 1b 1b 1b + + 1b 1b 1a?, 2a 1b 1b 2b, 3 2b, 3 (+) + + + + + (+) (+) + + + + + + + + + + + + + 2a 2a 2a 2a 1b 1b 1b 2a 1b, 2a 1b 1b 1b, 2a 1b (continued) 6.3 Floras, Vegetation, and Palaeoenvironments Table 6.1 (continued) Tröllatunga-Gautshamar Formation Taxa 297 Pollen Leaves RP Other DM Thalictrum sp. 1 + 1b Ranunculaceae gen. et spec. indet. 1 + 1b Ranunculaceae gen. et spec. indet. 2 + 1b Rosaceae Rosaceae gen. et spec. indet. Type A (+) 7 + 1b Crataegus sp. + Sanguisorba sp. + 1b, 2a Salicaceae Salix gruberi (+) 2 + 1a Sapindaceae Acer crenatifolium subsp. islandicum (+) 3 + +D 2a Acer askelssonii (+) 3 + +D 2a Smilacaceae Smilax sp + 1b Tiliaceae Tilia sp. + 1b?, 2a Ulmaceae Ulmus sp. + 2a Vitaceae Parthenocissus sp. + 1b Incertae sedis - Magnoliophyta Dicotylophyllum sp. B + ? Dicotylophyllum sp. C + ? Pollen type 8 + ? Pollen type 9 + ? Pollen type 10 + ? Pollen type 11 + ? Pollen type 12 + ? Pollen type 13 + ? Pollen type 14 + ? Pollen type 15 + ? Pollen type 16 + ? Pollen type 17 + ? Pollen type 18 + ? Pollen type 19 + ? Pollen type 20 + ? L leafy axis, A fruit attached to leafy axis, D fruit dispersed, RP reproductive structure, + organ present, + original description of species based on this organ, (+) organ belonging to genus but uncertain to which of the species, (+) 2 indicating number of pollen types possibly belonging to the eponymous morphotaxon, DM Dispersal mode: 1a wind long distance (anemochory), 1b bird long distance (endozoochory), 2a wind short distance (anemochory), 2b animals short distance (exozoochory), 3 dyschory 298 6 The Early Late Miocene Floras (10 Ma) Fig. 6.2 Distribution of life forms and higher taxa among the plants recovered from the 10 Ma sedimentary rock formation. Height of columns indicates number of taxa Osmunda fronds and axes of Equisetum with an admixture of Salix leaves and Alnus strobili. Betula, Pterocarya, and Acer are less common. Azonal or riparian elements and the type of the sedimentary rocks reflect lowland environments dominated by lakes, rivers, and floodplains. South of Húsavíkurkleif, the macrofloras in the Tröllatunga area are richer and composed mostly of Acer, Alnus, Cyclocarya, Rhododendron, Rosaceae, and Vaccinium. Other taxa include Betula, Smilax, Arctostaphylos, Picea, and Pseudotsuga. The diversity and heterogeneity of the fossil flora and the type of sedimentary rocks suggest that these assemblages reflect zonal vegetation, growing on generally drier substrates with a few widely spaced shallow lakes or ponds in an elevated area that was greatly affected by volcanic activity. Combined macrofossil and palynological evidence allow for a more differentiated reconstruction of the early Late Miocene vegetation types and environments. Nine main vegetation types can be distinguished (Table 6.2, Fig. 6.3). Azonal riparian vegetation is represented by plants characteristic of aquatic and subaquatic environments, and backswamp forests and temporarily flooded lake margins. Temporarily flooded forests were quite diverse, containing trees, shrubs, true lianas, and herbaceous plants in forest gaps. Warmth-loving Cupressaceae as encountered in the older formations (see Chaps. 4 and 5) are entirely absent from the TröllatungaGautshamar Formation and large trees in temporally flooded riparian forests were probably species of Pterocarya, Alnus, and Salix, and possibly also some Rosaceae. Table 6.2 Vegetation types and their components during the late early Late Miocene of Iceland Vegetation types 10 Ma Aquatic vegetation Decodon sp. Lemnaceae gen. et spec. indet. 1 cf. Nuphar sp. Ranunculaceae gen. et spec. indet. 1, 2 Backswamp forests and temporally flooded lake margin Sphagnum sp. Equisetum sp. Osmunda parschlugiana Alnus cecropiifolia aff. Calycanthaceae Chenopodiaceae aff. Chenopodium sp. Chenopodiaceae gen. et spec. indet. 1-2 Cyperaceae Decodon sp. Parthenocissus sp. Poaceae gen. et spec. indet. 1 Pterocarya sp. Ranunculaceae gen. et spec. indet. 1, 2 Salix gruberi Smilax sp. Levée forests and well-drained lake margins Lycopodium sp. Polypodium sp. Polypodiaceae gen. et spec. indet. 1-4 Acer crenatifolium subsp. islandicum Alnus cecropiifolia Crataegus sp. Lonicera sp. 1-3 Parthenocissus sp. Platanus sp. Poaceae gen. et spec. indet. 1 Rosaceae gen. et spec. indet. 1-7 AZONAL VEGETATION Smilax sp. Ulmus sp. Well-drained lowland forests and lake margins Equisetum sp. Osmunda parschlugiana Tsuga sp. Acer askelssonii Acer crenatifolium subsp. islandicum Alnus cecropiifolia Betula islandica aff. Calycanthaceae Carpinus sp. 2 Corylus sp. Crataegus sp. Cyperaceae Liliaceae gen. et spec. indet. 2-3 Lonicera sp. 1-3 Parthenocissus sp. Platanus sp. Pterocarya sp. Rhododendron aff. ponticum Rosaceae gen. et spec. indet. 1-7 Trigonobalanopsis sp. † Ulmus sp. Rocky outcrop forests Lycopodium sp. Lycopodiaceae aff. Huperzia sp. Ginkgo sp. Larix sp. Picea section Picea sp. Pinus sp. 1 Pseudotsuga sp. Tsuga sp. Plantago lanceolata type Poaceae gen. et spec. indet. 1 Rosaceae gen. et spec. indet. 1-7 Thalictrum sp. 1 Foothill forests Lycopodium sp. Polypodium sp. Polypodiaceae gen. et spec. indet. 1-4 Ginkgo sp. Pinus sp. 2 Pseudotsuga sp. Tsuga sp. Sciadopitys sp. Acer askelssonii Acer crenatifolium subsp. islandicum Alnus cecropiifolia Betula islandica Carpinus sp. 2 cf. Cyclocarya sp. Corylus sp. Fagus sp. Lonicera sp. 1, 2 Platanus sp. Rhododendron aff. ponticum Rosaceae gen. et spec. indet. 1-7 Rosaceae gen. et spec. indet. type A Tilla sp. Trigonobalanopsis sp. † Meadows and shrublands Huperzia sp. Anemone sp. Apiaceae gen. et spec. indet. 1-4 Arctostaphylos sp. Artemisia sp. 1, 2 Asteraceae gen. et spec. indet. 1-3 Caryophyllaceae gen. et spec. indet. 1-3 Cyperaceae Poaceae gen. et spec. indet. 1 ZONAL VEGETATION Ranunculaceae gen. et spec. indet. 1, 2 Ranunculus sp. Rosaceae gen. et spec. indet. 1-7 Rumex sp. Thalictrum sp. 1 Vaccinium sp. Montane forests Lycopodium sp. Polypodium sp. Polypodiaceae gen. et spec. indet. 1-4 Ginkgo sp. Abies sp. Larix sp. Picea section Picea sp. Pinus sp. 1 Pseudotsuga sp. Tsuga sp. Acer crenatifolium subsp. islandicum Cyclocarya sp. Fagus sp. Lonicera sp. 1, 2 Rhododendron aff. ponticum Sciadopitys sp. Tilia sp. Ulmus sp. Ravine forests Sphagnum sp. Osmunda parschlugiana Polypodium sp. Polypodiaceae gen. et spec. indet. 1-4 Abies sp. Tsuga sp. Calycanthus sp. Corylus sp. Fagus sp. Rosaceae gen. et spec. indet. 1-5 Tilia sp. Ulmus sp. The palaeoecology of fossil species is reconstructed from their sedimentological context and ecology of modern analogues 300 6 The Early Late Miocene Floras (10 Ma) Fig. 6.3 Schematic block diagram showing palaeo-landscape and vegetation types for the early Late Miocene of Iceland. See Table 6.2 for species composition of vegetation types Areas with lower ground water tables may have been richer in tree species (Acer spp., Platanus, Rosaceae etc.) and the diversity of these forests probably further increased towards the well-drained mountain slopes. Evergreen understorey or forest gap elements such as Rhododendron aff. ponticum and mesophytic trees (Fagus, Tilia) were characteristic of well-drained forests from the lowlands to higher elevations (Fig. 6.4). Also, the conifer species (including Ginkgo) recorded for the 10 Ma formation were most likely elements of these well-drained zonal forests. The presence of open landscapes is indicated by the substantial amount of herbaceous (including grasses) elements in the palynological record and macrofossils of small-leaved shrubs of small stature most likely belonging to the Ericaceae (Vaccinium, Arctostaphylos). This is a novel feature of the Icelandic landscape that has not been recorded in the older sedimentary formations (Fig. 6.3). Herbs and grasses formed meadows and were components of shrubland vegetation and rocky outcrop forests on poor soils (Table 6.2; Fig. 6.5). Families represented by herbaceous taxa (Asteraceae, Caryophyllaceae etc.) also play an important role in the modern Icelandic vegetation. 6.3 Floras, Vegetation, and Palaeoenvironments Fig. 6.4 Schematic transect of a well-drained lowland forest 301 302 6 The Early Late Miocene Floras (10 Ma) Fig. 6.5 Schematic transect of diverse vegetation showing well-drained lowland forest, forest edge and meadow 6.4 Ecological and Climatic Requirements of Modern Analogues 303 6.4 Ecological and Climatic Requirements of Modern Analogues The taxa recovered from the 10 Ma formation appear to signal a marked change in ecological and climatic conditions as compared to the older (15 and 12 Ma) floras. Warmth-loving conifers (Cupressaceae) and angiosperms (Lauraceae, Magnoliaceae) are absent from the 10 Ma formation and instead shrubs and herbaceous taxa that are typical of cool-temperate conditions are present. Overall, this suggests cooler conditions for the 10 Ma formation and a more diverse vegetation (Fig. 6.3). Climatic properties of all the taxa are listed in Appendix 13.1, Chap. 13; brief descriptions of Sciadopitys and Betula islandica are given in Chap. 5 and of Fagus and Platanus in Chap. 4. Ginkgo, the maidenhair tree, is represented by a single living species, G. biloba L. that is known in only a few populations in low coastal regions and interior mountains along the Yangtze River in Eastern China. It is not entirely clear whether these populations are in fact natural ones or whether they had been planted by monks. In semi-wild stands, Ginkgo grows in disturbed micro-sites, such as stream banks, steep rocky slopes and the edges of exposed cliffs (Del Tredici et al. 1992). In addition, Del Tredici (1989) suggested that Ginkgo is a gap opportunist, i.e. a tree that can cope with shady conditions in the understorey until it becomes a canopy tree when a gap occurs. Royer et al. (2003) analysed more than 50 fossil sites with Ginkgo ranging in age from the Late Cretaceous to the Middle Miocene, mostly from Arctic areas. Based on sedimentological and floristic context, they concluded that ginkgoes were largely confined to disturbed stream margins and levée environments. In the northern hemisphere, Ginkgo shifted from high latitudes to lower latitudes from the Paleocene onward. It became confined to Eurasia by the end of the Miocene (Denk and Velitzelos 2002). In Europe, Ginkgo is a very rare element during the Miocene, found as single leaves or leaf fragments (Denk and Velitzelos 2002; Hably and Marrón 2007; Kvaček et al. in press). This situation, and the one in Iceland, may be substantially different from the one reported by Royer et al. (2003) where ginkgoes in many cases are abundant elements of the fossil assemblages. The sparse occurrence of Ginkgo in Miocene assemblages of Iceland may indicate it was an element of well-drained (light) forests (cf. Fig. 6.4) at some distance from the area of sedimentation. Extant Ginkgo biloba (cultivated) grows in a wide variety of climates, ranging from Mediterranean to cold temperate (Royer et al. 2003). Carpinus comprises about 25 species with a northern hemispheric disjunct distribution (Flora of North America Editorial Committee 1997). Most species occur in eastern Asia and grow in temperate to subtropical mixed forests, often on moist mountain slopes, but also in edaphically dry places (Flora of China Editorial Committee 1999). In China, the vertical distribution of Carpinus is from 200 to 2,900 m a. s. l. In North America, a single species, C. caroliniana Walter is an element of rich deciduous lowland forests (0–300 m) along stream banks. In western Eurasia, a few species are found in rich lowland forests and in Submediterranean light forests. The genus occurs in a wide range of climates, 304 6 The Early Late Miocene Floras (10 Ma) mostly in Cfa climates and occasionally in Csa/Cwa climates with MAT 2.5–28.2°C (Thompson et al. 1999). Cyclocarya comprises a single modern species, C. paliurus (Batalin) Iljinsk., which is endemic to China. It grows in moist mountain forests from 400 to 2,500 m a. s. l. (Flora of China Editorial Committee 1999) under a Cfa climate with MAT 3.5–20.5°C. Decodon is represented by a single living species, D. verticillatus (L.) Elliott, endemic to eastern North America (Florida to Nova Scotia). It is a suffrutescent plant that forms dense stands in shallow water around lakes and Taxodium-Nyssa swamp forests (Kvaček and Sakala 2006). This genus had a much wider distribution but similar ecological range during the Tertiary (Kvaček and Sakala 2006). It is clearly an azonal element that is less useful for climate estimates. The modern species mainly occurs in a (warm) temperate humid Cfa climate (extending into Dfb) with MAT 2.1–19.8°C. Smilax from the 10 Ma formation in Iceland is similar to the modern woody vine S. rotundifolia L. from eastern North America, which thrives in dry to moist, often riparian forests. This species, and most of the remaining species of the genus that do not occur in a Mediterranean Csa climate, thrive under a warm temperate fully humid Cfa climate with MAT 2.1–19.8°C. Tilia is a typical northern hemisphere temperate tree genus with about 25 species in North America, Europe and Asia. It is a component of well-drained mixed hardwood forests. The European and Asian Minor species Tilia platyphyllos typically grows in a Cfb climate with MAT 3.4–14°C. Tilia americana L. native of eastern North America occurs in cold to warm temperate Dfb to Cfa/b climates (Kottek et al. 2006) with MAT 1.1–16.1°C (Thompson et al. 2000). The herbaceous taxa recorded from the Tröllatunga-Gautshamar Formation are not indicative of particular climate types. However, all of them are, among others, elements of modern Arctic-Alpine vegetation types. Similarly, small-leaved types of Ericaceae (Vaccinium, Arctostaphylos) presently thrive under various climate types (Cfb to Dfc and ET; Kottek et al. 2006) with MAT from far below the freezing point up to ca 12–14°C (V. uliginosum L., V. vitis-idaea L., Arctostaphylos uva-ursi (L.) Spreng.). The plant assemblage recovered from the 10 Ma Tröllatunga-Gautshamar Formation indicates diverse environmental conditions reflecting a range of climate types. Lowlands, although devoid of warmth-loving Taxodiaceae, contained Platanus, pointing to warm temperate (Cf climates) conditions. Based on the modern distribution of Platanus, this genus is limited by temperature (overall warm, no severe winter frosts) rather than precipitation (Nixon and Poole 2003; Cfa and Csa climates according to Köppen). However, the eastern North American P. occidentalis L. extends into regions with Dfa and Dfb climates (Thompson et al. 1999). Given the position of Iceland in the northern North Atlantic, a fully humid climate can be assumed for the Miocene. However, mountains of up to 2,000 m provided a barrier to humid air and may have caused more continental conditions in the interior, as is the case today. In an overall warm climatic setting as found in the 15 and 12 Ma time periods, this might have caused only little variation in the vegetation. 6.5 Migration Routes and Taxonomic Affinities of Newcomers 305 Cooler conditions at 10 Ma may have increased the effect of relief, favouring herbaceous and shrubland vegetation. In coastal lowlands and on moist mountain slopes, rich hardwood forests could thrive. The presence of Fagus and Rhododendron ponticum /R. maximum in such forests strongly indicate warm temperate conditions (Cfb climates). Meadows and shrublands could occupy open patches in the forest vegetation because of edaphic differences and outcompeted forest vegetation in drier/cooler places in the interior and at higher elevations (Fig. 6.3). MAT in the 10 Ma formation would have been 8–10°C in lowlands and slightly cooler on moist foothills. Variants of this climate types would have been caused by elevation (cooler) and/or rain shelter in the interior (drier). 6.5 Migration Routes and Taxonomic Affinities of Newcomers: Implications for Continuous Land Bridge Availability For the 10 Ma Tröllatunga-Gautshamar Formation, no clear pattern emerges favouring migration to Iceland from either Europe or North America (Denk et al. 2005; Grímsson and Denk 2007). Most taxa that first arrived in the 10 Ma formation cannot be identified below the genus or even subfamily level. Modern higher taxa, to which the fossils can be assigned, mostly show a Eurasian-North American distribution. Therefore, most of the new taxa could have migrated to Iceland from either North America/Greenland or Europe. Exceptions are Ginkgo and the extinct Fagaceous genus Trigonobalanopsis. Ginkgo was widespread in the Early Tertiary “Brito-Arctic Igneous Province” (Boulter and Kvaček 1989) in the so-called “Polar Broadleaved Deciduous Forests” (Mai 1995). In North America, the genus persisted until the late Early Miocene (western United States, Eagle Creek Formation, Chaney 1920; Manchester 1999). In contrast, Ginkgo persisted in Europe until the Pliocene (Denk and Velitzelos 2002). This may indicate that Ginkgo arrived from Europe sometime between 12 and 10 Ma. Little is known about how Ginkgo is dispersed. For Mesozoic ginkgoes, it has been suggested that terrestrial reptiles dispersed the large fleshy fruits (Tiffney 1986, 2004), while modern Ginkgo is probably dispersed by mammals (Del Tredici et al. 1992). Trigonobalanopsis is an extinct fagaceous genus that was widespread in the European Tertiary from the Eocene to the Late Miocene (Kvaček and Walther 1988; Walther and Zetter 1993). In contrast, it has no known fossil record in North America. The genus formed part of warm temperate mixed mesophytic and broadleaved deciduous forests in the Miocene. By the Late Miocene, Trigonobalanopsis had become a rare element in Europe. Thus, available evidence points to the migration of this relict taxon from Europe to Iceland between 12 and 10 Ma. Like Fagus, Trigonobalanopsis had little potential for long distance dispersal. Cyclocarya is at present confined to mixed mesophytic forests of southeastern China. Unequivocal fossils of winged fruits are known from the Paleocene of North America (Manchester 1999); in Europe and Asia, the genus has a fossil record from the Oligocene to the Late Pliocene (Mai 1995). Leaflets from Tröllatunga assigned to 306 6 The Early Late Miocene Floras (10 Ma) Cyclocarya sp. are very similar to C. ezoana (Tanai and N. Suzuki) Wolfe and Tanai from the Middle Miocene Seldovia Point Flora, Alaska (Wolfe and Tanai 1980). Cyclocarya ezoana was originally described from the Middle Miocene of Japan (Tanai and Suzuki 1963). Similar types are also known from the Early Miocene of Germany (C. cyclocarpa (Schlecht.) Iljinsk.; Budantsev 1994; Mai 1995). Based on the present data, it is difficult to determine whether Cyclocarya migrated to Iceland from Europe or North America. A migration route from North America has previously been suggested for Fagus friedrichii that has a disjunct distribution in the Middle Miocene of Iceland and the Seldovian Point Flora from Alaska (see Chap. 4; Grímsson and Denk 2005). In view of the close similarity of leaves from the Tröllatunga locality and the late Early/early Middle Miocene Seldovian Point Flora, a migration from North America seems more probable. However, since leaf fossils of Cyclocarya are also known from Europe, a migration from the east cannot entirely be ruled out. Decodon is a monotypic genus in eastern North America with a single species, D. verticillatus. It is represented by pollen in the Tröllatunga-Gautshamar Formation in Iceland and leaves unambiguously belonging to Decodon are known from the Seldovian Point Flora in Alaska (Wolfe and Tanai 1980).The genus was fairly common in Eurasia from the Eocene to the Pliocene and in North America from the Eocene onwards (Manchester 1999). Thus, a particular migration route to Iceland cannot be determined. Only a few taxa are indicative of a particular migration route of plants to Iceland during the period 12–10 Ma. Of these, Ginkgo and Trigonobalanopsis are more likely to have colonized Iceland from the east. Neither taxon is dispersed by wind or birds over large distances, which suggests the presence of a functioning North Atlantic land bridge between Europe and Iceland between 12 and 10 Ma (for a definition of “land bridge” see Chap. 12). In contrast, Cyclocarya probably reached Iceland from the west. The seeds of Cyclocarya are transported by wind over short distances, suggesting a land bridge also for the western link to the American continent via Greenland. 6.6 Origin of Herbaceous Vegetation in Iceland Herbaceous plants are very rare in the fossil record of Iceland prior to 10 Ma (see Chaps. 4, 5). In Europe, families comprising mainly herbaceous taxa become more common in the fossil record partly in the Oligocene (Cyperaceae, Ranunculaceae) but mainly in the course of the Miocene (Asteraceae, Caryophyllaceae, Chenopodiaceae, Rosaceae herbaceous types; Mai 1995). This may be related to more continental conditions originating after the Oligocene (e.g. uplift of the Tibetan Plateau) and general cooling due to the expansion of the Antarctic Ice Sheet (Zachos et al. 2001), which in turn opened up new niches for herbaceous plants and increased the probability of them becoming fossilized. The sudden appearance of herbaceous plants in the global fossil record after the Oligocene does not reflect the evolutionary histories of these plant groups. In fact, many herbaceous lineages originated much earlier (Late Cretaceous, Early Tertiary; cf. Magallón et al. 1999). The more prominent presence in the fossil record is rather due to the increased availability of suitable 6.7 Comparison to Coeval Northern Hemispheric Floras 307 niches resulting from tectonic and climatic changes (Zachos et al. 2001). In the same way, the large proportion of herbaceous taxa in the Icelandic fossil record may reflect the opening up of new niches as a result of cooling in the northern North Atlantic (Chap. 13). Changed environmental conditions would have increased the competitiveness of herbaceous plants against more thermophilic woody taxa. Such niches may not have been available during the warm 15 and 12 Ma time intervals. 6.7 Comparison to Coeval Northern Hemispheric Floras The diverse assemblage of the 10 Ma Tröllatunga-Gautshamar Formation shows similarities to a flora from Arctic North America (Lignite Creek Flora, Alaska; Homerian Stage, Usibelli Group, Zone L-1, L-2; Leopold and Liu 1994; White et al. 1997; Appendix 6.1). Both the Icelandic and the Alaskan floras lack warmthloving conifers belonging to the Cupressaceae s.l. and share several Pinaceous taxa and Sciadopitys. A high degree of similarity is also seen among the angiosperms. Taxa in the Lignite Creek flora that are missing in Iceland are Araliaceae, Castanea, Elaeagnus and Liquidambar. In contrast, Smilax and Ginkgo are recorded in the Icelandic flora but absent from the Alaskan pollen assemblage. Despite the appreciable similarity between the two floras, the change from the older Middle Miocene floras to the early Late Miocene flora is more pronounced in Iceland than in Alaska. While a major floristic change occurred between 15 and 12 Ma in Arctic North America (see Chap. 5, Appendix 5.1) this change came later in Iceland, between the late Middle Miocene (12 Ma) and early Late Miocene (10 Ma). Only few early Late Miocene floras are available from North America and western Eurasia. The Achldorf flora (southern Germany; Knobloch 1986; Gregor 1986; Appendix 6.1) is one of the most diverse floras of the “Upper Freshwater Molasse” and may serve as an example for a mid-latitude flora. The flora is slightly older than Tröllatunga (Sarmatian to Pannonian, Central European Mammal Zone MN9; Unger 1986) and is possibly intermediate in age between the 12 Ma and 10 Ma floras of Iceland. A number of genera are shared between the 12 and 10 Ma floras of Iceland and Achldorf (e.g. Platanus, Acer, various Betulaceae and Fagaceae, Pterocarya, Smilax, and Ulmus). However, genera such as Acer and Quercus are markedly richer in species. Representatives of the genus Quercus mainly belong to the Quercus infrageneric group Cerris (Denk and Grimm 2009, 2010) which has a more southern distribution than the white (or red) oaks reported from Iceland (Denk et al. 2010). In addition, the warmth-loving Cupressaceae (Taxodium), Lauraceae, and Fabaceae distinguish the Achldorf flora from the contemporaneous Icelandic floras. Overall, the early Late Miocene flora of Iceland represents a diverse vegetation. Broadleaved deciduous forests in Iceland are similar to coeval vegetation types found both in Arctic North America and the mid-latitudes of Europe. Compared to mid-latitude floras in western Eurasia, they are poorer in species and lack several warmth-loving elements. The prominent number of herbaceous taxa and shrubs as seen in Iceland may reflect a stronger response of vegetation to a cooling climate at high latitudes than at mid-latitudes. 308 6 The Early Late Miocene Floras (10 Ma) 6.8 Summary This chapter presents a complete list of taxa for the 10 Ma Tröllatunga-Gautshamar Formation in northwestern Iceland. Compared to the older 12 Ma Brjánslækur-Seljá Formation, the 10 Ma formation is poorer in forest-building tree taxa (both conifers and angiosperms). However, in terms of the total number of taxa (spore, pollen, and macrofossil taxa), this is the most diverse fossil assemblage of Iceland. This diversity mirrors a diversified vegetation, including lowland riparian and well-drained forests, upland forests as well as meadows and shrublands with a markedly “modern” appearance. Many of the new elements recorded for the 10 Ma formation are herbaceous plants that (at the genus level) are also found in the modern vegetation of Iceland. The co-occurrence of humid warm temperate forests containing exotic elements (Cyclocarya, Platanus etc.) with meadows and shrublands containing taxa that are able to cope with cold conditions (various herbaceous taxa; Arctostaphylos, Vaccinium) possibly marks a climatic and ecological shift in Iceland in the context of gradual global cooling during this time. Specifically, herbs and small shrubs may have become more competitive at higher elevations and in the interior regions of Iceland due to cooler and/or drier conditions. Migration routes to Iceland were both from the west and the east. A number of taxa not recorded in older formations in Iceland are not dispersed by wind or birds over long distances (Ginkgo, Trigonobalanopsis, Cyclocarya), which is suggestive of an active land bridge between Iceland and the adjacent continents between 12 and 10 Ma. Appendix 6.1 309 Appendix 6.1 Floristic composition of the 10 Ma sedimentary formation of Iceland compared to contemporaneous northern hemispheric mid- and high-latitude floras from North America and western Eurasia. Tröllatunga-Gautshamar flora, Iceland [ca 65°37¢N 21°41¢W] 10–9 Ma This study 3 Equisetum sp. 1 Lycopodium sp. 1 1,3 1 1 1 1 1 1 1 1 1,3 1,3 1 1 1 1 1-3 1-3 1-3 1 1 3 1 1 1 1 1 1-3 1 1 1 1 1 1 Huperzia sp. Osmunda parschlugiana Polypodiaceae gen. et spec. indet. 1 Polypodiaceae gen. et spec. indet. 3 Polypodiaceae gen. et spec. indet. 4 Polypodiaceae gen. et spec. indet. 5 Polypodium sp. 1 Pteridophyta gen. et spec. indet. 1 Sphagnum sp. Ginkgo sp. Larix sp. Picea sect. Picea Pinus sp. 1 Pseudotsuga sp. Sciadopitys sp. Tsuga sp. 1 Acer askelssonii Acer crenatifolium subsp. islandicum Alnus cecropiifolia Anemone sp. Apiaceae gen. et spec. indet. 1-4 Arctostaphylos sp. Artemisia sp. 1 Artemisia sp. 2 Asteraceae gen. et spec. indet. 1 Asteraceae gen. et spec. indet. 2 Asteraceae gen. et spec. indet. 3 Betula islandica aff. Calycanthaceae Carpinus sp. Caryophyllaceae gen et. spec. indet. 1 Caryophyllaceae gen et. spec. indet. 2 Caryophyllaceae gen et. spec. indet. 3 Chenopodiaceae gen et. spec. indet. 1 1 1 1 3 3 1 3 3 1 1 1 1 1 1 1 1 3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1,3 1 1 Chenopodiaceae gen et. spec. indet. 2 Chenopodium sp. Corylus sp. Cyclocarya sp. Cyperaceae gen. et spec. indet. A Decodon sp. Dicotylophyllum sp. B Dicotylophyllum sp. C Ericaceae gen. et spec. indet. 1 Fagus sp. Lemnaceae gen. et spec. indet. Liliaceae gen. et spec. indet. 2 Liliaceae gen. et spec. indet. 3 Lonicera sp. 1 Lonicera sp. 2 Lonicera sp. 3 cf. Nuphar sp. Parthenocissus sp. Platanus sp. aff. Plantago lanceolata Poaceae gen. et spec. indet. 1 Pollen type 8 Pollen type 9 Pollen type 10 Pollen type 11 Pollen type 12 Pollen type 13 Pollen type 14 Pollen type 15 Pollen type 16 Pollen type 17 Pollen type 18 Pollen type 19 Pollent type 20 Polygonum sect. Aconogonon sp. Pterocarya sp. Ranunculaceae gen. et spec. indet. 1 Ranunculaceae gen. et spec. indet. 2 (continued) 310 Tröllatunga-Gautshamar flora (continued) 1 Ranunculus sp. 1 1-3 1,3 1 1,3 1 3 1 1 1 1 3 Rhododendron aff. ponticum Rosaceae gen. et spec. indet. type A Rumex sp. Salix gruberi Sanguisorba sp. Smilax sp. Thalictrum sp. 1 Tilia sp. Trigonobalanopsis sp. Ulmus sp. Vaccinium sp. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 6 The Early Late Miocene Floras (10 Ma) Diervilla/Weigelia Elaeagnus sp. Ericales indet. Fraxinus sp. Gramineae Juglans sp. Liquidambar sp. Magnolia sp. Melia sp. Onagraceae Ostrya/Carpinus sp. Polygonum persicaria Populus sp. Prunus sp. Pterocarya sp. Pterocarya sp. Rhus sp. Rosaceae Salix sp. Sparganium sp. Thalictrum sp. Tilia sp. Ulmus/Zelkova sp. Lignite Creek flora [ca 64°04¢N 148°13¢W] 11.3–9.7 Ma (Leopold and Liu 1994; White et al. 1997) 1 Cyathea sp. 1 Lycopodium cf. L. alopecuroides 1 Lycopodium cf. L. complanatum 1 Osmunda sp. 1 Selaginella sp. 1 Sphagnum sp. 1 Abies cf. A. grandis 1 Cedrus sp. 1 Larix/Pseudotsuga sp. 1 Picea sp. 1 Pinus sp. 1 Sciadopitys sp. 1 Tsuga cf. canadensis 1 Tsuga cf. heterophylla 1 Tsuga cf. mertensiana 1 Acer sp. 1 Alnus cf. firma 1 Alnus sp. 1 Ambrosia sp. 1 Araliaceae 1 Artemisia sp. 1 Betula sp. 1 Caprifoliaceae 1 Castanea sp. cf. Crataegus sp. 1 1 Chenopodiineae Compositae 1 1 1 1 Cornus sp. Corylus sp. Cyclocarya sp. Achldorf flora [48°25¢N 12°21¢E] MN8, MN9 (Unger 1986; Knobloch 1986; Gregor 1986; Schmitt 1986) 3 Pinus sp. 2 Pinus aff. thomasiana 3 Taxodium dubium 2 Taxodium hantkei 3 ?Platanus leucophylla 3 Acer cf. ginnala 3 Acer integrilobum 2 Acer jurenaky vel pseudoplatanus 2 Acer cf. monspessulanum vel italium 2,3 Acer tricuspidatum Acer sp. 2 3 Alnus alnoidea 2 Alnus kefersteinii 3 Alnus menzelii 2 Amentiferae 3 Betula subpubescens 2 Betula cf. longisquamosa 2,3 Carpinus cf. grandis 2 Carpinus kisseri 3 Carya aff. serraefolia (continued) References Achldorf flora (continued) 3 2,3 3 2 2 3 3 3 3 3 3 3 3 2 3 2 3 2 3 2 2 2 2 2 3 Carya minor Carya sp. Cephalotaxus cf. stockleinea cf. Clematis vitalba aff. Corylopsis urselensis Crataegus cf. neckerae Cyperaceae vel Poaceae Daphnogene bilinica Dicotylophyllum cf. oeningense Dicotylophyllum sp. 1-7 cf. Diospyros aff. pannonica cf. Ficus truncata Gleditsia lyelliana Gleditsia knorrii Hemiptelea vel Zelkova sp Leguminocarpum sp. Liquidambar europaea Liquidambar cf. magniloculata Myrica lignitum Myrica ceriferiformis Nymphaea sp. Ostrya scholzii Ostrya sp. Paliurus thurmanni Palirus tiliaefolius 3 2 2 3 3 3 3 3 2 3 3 3 2 3 3 2 2 3 3 2 2 Parrotia pristina Pterocarya limburgensis Quercus cerrisaecarpa Quercus gregori Quercus cf. kubinyi Quercus kucerae Quercus pontica-miocenica Quercus pseudocastanea Quercus sapperi Quercus schoetzii Quercus sp. Robinia regeli Rubus sp. Salix sp. Smilax sp. 1-2 cf. Symplocos lignitarum Trapa cf. heeri Ulmus pyramidalis Zelkova praelonga Zelkova cf. ungeri Zelkova sp. 311 Boldface indicates that the genus is present in the Tröllatunga-Gautshamar Formation. Grey shading indicates that the genus is present in the older Brjánslækur-Seljá Formation (12 Ma) or the younger Skarðsströnd-Mókollsdalur Formation (9–8 Ma). 1 based on pollen, spores; 2 based on leaves and/or fruit/seed fossils; 3 based on leaf fossils. References Akhmetiev, M. A., Bratzeva, G. M., Giterman, R. E., Golubeva, L. V., & Moiseyeva, A. I. (1978). Late Cenozoic stratigraphy and flora of Iceland. Transactions of the Academy of Sciences USSR, 316, 1–188. Bárðarson, G. G. (1918). Um surtarbrand. Andvari, 43, 1–71. Bárðarson, G. G. (1931). Trjáblað úr surtarbrandslögum. Náttúrufræðingurinn, 1, 2. Blokhina, N. I. (1992). Fossil woods from the Tertiary deposits of Iceland. In J. Kovar-Eder. (Ed.), Palaeovegetational development in Europe an regions relevant to its palaeofloristic evolution. Proceedings of the Pan-European Palaeobotanical Conference Vienna 1991 (pp. 111–115). Vienna: Museum of Natural History. Boulter, M. C., & Kvaček, Z. (1989). The Palaeocene flora of the Isle of Mull. Special Papers in Palaeontology, 42, 1–149. Budantsev, L. (Ed.). (1994). Magnoliophyta fossilia rossiae et civitatum finitimarum, vol. 3, Leitneriaceae – Juglandaceae. Saint Petersburg: Komarov Botanical Institute Russian Academy of Sciences. 118 pp. Chaney, R. W. (1920). The flora of the Eagle Creek Formation. Contributions from Walker Museum, 2, 115–181. 312 6 The Early Late Miocene Floras (10 Ma) Del Tredici, P. (1989). Ginkgos and multituberculates: Evolutionary interactions in the tertiary. Bio Systems, 22, 327–339. Del Tredici, P., Ling, H., & Yang, G. (1992). The Ginkgos of Tian Mu Shan. Conservation Biology, 6, 202–209. Denk, T., & Grimm, G. W. (2009). Significance of pollen characteristics for infrageneric classification and phylogeny in Quercus (Fagaceae). International Journal of Plant Sciences, 170, 926–940. Denk, T., & Grimm, G. W. (2010). The oaks of western Eurasia: Traditional classifications and evidence from two nuclear markers. Taxon, 59, 351–366. Denk, T., & Velitzelos, D. (2002). First evidence of epidermal structures of Ginkgo from the Mediterranean Tertiary. Review of Palaeobotany and Palynology, 120, 1–15. Denk, T., Grímsson, F., & Kvaček, Z. (2005). The Miocene floras of Iceland and their significance for late Cainozoic North Atlantic biogeography. Botanical Journal of the Linnean Society, 149, 369–417. Denk, T., Grímsson, F., & Zetter, R. (2010). Episodic migration of oaks to Iceland: Evidence for a North Atlantic “land bridge” in the latest Miocene. American Journal of Botany, 97, 276–287. Flora of China Editorial Committee. (1999). Flora of China, Cycadaceae through Fagacaeae (Vol. 4). St. Louis: Missouri Botanical Garden Press. 453 pp. Flora of North America Editorial Committee. (1997). Flora of North America North of Mexico, Magnoliophyta: Magnoliidae and Hamamelidae (Vol. 3). New York: Oxford University Press. 616 pp. Friedrich, W. L. (1968). Tertiäre Pflanzen im Basalt von Island. Meddelelser fra Dansk Geologisk Førening, 18, 265–276. Friedrich, W. L., & Símonarson, L. A. (1982). Acer-Funde aus dem Neogene von Island und ihre stratigraphische Stellung. Palaeontographica B, 182, 151–166. Gregor, H.-J. (1986). Die Früchte und Samen aus der Oberen Süßwassermolasse von Achldorf bei Vilsbiburg (Niederbayern). Documenta naturae, 30, 49–59. Grímsson, F., & Denk, T. (2005). Fagus from the Miocene of Iceland: Systematics and biogeographical considerations. Review of Palaeobotany and Palynology, 134, 27–54. Grímsson, F., & Denk, T. (2007). Floristic turnover in Iceland from 15 to 6 Ma extracting biogeographical signals from fossil floral assemblages. Journal of Biogeography, 34, 1490–1504. Hably, L., & Marrón, M. (2007). The first macrofossil record of Ginkgo from the Iberian Peninsula. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen, 244, 65–70. Heer, O. (1859). Flora Tertiaria Helvetica – Die tertiäre Flora der Schweiz (Vol. 3). Winterthur: J. Wurster & Compagnie. 378 pp. Heer, O. (1868). Flora fossilis arctica 1. Die Fossile Flora der Polarländer enthaltend die in Nordgrönland, auf der Melville-Insel, im Banksland, am Mackenzie, in Island und in Spitzbergen entdeckten fossilen Pflanzen. Zürich: F. Schulthess. 192 pp. Jóhannesson, H., & Sæmundsson, K. (1989). Geological map of Iceland. 1:500 000: Bedrock geology (1st ed.). Reykjavík: Icelandic Museum of Natural History and Icelandic Geodetic Survey. Knobloch, E. (1986). Die Flora aus der Oberen Süßwassermolasse von Achldorf bei Vilsbiburg (Niederbayern). Documenta naturae, 30, 14–48. Kottek, M., Grieser, J., Beck, C., Rudolf, B., & Rubel, F. (2006). World map of the Köppen-Geiger climate classification updated. Meteorologische Zeitschrift, 15, 259–263. Kvaček, Z., & Sakala, J. (2006). Twig with attached leaves, fruits and seeds of Decodon (Lythraceae) from the Lower Miocene of northern Bohemia, and implications for the identification of detached leaves and seeds. Review of Palaeobotany and Palynology, 107, 201–222. Kvaček, Z., & Walther, H. (1988). Revision der mitteleuropäischen tertiären Fagaceen nach blattepidermalen Charakteristiken II. Teil – Castanopsis (D. Don) Spach, Trigonobalanus Forman, Trigonobalanopsis Kvaček & Walther. Feddes Repertorium, 99, 395–418. Kvaček, Z., Teodoridis, V., & Roiron, P. (in press). A forgotten Miocene mastixioid flora of Arjuzanx (Landes, SW France). Palaeontographica B. References 313 Landmælingar Íslands. (1994). Uppdráttur Íslands. Blað 33, Óspakseyri. Scale 1:100000. Leopold, E. B., & Liu, G. (1994). A long pollen sequence of Neogene age, Alaska Range. Quaternary International, 22(23), 103–140. Magallón, S., Crane, P. R., & Herendeen, P. S. (1999). Phylogenetic pattern, diversity, and diversification of eudicots. Annals of the Missouri Botanical Garden, 86, 297–372. Mai, H. D. (1995). Tertiäre Vegetationsgeschichte Europas. Jena: Gustav Fischer. 691 pp. Manchester, S. R. (1999). Biogeographical relationships of North American Tertiary floras. Annals of the Missouri Botanical Garden, 86, 472–522. Manum, S. (1962). Studies in the Tertiary flora of Spitsbergen, with notes on the Tertiary floras of Ellesmere Islands, Greenland, and Iceland. Norsk Polarinstitutt Skrifter, 125, 1–127. McDougall, I., Kristjansson, L., & Saemundsson, K. (1984). Magnetostratigraphy and geochronology of Northwest Iceland. Journal of Geophysical Research, 89, 7029–7060. Nixon, K. C., & Poole, J. M. (2003). Revision of the Mexican and Guatemalan species of Platanus (Platanaceae). Lundellia, 6, 103–137. Olavius, O. (1780). Oeconomisk Reise igiennem de nordvestlige, nordlige og nordostlige Kanter af Island, I-II. Kiøbenhavn: Gyldendal. 756 pp. Pflug, H. D. (1956). Sporen und Pollen von Tröllatunga (Island) und ihre Stellung zu den pollenstratigraphischen Bildern Mitteleuropas. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen, 102, 409–430. Royer, D. L., Hickey, L. J., & Wing, S. L. (2003). Ecological conservatism in the “living fossil” Ginkgo. Paleobiology, 29, 84–104. Schmitt, H. (1986). Bemerkungen zu einer Zelkova-Fruktifikation aus dem Achldorfer Pflanzenmergel. Documenta naturae, 30, 60–62. Símonarson, L. A. (1991). Hikkoría frá Tröllatungu. Náttúrufræðingurinn, 60, 144. Símonarson, L. A., Friedrich, W. L., & Imsland, P. (1975). Hraunafsteypur af trjám í íslenzkum tertíerlögum. Náttúrufræðingurinn, 44, 140–149. Tanai, T., & Suzuki, N. (1963). Miocene floras of southwestern Hokkaido, Japan. In The Tertiary Paleobotany Project (Ed.), Tertiary floras of Japan. Miocene floras (The collaborating association to commemorate the 80th anniversary of the geological survey of Japan, pp. 9–149). Tokyo: Geological Survey of Japan. Thompson, R. S., Anderson, K. H., & Bartlein, P. J. (1999). Atlas of relations between climatic parameters and distribution of important trees and shrubs in North America-Hardwoods. United States Geological Survey Professional Paper, 1650-B, 1–423. Thompson, R. S., Anderson, K. H., Bartlein, P. J., & Smith, S. A. (2000). Atlas of relations between climatic parameters and distribution of important trees and shrubs in North AmericaAdditional conifers, hardwoods, and monocots. United States Geological Survey Professional Paper, 1650-C, 1–386. Thoroddsen, Þ. (1896). Nogle iagttagelser over surtarbrandens geologiske forhold i det nordvestlige Island. Geologiska Föreningens i Stockholm Förhandlingar, 18, 114–154. Thoroddsen, Þ. (1906). Island: Grundriss der Geographie und Geologie. Gotha: Justus Perthes. 358 pp. Thoroddsen, Þ. (1914). Ferðabók II. Kaupmannahöfn: Hið íslenska fræðafélag. 293 pp. Thoroddsen, Þ. (1915). Ferðabók IV. Kaupmannahöfn: Hið íslenska fræðafélag. 356 pp. Tiffney, B. H. (1986). Evolution of seed dispersal syndromes according to the fossil record. In D. R. Murray (Ed.), Seed dispersal (pp. 274–305). Sydney: Academic. Tiffney, B. H. (2004). Vertebrate dispersal of seed plants through time. Annual Review of Ecology, Evolution and Systematics, 35, 1–29. Unger, H. J. (1986). Zur Geologie (Sedimentologie, Lithologie) des Obermiozäns von Achldorf / Niederbayern. Documenta naturae, 30, 1–13. Walther, H., & Zetter, R. (1993). Zur Entwicklung der paläogenen Fagaceae Mitteleuropas. Palaeontographica, B 230, 183–194. White, J. M., Ager, T. A., Adam, D. P., Leopold, E. B., Giu, G., Jetté, H., & Schweger, C. E. (1997). An 18 million year record of vegetation and climate change in northwestern Canada 314 6 The Early Late Miocene Floras (10 Ma) and Alaska: Tectonic and global climatic correlates. Palaeogeography, Palaeoclimatology, Palaeoecology, 130, 293–306. Windisch, P. (1886). Beiträge zur Kenntniss der Tertiärflora von Island. Zeitschrift für Naturwissenschaften, 4(5), 215–262. Winkler, G. G. (1863). Island: Der Bau seiner Gebirge und dessen geologische Bedeutung. München: Gummi. 303 pp. Wolfe, J. A., & Tanai, T. (1980). The Miocene Seldovia Point flora from the Kenai Group, Alaska. United States Geological Survey Professional Paper, 1105, 1–52. Zachos, J. C., Pagani, M., Sloan, L., Thomas, E., & Billups, K. (2001). Trends, rhythms, and aberrations in global climate 65 Ma to present. Science, 292, 686–693. Explanation of Plates Plate 6.1 1. Húsavíkurkleif and 2. Tröllatunga (Grýlufoss) in Steingrímsfjörður, northwestern Iceland, Tröllatunga-Gautshamar Formation (ca 10 Ma). 3. View of the Húsavíkurkleif outcrop, section composed of brownish to reddish iron-rich siltstones and sandstones, with lignite seams and volcanic tephra layers. 4. Thick pyroclastic pumice rich sedimentary rock unit characteristic for the Tröllatunga outcrops. 5. The iron-rich sedimentary rock unit at Húsavíkurkleif, fossils found here in concretions. 6. Close-up showing parts of lignified stems in the white pyroclastic unit found in the Tröllatunga region. 7. Fossil preserved in brownish to reddish iron-rich concretion from the Húsavíkurkleif outcrop. 8. Whorl of leaves (distal part of Rhododendron branch) preserved in the white pyroclastic unit of the Tröllatunga outcropsv Plate 6.2 1–3. Huperzia sp. 1. Spore in SEM, proximal polar view showing trilete tetrad mark. 2. Detail of spore surface. 3. Spore in LM, polar view. 4–6. Polypodiaceae gen. et spec. indet. 1. 4. Spore in SEM, proximal polar view showing monolete tetrad mark. 5. Detail of spore surface. 6. Spore in LM, polar view showing monolete tetrad mark. 7–9. Sphagnum sp. 7. Spore in SEM, distal polar view. 8. Detail of spore surface. 9. Spore in LM, polar view showing trilete tetrad mark. 10–12. Sphagnum sp. 10. Spore in SEM, proximal polar view showing trilete tetrad mark. 11. Detail of spore surface. 12. Spore in LM, polar view showing trilete tetrad mark Plate 6.3 1. Bryophyta fam. et gen. indet., acrocarpous moss with numerous stems (S 106487). 2. Detail of Fig. 1 showing two stems with spirally arranged leaves. 3, 5 and 7. Lycopodium sp. 3. Spore in SEM, distal polar view. 5. Spore in LM, polar view. 7. Detail of spore surface. 4 and 6. Lycopodium sp. 4. Spore in SEM, proximal polar view showing trilete tetrad mark. 6. Spore in LM, polar view. 8, 10 and 12. Lycopodium sp. 8. Detail of spore surface. 10. Spore in SEM, proximal polar view. 12. Spore in LM, polar view. 9, 11 and 13. Lycopodium sp. 9. Detail of spore surface. 11. Spore in SEM, proximal polar view showing trilete tetrad mark. 13. Spore in LM, polar view Plate 6.4 1–3. Huperzia sp. 1. Spore in SEM, distal polar view. 2. Detail of spore surface. 3. Spore in LM, proximal polar view showing trilete tetrad mark. 4–6. Huperzia sp. 4. Spore in SEM, equatorial view. 5. Detail of spore surface. 6. Spore in LM, oblique polar view. 7–9. Huperzia sp. 7. Spore in SEM, distal polar view. 8. Detail of spore surface. 9. Spore in LM, proximal polar view showing trilete tetrad mark. 10–12. Osmunda sp. 10. Spore in SEM, proximal polar view showing trilete tetrad mark. 11. Detail of spore surface. 12. Spore in LM, polar view Plate 6.5 1, 2 and 7. Osmunda sp. 1. Spore in SEM, proximal polar view showing trilete tetrad mark. 2. Detail of spore surface. 7. Spore in LM, polar view. 3, 4 and 8. Osmunda sp. 3. Spore in Explanation of Plates 315 SEM, distal polar view. 4. Detail of spore surface. 8. Spore in LM, proximal polar view showing trilete tetrad mark. 5 and 6. Osmunda sp. 5. Spore in SEM, oblique proximal polar view. 6. Detail of spore surface. 9 and 10. Osmunda sp. 9. Spore in SEM, proximal polar view showing trilete tetrad mark. 10. Detail of spore surface Plate 6.6 1. Osmunda parschlugiana, leaf with alternately arranged pinnae (S 106766). 2. Osmunda parschlugiana, lower part of pinna with a wide base (IMNH). 3. Detail of Fig. 1 showing venation and branching towards margin. 4. Osmunda parschlugiana, distal part of leaf with densely spaced small pinnae (IMNH). 5. Osmunda parschlugiana, large pinna with numerous secondary veins (IMNH). 6. Pteridophyta gen. et spec. indet 1., leaf fragment. 7. Detail of Fig. 6 showing pinnae. 8. Equisetum sp., nodules (IMNH 5547). 9. Equisetum sp., rhizome/stem part (IMNH) Plate 6.7 1 and 3. Polypodium sp. 1. Monolete spore in SEM, equatorial view. 2. Spore in LM, equatorial view. 3–5. Polypodiaceae gen. et spec. indet 1. 3. Spore in SEM, equatorial view. 4. Detail of spore surface. 5. Spore in LM, proximal polar view showing monolete tetrad mark. 6–8. Polypodiaceae gen. et spec. indet 3. 6. Monolete spore in SEM, equatorial view. 7. Detail of spore surface. 8. Spore in LM, equatorial view. 9–11. Polypodiaceae gen. et spec. indet 4. 9. Monolete spore in SEM, equatorial view. 10. Detail of spore surface. 11. Spore in LM, equatorial view. 12–14. Polypodiaceae gen. et spec. indet 5. 12. Monolete spore in SEM, equatorial view. 13. Detail of spore surface. 14. Spore in LM, equatorial view Plate 6.8 1–3. Ginkgo sp. 1. Pollen grain in SEM. 2. Detail of pollen grain surface. 3. Pollen grain in LM. 4. Larix sp., long shoot with short lateral spur shots. 5. Detail of Fig. 4 showing section through a spur shot. 6. Detail of Fig. 4 showing short spur shot. 7. Pseudotsuga sp., female cone. 8–10. Larix/Pseudotsuga sp. 8. Pollen grain in SEM. 9. Detail of pollen grain surface. 10. Pollen grain in LM Plate 6.9 1. Sequoia abietina (Brongn.) Knobl., shoot with leaves (IMNH). 2. Sequoia abietina (Brongn.) Knobl., shoot with leaves (IMNH). 3. Picea sp., long shoot with raised scars indicating fallen leaves (S 106739). 4. Detail of Fig. 3 showing raised scars. 5. Picea sp., needle like leaf with truncate base (IMNH 2832-04). 6. Picea sp., needle like leaf with truncate base (IMNH 259). 7. Picea sp., needle like leaf with acute apex (S 106487). 8. Picea sp., needle like leaf with truncate base (IMNH 1960-03) Plate 6.10 1–5. Picea sp. 1. Bisaccate pollen grain in SEM, equatorial view. 2 and 3. Bisaccate pollen grain in LM, equatorial view. 4. Detail of corpus. 5. Detail of saccus. 6. Picea sp., male catkins with Picea sp. pollen in situ (S106517A). 7. Detail of Fig. 6 showing widely spaced microsporophylls. 8. Picea sp. pollen grain from catkin in Fig. 6., pollen grain in LM, equatorial view. 9–12. Pinus sp. 1 (Diploxylon type). 9. Bisaccate pollen grain in SEM, equatorial view. 10. Detail of corpus. 11 and 12. Pollen grain in LM, oblique equatorial view Plate 6.11 1–3. Tsuga sp.1. 1. Monosaccate pollen grain in SEM. 2. Detail of pollen grain surface. 3. Pollen grain in LM. 4–6. Sciadopitys sp. 4. Pollen grain in SEM, proximal polar view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, distal polar view. 7, 9 and 10. Sciadopitys sp. 7. Pollen grain in SEM, proximal polar view. 9. Detail of pollen grain surface. 10. Pollen grain in LM, polar view. 8 and 11. Sciadopitys sp. 8. Pollen grain in SEM, distal polar view. 11. Pollen grain in LM, polar view Plate 6.12 1–4. Apiaceae gen. et spec. indet. 1. 1. Pollen grain in SEM, equatorial view. 2. Pollen grain in LM, equatorial view. 3. Detail of pollen grain surface around porus. 4. Detail of pollen grain surface in polar area. 5 and 6. Apiaceae gen. et spec. indet. 2. 5. Pollen grain in SEM, equatorial view. 6. Pollen grain in LM, equatorial view. 7–9. Apiaceae gen. et spec. indet. 3. 7. Pollen 316 6 The Early Late Miocene Floras (10 Ma) grain in SEM, equatorial view. 8. Pollen grain in LM, equatorial view. 9. Detail of pollen grain surface in polar area. 10–13. Apiaceae gen. et spec. indet. 4. 10. Pollen grain in SEM, equatorial view. 11. Pollen grain in LM, equatorial view. 12. Detail of pollen grain surface in polar area. 13. Detail of pollen grain surface around porus Plate 6.13 1–4. Artemisia sp. 1. 1. Pollen grain in SEM, polar view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, equatorial view. 4. Pollen grain in LM, polar view. 5–7. Artemisia sp. 2. 5. Pollen grain in SEM, equatorial view. 6. Detail of pollen grain surface. 7. Pollen grain in LM, equatorial view. 8–10. Artemisia sp. 2. 8. Pollen grain in SEM, equatorial view. 9. Detail of pollen grain surface. 10. Pollen grain in LM, polar view Plate 6.14 1–3. Asteraceae gen. et spec. indet. 1 (Liguliflorae). 1. Pollen grain in SEM, polar view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, polar view. 4–6. Asteraceae gen. et spec. indet. 2. 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, equatorial view. 7–9. Asteraceae gen. et spec. indet. 2. 7. Pollen grain in SEM, equatorial view. 8. Detail of pollen grain surface. 9. Pollen grain in LM, equatorial view. 10–12. Asteraceae gen. et spec. indet. 3. 10. Pollen grain in SEM, polar view. 11. Detail of pollen grain surface. 12. Pollen grain in LM, polar view Plate 6.15 1. Alnus cecropiifolia, large wide elliptic leaf (S 087416). 2. Detail of Fig. 1 showing teeth and marginal venation. 3. Alnus cecropiifolia, elliptic leaf with round base (IMNH 3179). 4. Alnus kefersteinii, female infructescence (S 106556). 5. Alnus kefersteinii, female infructescence (IMNH). 6. Alnus kefersteinii, female infructescence (IMNH) Plate 6.16 1–3. Alnus sp. 1. 1. Pollen grain in SEM, polar view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, polar view. 4–6. Alnus sp. 1. 4. Pollen grain in SEM, polar view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, polar view. 7–9. Alnus sp. 2. 7. Pollen grain SEM, polar view. 8. Detail of pollen grain surface. 9. Pollen grain LM, polar view. 10–12. Alnus sp. 3. 10. Pollen grain in SEM, polar view. 11. Detail of pollen grain surface. 12. Pollen grain in LM, polar view. 13–15. Alnus sp. 3. 13. Pollen grain in SEM, polar view. 14. Detail of pollen grain surface. 15. Pollen grain in LM, polar view Plate 6.17 1–3. Betula sp. 1. Pollen grain in SEM, polar view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, polar view. 4–6. Betula sp. 4. Pollen grain in SEM, polar view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, polar view. 7–9. Carpinus sp. 2. 7. Pollen grain in SEM, polar view. 8. Detail of pollen grain surface. 9. Pollen grain in LM, polar view. 10–12. Carpinus sp. 2. 10. Pollen grain in SEM, polar view. 11. Detail of pollen grain surface. 12. Pollen grain in LM, polar view. 13–15. Corylus sp. 13. Pollen grain in SEM, polar view. 14. Detail of pollen grain surface. 15. Pollen grain in LM, polar view Plate 6.18 1–3. aff. Calycanthaceae 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, equatorial view. 4–6. aff. Calycanthaceae 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grains surface. 6. Pollen grain in LM, equatorial view. 7–9. aff. Calycanthaceae 7. Pollen grain in SEM, equatorial view. 8. Detail of pollen grain surface. 9. Pollen grain in LM, equatorial view. 10–12. aff. Calycanthaceae 10. Pollen grain in SEM, equatorial view. 11. Detail of pollen grain surface. 12. Pollen grain in LM, equatorial view Plate 6.19 1–3. Lonicera sp. 1. 1. Pollen grain in SEM, polar view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, polar view. 4–6. Lonicera sp. 1. 4. Pollen grain in SEM, oblique equatorial view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, oblique view. 7, 8 and 12. Lonicera sp. 2. 7. Pollen grain in SEM, oblique view. 8. Detail of pollen grain surface. 12. Pollen Explanation of Plates 317 grain in LM. 9–11. Lonicera sp. 3. 9. Pollen in SEM, polar view. 10. Detail of pollen grain surface. 11. Pollen grain in LM, polar view Plate 6.20 1–3. Caryophyllaceae gen. et spec. indet. 1. 1. Pollen grain in SEM. 2. Detail of pollen grain surface. 3. Pollen grain in LM. 4–6. Caryophyllaceae gen. et spec. indet. 1. 4. Pollen grain in SEM. 5. Detail of pollen grain surface. 6. Pollen grain in LM. 7–9. Caryophyllaceae gen. et spec. indet. 1. 7. Pollen grain in SEM. 8. Detail of pollen grain surface. 9. Pollen grain in LM. 10–12. Caryophyllaceae gen. et spec. indet. 3. 10. Pollen grain in SEM. 11. Detail of pollen grain surface. 12. Pollen grain in LM Plate 6.21 1–4. Caryophyllaceae gen. et spec. indet. 2. 1. Pollen grain in SEM. 2. Detail of pollen grain surface showing porus. 3. Detail of pollen grain surface around porus. 4. Pollen grain in LM. 5–7. Thalictrum sp. 1. 5. Pollen grain in SEM. 6. Detail of pollen grain surface. 7. Pollen grain in LM. 8–10. Thalictrum sp.1. 8. Pollen grain in SEM. 9. Detail of pollen grain surface. 10. Pollen grain in LM Plate 6.22 1–3. Chenopodium sp. 1. Pollen grain in SEM. 2. Detail of pollen grain surface. 3. Pollen grain in LM. 4–6. Chenopodiaceae gen. et spec. indet 1. 4. Pollen grain in SEM. 5. Detail of pollen grain surface. 6. Pollen grain in LM. 7–9. Chenopodiaceae gen. et spec. indet. 2. 7. Pollen grain in SEM. 8. Detail of pollen grain surface. 9. Pollen grain in LM Plate 6.23 1. Cyperaceae gen. et spec. indet. A, leaf fragment (S 094580). 2. Arctostaphylos sp., small leaf (S 106768). 3. Detail of Fig. 3 showing secondary venation and teeth along margin. 4. Vaccinium sp., elliptic leaf (S 106624). 5. Vaccinium sp., elliptic leaf with dentate margin (S 106621). 6. Vaccinium sp., detail showing small teeth along margin (S 106759). 7. Vaccinium sp., detail showing secondary venation and teeth along margin (S 106624) Plate 6.24 1–3. Rhododendron aff. ponticum 1. Medium sized narrow elliptic leaf (S 087459). 2. Medium sized narrow elliptic leaf (S 106760). 3. Small narrow elliptic leaf (S 106740). 4–6. Rhododendron sp., bud scales Plate 6.25 1, 3 and 5. Ericaceae gen. et spec. indet. 1. 1. Tetrad in SEM. 3. Detail of tetrad surface. 5. Tetrad in LM. 2, 4 and 6. Ericaceae gen. et spec. indet. 1. 2. Tetrad in SEM. 4. Detail of tetrad surface. 6. Tetrad in LM Plate 6.26 1–4. Rhododendron sp. 2. 1. Tetrad in SEM. 2. Detail of tetrad surface close to apertures. 3. Detail of tetrad surface in mesocolpium. 4. Tetrad in LM. 5–8. Rhododendron sp. 2. 5. Tetrad in SEM. 6. Detail of tetrad surface. 7. Tetrad in LM. 8. Detail showing origin of viscin threads Plate 6.27 1–4. Fagus sp. 1. Pollen in SEM, equatorial view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, equatorial view. 4. Pollen grain in LM, polar view. 5–7. Trigonobalanopsis sp. 5. Pollen in SEM, equatorial view. 6. Detail of pollen grain surface. 7. Pollen grain in LM, equatorial view. 8–10. Trigonobalanopsis sp. 8. Pollen grain in SEM, equatorial view. 9. Detail of pollen grain surface. 10. Pollen grain in LM, oblique equatorial view Plate 6.28 1. Pterocarya sp., medium sized leaflet with asymmetric base (IMNH). 2. Cyclocarya sp., medium sized wide elliptic leaflet (S 106722 A). 3. Cyclocarya sp., counterpart to specimen on Fig. 2 (S 106722 B). 4. Cyclocarya sp., large elliptic leaflet (S 106525). 5. Detail of Fig. 4 showing secondary venation, looping and branching towards margin. 6. Detail of Fig. 4 showing teeth along margin 318 6 The Early Late Miocene Floras (10 Ma) Plate 6.29 1–3. Pterocarya sp. 1. Pollen grain in SEM, polar view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, polar view. 4–6. Pterocarya sp. 4. Pollen grain in SEM, polar view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, polar view. 7–10. Liliaceae gen. et spec. indet. 3. 7. Pollen grain in SEM, distal polar view. 8. Detail of pollen grain surface showing reticulate sculpturing. 9. Detail of pollen grain surface showing a more closed tectum. 10. Pollen grain in LM, distal polar view Plate 6.30 1–3. Liliaceae gen. et spec. indet. 2. 1. Pollen grain in SEM, proximal polar view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, polar view. 4–7. Liliaceae gen. et spec. indet. 3. 4. Pollen grain in SEM, oblique equatorial view. 5. Detail of pollen grain surface close to sulcus. 6. Pollen grain in LM, distal polar view showing sulcus. 7. Detail of pollen grain surface at proximal polar area Plate 6.31 1–3. Decodon sp. 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, equatorial view. 4–6. Decodon sp. 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, equatorial view. 7–9. Decodon sp. 7. Pollen grain SEM, equatorial view. 8. Detail of pollen grain surface. 9. Pollen grain in LM, equatorial view. 10–12. Decodon sp. 10. Pollen grain in SEM, equatorial view. 11. Detail of pollen grain surface. 12. Pollen grain in LM Plate 6.32 1. cf. Nuphar sp., part of large round leaf (S 106711). 2. Detail of Fig. 1 showing venation. 3–6. aff. Plantago lanceolata. 3. Pollen grain in SEM. 4. Detail of pollen grain surface. 5. Pollen grain in LM. 6–8. Platanus sp. 6. Pollen grain in SEM, equatorial view. 7. Detail of pollen grain surface. 8. Pollen grain in LM, equatorial view. 9–11. Rumex sp. 9. Pollen grain in SEM, polar view. 10. Detail of pollen grain surface. 11. Pollen grain in LM, equatorial view Plate 6.33 1. Phragmites sp., rhizomes (IMNH). 2. Phragmites sp., part of leaves (IMNH org 127). 3–5. Poaceae gen. et spec. indet. 1. 3. Pollen grain in SEM. 4. Detail of pollen grain surface. 5. Pollen grain in LM. 6–8. Poaceae gen. et spec. indet. 1. 6. Pollen grain in SEM. 7. Detail of pollen grain surface. 8. Pollen grain LM. 9–11. Anemone sp. 9. Pollen grain in SEM, equatorial view. 10. Detail of pollen grain surface. 11. Pollen grain in LM, equatorial view Plate 6.34 1–3. Ranunculaceae gen. et spec. indet 1. 1. Pollen grain in SEM, polar view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, polar view. 4–6. Ranunculaceae gen. et spec. indet 2. 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, equatorial view. 7–9. Ranunculaceae gen. et spec. indet 2. 7. Pollen grain in SEM, equatorial view. 8. Detail of pollen grain surface. 9. Pollen grain in LM, equatorial view. 10–12. Ranunuclus sp.1. 10. Pantocolpate pollen grain in SEM. 11. Detail of pollen grain surface. 12. Pollen grain in LM. 13–15. Polygonum sect. Aconogonon sp. 13. Pantoporate pollen grain in SEM. 14. Detail of pollen grain surface. 15. Pollen grain in LM Plate 6.35 1. Rosaceae gen. et spec. indet. type A, small elliptic leaf with a long petiole (S 106524). 2. Detail of Fig. 1 showing venation and teeth along margin. 3–6. Rosaceae gen. et spec. indet. 3. 3. Pollen grain in SEM, equatorial view. 4. Detail of pollen grain surface. 5. Pollen grain in LM, polar view. 6. Pollen grain in LM, equatorial view. 7–9. Rosaceae gen. et spec. indet. 3. 7. Pollen grain in SEM, equatorial view. 8. Detail of pollen grain surface. 9. Pollen grain in LM, equatorial view. 10–12. Rosaceae gen. et spec. indet. 3. 10. Pollen grain in SEM, polar view. 11. Detail of pollen grain surface. 12. Pollen grain in LM, polar view Plate 6.36 1–3. Rosaceae gen. et spec. indet. 4. 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, equatorial view. 4–7. Rosaceae gen. et spec. indet. 5. 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, Explanation of Plates 319 polar view. 7. Pollen grain LM, equatorial view. 8–11. Rosaceae gen. et spec. indet. 6. 8. Pollen grain in SEM, equatorial view. 9. Detail of pollen grain surface. 10. Pollen grain in LM, polar view. 11. Pollen grain in LM, equatorial view. 12–14. Rosaceae gen. et spec. indet. 7. 12. Pollen grain in SEM, equatorial view. 13. Detail of pollen grain surface. 14. Pollen grain in LM, equatorial view Plate 6.37 1–3. Rosaceae, unassigned pollen grain. 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, equatorial view. 4–6. Rosaceae, unassigned pollen grain. 4. Pollen grain in SEM, oblique equatorial view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, equatorial view. 7–9. Rosaceae, unassigned pollen grain. 7. Pollen grain in SEM, oblique polar view. 8. Detail of pollen grain surface. 9. Pollen grain in LM, oblique polar view. 10–12. Crataegus sp. 10. Pollen grain in SEM, equatorial view. 11. Detail of pollen grain surface. 12. Pollen grain in LM, equatorial view Plate 6.38 1–3. Rosaceae gen. et spec. indet. 8. 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, equatorial view. 4–6. Rosaceae gen. et spec. indet. 9. 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, equatorial view. 7–9. Sanguisorba sp. 7. Pollen grain in SEM, equatorial view. 8. Detail of pollen grain surface. 9. Pollen grain in LM, equatorial view. 10–12. Sanguisorba sp. 10. Pollen grain in SEM, polar view. 11. Detail of pollen grain surface. 12. Pollen grain in LM, polar view Plate 6.39 1. Salix gruberi, part of leaf (S 094633). 2–4. Salix sp. 2. 2. Pollen grain in SEM, equatorial view. 3. Detail of pollen grain surface. 4. Pollen grain in LM, equatorial view. 5–7. Salix sp. 3. 5. Pollen grain in SEM, equatorial view. 6. Detail of pollen grain surface. 7. Pollen grain in LM, equatorial view. 8–10. Salix sp. 3. 8. Pollen grain in SEM, equatorial view. 9. Detail of pollen grain surface. 10. Pollen grain in LM, equatorial view. 11–13. Salix sp. 3. 11. Pollen grain in SEM, equatorial view. 12. Detail of pollen grain surface. 13. Pollen grain in LM, equatorial view Plate 6.40 1. Acer askelssonii, part of large 7 lobed leaf (IMNH). 2. Acer askelssonii, small 3 lobed leaf (S 094385). 3. Acer askelssonii, part of large samara showing the pericarp, arrows pointing to attachment scar (S 106898). 4. Acer crenatifolium subsp. islandicum, medium sized 5 lobed leaf (S 087458). 5. Acer crenatifolium subsp. islandicum, small 3 lobed leaf (S 106774). 6. Acer crenatifolium subsp. islandicum, samara (S 106710). 7. Acer crenatifolium subsp. islandicum, samara with complete pericarp and wing (S 106717). 8. Acer crenatifolium subsp. islandicum, samara (S 106715). 9. Acer crenatifolium subsp. islandicum, attached samaras with a long pedicel (S 106580) Plate 6.41 1–3. Acer sp. 1. 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, equatorial view. 4–6. Acer sp. 3. 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, equatorial view. 7, 10 and 14. Acer sp. 4. 7. Pollen grain in SEM, equatorial view. 10. Detail of pollen grain surface. 14. Pollen grain in LM, equatorial view. 8, 11 and 12. Acer sp. 4. 8. Pollen grain in SEM, equatorial view. 11. Detail of pollen grain surface. 12. Pollen grain in LM, equatorial view. 9 and 13. Acer sp. 4. 9. Pollen grain in SEM, equatorial view. 13. Detail of pollen grain surface Plate 6.42 1. Smilax sp., upper half of leaf (S 106746). 2. Detail of Fig. 1 showing venation and entire margin. 3. Smilax sp., apical part of leaf (S 106749). 4. Dicotylophyllum sp. C, small elliptic leaf with spinose teeth (S 106780). 5. Detail of Fig. 4 showing teeth along margin. 6. Dicotylophyllum sp. B, fragment of leaf (S 106673). 7. Detail of Fig. 6 showing glandular teeth Plate 6.43 1–3. Tilia sp. 1. Pollen grain in SEM, polar view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, polar view. 4–6. Ulmus sp. 4. Pollen in SEM, polar view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, polar view. 7–9. Parthenocissus sp. 7. Pollen grain in SEM, 320 6 The Early Late Miocene Floras (10 Ma) equatorial view. 8. Detail of pollen grain surface. 9. Pollen grain in LM, equatorial view. 10–12. Parthenocissus sp. 10. Pollen grain in SEM, equatorial view. 11. Detail of pollen grain surface. 12. Pollen grain in LM, equatorial view Plate 6.44 1–3. Pollen type 8. 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, equatorial view. 4–6. Pollen type 9. 4. Pollen grain in SEM. 5. Detail of pollen grain surface. 6. Pollen grain in LM, equatorial view. 7–9. Pollen type 10. 7. Pollen grain in SEM, equatorial view. 8. Detail of pollen grain surface. 9. Pollen grain LM, equatorial view. 10–13. Pollen type 11. 10. Pollen grain in SEM, oblique equatorial view. 11. Detail of pollen grain surface. 12. Pollen grain in LM, polar view. 13. Pollen grain in equatorial view Plate 6.45 1–3. Pollen type 12. 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, equatorial view. 4–6. Pollen type 13. 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, equatorial view. 7–9. Pollen type 13. 7. Pollen grain in SEM, equatorial view. 8. Detail of pollen grain surface. 9. Pollen grain in LM, equatorial view. 10–12. Pollen type 14. 10. Pollen grain in SEM, equatorial view. 11. Detail of pollen grain surface. 12. Pollen grain in LM, equatorial view Plate 6.46 1–3. Pollen type 15. 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, equatorial view. 4–6. Pollen type 16. 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, equatorial view. 7–9. Pollen type 17. 7. Pollen grain in SEM. 8. Detail of pollen grain surface. 9. Pollen grain in LM. 10–12. Pollen type 18. 10. Pollen grain in SEM, oblique polar view. 11. Detail of pollen grain surface. 12. Pollen grain in LM, equatorial view Plate 6.47 1–3. Pollen type 19. 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, equatorial view. 4–6. Pollen type 20. 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, equatorial view Plates Plate 6.1 322 6 The Early Late Miocene Floras (10 Ma) Plate 6.2 Plates 323 Plate 6.3 324 6 The Early Late Miocene Floras (10 Ma) Plate 6.4 Plates 325 Plate 6.5 326 6 The Early Late Miocene Floras (10 Ma) Plate 6.6 Plates 327 Plate 6.7 328 6 The Early Late Miocene Floras (10 Ma) Plate 6.8 Plates 329 Plate 6.9 330 6 The Early Late Miocene Floras (10 Ma) Plate 6.10 Plates 331 Plate 6.11 332 6 The Early Late Miocene Floras (10 Ma) Plate 6.12 Plates 333 Plate 6.13 334 6 The Early Late Miocene Floras (10 Ma) Plate 6.14 Plates 335 Plate 6.15 336 6 The Early Late Miocene Floras (10 Ma) Plate 6.16 Plates 337 Plate 6.17 338 6 The Early Late Miocene Floras (10 Ma) Plate 6.18 Plates 339 Plate 6.19 340 6 The Early Late Miocene Floras (10 Ma) Plate 6.20 Plates 341 Plate 6.21 342 6 The Early Late Miocene Floras (10 Ma) Plate 6.22 Plates 343 Plate 6.23 344 6 The Early Late Miocene Floras (10 Ma) Plate 6.24 Plates 345 Plate 6.25 346 6 The Early Late Miocene Floras (10 Ma) Plate 6.26 Plates 347 Plate 6.27 348 6 The Early Late Miocene Floras (10 Ma) Plate 6.28 Plates 349 Plate 6.29 350 6 The Early Late Miocene Floras (10 Ma) Plate 6.30 Plates 351 Plate 6.31 352 6 The Early Late Miocene Floras (10 Ma) Plate 6.32 Plates 353 Plate 6.33 354 6 The Early Late Miocene Floras (10 Ma) Plate 6.34 Plates 355 Plate 6.35 356 6 The Early Late Miocene Floras (10 Ma) Plate 6.36 Plates 357 Plate 6.37 358 6 The Early Late Miocene Floras (10 Ma) Plate 6.38 Plates 359 Plate 6.39 360 6 The Early Late Miocene Floras (10 Ma) Plate 6.40 Plates 361 Plate 6.41 362 6 The Early Late Miocene Floras (10 Ma) Plate 6.42 Plates 363 Plate 6.43 364 6 The Early Late Miocene Floras (10 Ma) Plate 6.44 Plates 365 Plate 6.45 366 6 The Early Late Miocene Floras (10 Ma) Plate 6.46 Plates 367 Plate 6.47