The Archaic Floras more

Chapter 4 The Archaic Floras Abstract The oldest plant fossils currently known from Iceland are ca 15 Ma, their deposition coinciding with the Mid-Miocene Climatic Optimum. At this time, forests in Iceland were dominated by mixed broadleaved deciduous and coniferous taxa with a few broadleaved evergreen genera such as Rhododendron and Ilex. Lowland forests were dominated by Glyptostrobus. Questions about the colonization history of Iceland or proto-Iceland are of particular interest since not much is known about the availability of effective land bridges allowing for colonization from Europe and/or North America at that time. In addition to geological data, in this chapter we use two lines of biological evidence to speculate about the early colonization of Iceland. First, we will examine the biogeographic patterns of key taxa such as Cryptomeria, Rhododendron ponticum-type, and Fagus friedrichii. Then we look at dispersal modes found in early colonizers of Iceland. Dispersal modes of at least some taxa indicate that Iceland was connected to the adjacent continents at the time of colonization. However, it cannot be determined when exactly this early colonization happened. The taxa recorded in the oldest sedimentary rocks in Iceland may have had different origins, either representing elements that were already present in the region since the Palaeogene or colonizing proto-Iceland from North America/Greenland and/or Europe later in the Neogene. 4.1 Introduction The oldest plant-bearing sediments of Iceland belong to the Selárdalur-Botn Formation and are ca 15 Ma (Langhian, early Middle Miocene; Moorbath et al. 1968; Kristjánsson et al. 1975, 2003; McDougall et al. 1984; Hardarson et al. 1997). Traditionally, much less attention has been paid to these sedimentary rocks than to the younger, ca 12 Ma, Brjánslækur-Seljá Formation (Heer 1859, 1868; Mai 1995; see Chap. 5). This is probably due to the much more fragmentary preservation of macrofossils from the Selárdalur-Botn Formation and the remoteness of exposures belonging to this formation. Moreover, the macrofossil record of this formation is scanty compared to the greatly richer flora from Brjánslækur. The Icelandic geologist Jóhannes Áskelsson (1946, 1956, 1957) was the first to carry out research T. Denk et al., Late Cainozoic Floras of Iceland, Topics in Geobiology 35, DOI 10.1007/978-94-007-0372-8_4, © Springer Science+Business Media B.V. 2011 173 174 4 The Archaic Floras on the Selárdalur flora. He compared Icelandic macrofossils to “Miocene” plant fossils from Arctic areas published by Oswald Heer in the nineteenth century. Heer had considered Arctic floras from Greenland, Spitsbergen, and Iceland to be of Miocene age (Heer 1868–1883), but later studies showed that Cainozoic sediments from Greenland and Spitsbergen were much older (Palaeocene to Oligocene; Ravn 1922; Koch 1963; Dallmann 1999). For this reason, Áskelsson (1946) introduced species such as Vitis olriki Heer to the flora of Iceland. The species had earlier been described from Greenland (Heer 1868). According to Budantsev (1992), this species is of uncertain taxonomic affinity, and was a typical element of boreal temperate forests in the latest Cretaceous and early Cainozoic. In the present account, leaves from Iceland that had previously been assigned to ‘Vitis’, are identified as Tilia, which is further supported by palynological evidence. A more comprehensive account on the early Middle Miocene floras from Iceland has been provided by Akhmetiev et al. (1978), covering both macrofossils and palynological evidence using light microscopy. More recently, Grímsson and Denk (2005) and Grímsson et al. (2007) undertook a revision of macrofossils from the ca 15 Ma plant-bearing formation. This revision resulted in the recognition of several genera that had previously been unknown from the oldest sediments, such as Aesculus, Cercidiphyllum, Platanus, Sequoia, Tilia, and Ulmus. Although the Selárdalur and Botn macrofloras represent both zonal and azonal vegetation, the number of species recovered remained noticeably low compared to the younger Brjánslækur-Seljá (12 Ma, see Chap. 5) and Gautshamar-Tröllatunga Formations (10 Ma, see Chap. 6). For the present study, the palynological content of the sediments from the Botn locality was studied using both light and scanning electron microscopy resulting in a more complete picture of the Langhian floras of Iceland. In this chapter we use evidence from both the macro- and microfossil record to discuss various scenarios of the early migration of plants to Iceland from either North America/Greenland or Europe. Moreover the Langhian floras of Iceland are briefly compared to coeval mid and high latitude floras across the northern hemisphere. 4.2 Geological Setting and Taphonomy The Selárdalur-Botn Formation (15 Ma; Hardarson et al. 1997; Kristjansson et al. 2003) is exposed at the margins of the Northwest Peninsula (Fig. 4.1a, b). In the Selárdalur valley, macrofossils are found high up on Mount Þórishlíðarfjall (Fig. 4.1c; Plate 4.1). The fossil-rich sediments are ca 20 m thick and characterized by fine- to coarse-grained tuffaceous sedimentary rocks of pyroclastic origin. Generally, basaltic tuffs are most prominent, but some units contain a conspicuously high amount of white and yellowish pumice fragments. Sandstones are present in the lower to middle parts, and conglomerates in the upper parts. The sedimentary rocks and their structure indicate accumulation at moderate to high elevation (absence of fine-grained lake and river sediments) in some kind of small basin close to an active volcano. Plant remains lie both parallel to the lamination 4.2 Geological Setting and Taphonomy 175 Fig. 4.1 Map showing fossiliferous localities of the 15 Ma formation. (a) bedrock geology (see Fig. 1.10 for explanation), (b) extension of sedimentary rock formation, (c) Selárdalur locality, (d) Botn locality (Geological background modified after Jóhannesson and Sæmundsson 1989; altitudinal lines from Landmælingar Íslands 1990a, 1990b). Scale bar in kilometres and oblique to it, and many of the fossils are folded. The orientation of the plant fossils apparently reflects transport within the sedimentary material following a pyroclastic eruption. This eruption may have swept over the trees growing in and 176 4 The Archaic Floras Fig. 4.1 (continued) around the sedimentary basin, entraining leaves in the flow. The absence of plants producing delicate leaves in the sediments and the charcoalified skeleton of the leaf venation in most leaf remains indicate that this happened under high temperature. In the Botnsdalur valley at the base of Súgandafjörður (Fig. 4.1d; Plate 4.1), plant fossils are found close to the old lignite mine known as Botn mine or Botn locality. At the Botn locality sedimentary rocks are considerably thinner than in Selárdalur and are interpreted to reflect a lowland sedimentary environment with high groundwater level. The sediments are around 4 m thick and composed mainly of lignites with intercalated siltstones and ash layers. These sediments and their structure indicate deposition in a floodplain-dominated area with vast rivers and swamps, where organic material accumulated due to anoxic conditions. Leaves and fruits are preserved as compressions. 4.3 Floras, Vegetation, and Palaeoenvironments A total of 35 taxa are recognized from the Selárdalur-Botn Formation (Table 4.1; Plates 4.2–4.20). The vast majority belong to woody angiosperms (21 taxa) and conifers (8 taxa). Lianas, herbaceous angiosperms, and ferns make up only a small fraction of the total flora (5 taxa, Fig. 4.2). In general, fewer taxa are represented by macrofossils than by pollen (11 versus 32). While pollen data give a more generalized picture of the floral content, environmental differences are 4.3 Floras, Vegetation, and Palaeoenvironments Table 4.1 Taxa recorded for the 15 Ma floras of Iceland Selárdalur-Botn Formation Taxa Pollen Leaves Polypodiaceae Polypodium sp. + Polypodiaceae gen. et spec. indet.1 + Cupressaceae s.1. Cupressaceae gen. et spec. indet. 1 + (Cryptomeria sp.) Glyptostrobus europaeus + + L Cupressaceae gen. et spec. indet. 3 + (Juniperus sp.) Sequoia abietina + +L Pinaceae Cathaya sp. + ?Picea sp. + Pinus sp. 1 (Diploxylon type) + Tsuga sp. 1 + Aquifoliaceae Ilex sp. 1 + Betulaceae Alnus sp. 1 + Betula sp. 1 + Carpinus sp. 1 + Caprifoliaceae Lonicera sp. + Viburnum sp. + Cercidiphyllaceae Cercidiphyllum sp. + + Ericaceae cf. Rhododendron sp. + Rhododendron sp. 1 + Fagaceae Fagus friedrichii + + Juglandaceae Pterocarya sp. + Liliaceae Liliaceae gen. et spec. indet. 1 + Magnoliaceae cf. Magnolia sp. + Platanaceae Platanus leucophylla + + Rosaceae Rosaceae gen et. spec. indet. 1 + Rosaceae gen et. spec. indet. 2 + Rosaceae gen et. spec. indet. 3 + Sanguisorba sp. + 177 RP Cuticle DM 1a 1a 2a +A + + 2a 1b 2a 2a 2a 2a 2a 1b 1a, 2a 1a 2a 1b 1b 2a la, ?2a la, ?2a +D 2b, 3 2a 2a 1b 2a 1b 1b 1b 1b, 2a (continued) 178 Table 4.1 (continued) Selárdalur-Botn Formation Taxa 4 The Archaic Floras Pollen Leaves RP Cuticle DM Salicaceae Salix sp. 1 + 1a Sapindaceae Acer sp. 1 + 2a Acer sp. 2 + 2a Aesculus sp. + 2b, 3 Tiliaceae Tilia selardalense + + 1b, 2a Trochodendraceae Tetracentron atlanticum + 2a Ulmaceae Ulmus sp. MT1 + + 2a Vitaceae Parthenocissus sp. + 1b Incertae sedis – Magnoliophyta Pollen type 1 + ? 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, 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 Fig. 4.2 Distribution of life forms and higher taxa among the plants from the 15 Ma formation. Height of columns indicates number of taxa 4.3 Floras, Vegetation, and Palaeoenvironments 179 well reflected by macrofossils from volcanic sedimentary rocks at higher elevations (Selárdalur) and from lowland alluvial plains (Botn). The former are characterized by zonal elements and dominated by Fagus, whereas the latter are dominated by riparian elements inhabiting swamps and hammocks (e.g. Glyptostrobus). The most characteristic feature of the Selárdalur flora is the dominance of Fagus (>90% of the macrofossils). Other taxa include Tilia and Aesculus. The absence of azonal elements that are typically confined to lake and river environments, such as Salix, Alnus, and Glyptostrobus in the volcanic-pyroclastic sediments of Selárdalur points to the allochthonous or zonal character of this flora as opposed to the coeval Botn flora preserved in lignitic sediments. So far, only few macrofossil taxa have been recorded for the Botn flora. Of these, the most common ones are Glyptostrobus and Sequoia, which are represented by vegetative and fruiting twigs, whereas Fagus here is represented mainly by cupules and nuts, and only very few fragmentary leaves. The composition of the Botn macroflora and the sedimentary environment indicate a typical lowland flora of autochthonous origin. This lowland type of vegetation is likely to have merged into upland forests similar to the ones from Selárdalur. The combined macrofossil and palynological data allow a more differentiated reconstruction of the early Middle Miocene vegetation types and environments. Six main vegetation types can be distinguished (Table 4.2, Fig. 4.3). Azonal riparian vegetation was represented by elements from backswamp and natural levée forests. Backswamps are regularly flooded areas that are rather species poor. Typical elements of these forests were Glyptostrobus, Pterocarya, Alnus, and Salix, possibly intertwined with climbing Parthenocissus and forming thickets in some places (Fig. 4.4). Natural levées flanking rivers and hammocks in the floodplains are slightly more elevated areas that are only rarely exposed to inundation. Levées and hammocks were most likely inhabited by deciduous and evergreen angiosperms and lianas, such as Acer, Aesculus, Cercidiphyllum, Fraxinus, Platanus, Ilex, and Parthenocissus. Moving from the lowland riparian forests to the well-drained upland forests, the number of species increased considerably. Foothill forests may have gradually changed into montane forests (Fig. 4.5); here and there ravines with a humid micro-climate and deep soils, as well as rocky outcrops with poor soils would have occurred. Upland forests were mixed broadleaved deciduous (and evergreen) and conifer forests. In the foothills Sequoia, Tsuga, and various deciduous angiosperms (Acer spp., Carpinus) with an admixture of evergreen species (Ilex, possibly Magnolia) thrived. Higher up, montane forests were co-dominated by Fagus, Aesculus, Tilia, and Ulmus as well as conifers such as Picea, Tsuga, and Cryptomeria. Ilex and Rhododendron would have formed the understorey (Fig. 4.5). Ravine forests were probably composed of shade tolerant evergreen species (Ilex, Rhododendron) and rare elements such as Cathaya. Finally, rocky outcrop forests might have developed on poor substrates as patches within the richer upland forests but possibly also above the closed upland forests. These forests would have supplied species such as Pinus and the herbaceous Sanguisorba. Table 4.2 Vegetation types and their components during the mid-Miocene of Iceland. The palaeoecology of fossil species is reconstructed from their sedimentological context and ecology of modern analogues Vegetation types 15 Ma Backswamp forests Foothill forests Montane forests Ravine forests Polypodium sp. 1 Polypodium sp. 1 Polypodium sp. 1 Polypodium sp. 1 Polypodiaceae gen. et spec. indet. 1 Polypodiaceae gen. et spec. indet. 1 Polypodiaceae gen. et spec. indet. 1 Polypodiaceae gen. et spec. indet. 1 Glyptostrobus europaeus ?Picea sp. Cryptomeria sp. Cathaya sp. Alnus sp. 1 Sequoia abietina Juniperus sp. Aesculus sp. Parthenocissus sp. Tsuga sp. ?Picea sp. Ilex sp. Pterocarya sp. Aesculus sp. Pinus sp. 1 Acer sp. 1 Salix sp. 1 Ilex sp. Tsuga sp. Fagus friedrichii Acer sp. 1 Aesculus sp. Rhododendron sp. Acer sp. 2 Acer sp. 1 Tilia selardalense Levée forests Polypodium sp. 1 Alnus sp. 1 Cercidiphyllum sp. Ulmus sp. Polypodiaceae gen. et spec. indet. 1 Betula sp. 1 Fagus friedrichii Aesculus sp. Carpinus sp. 1 Rhododendron sp. Rocky outcrop forests Ilex sp. Cercidiphyllum sp. Rosaceae gen et. spec. indet. 1 Polypodium sp. 1 Acer sp. 2 Fagus friedrichii Rosaceae gen et. spec. indet. 2 Polypodiaceae gen. et spec. indet. 1 Alnus sp. 1 Magnolia sp. Rosaceae gen et. spec. indet. 3 Juniperus sp. Betula sp. 1 Parthenocissus sp. Tetracentron atlanticum Pinus sp. 1 Carpinus sp. 1 Platanus leucophylla Tilia selardalense Tsuga sp. Cercidiphyllum sp. Rhododendron sp. Ulmus sp. Cercidiphyllum sp. Magnolia sp. Rosaceae gen et. spec. indet. 1 Viburnum sp. Sanguisorba sp. Parthenocissus sp. Rosaceae gen et. spec. indet. 2 Tetracentron atlanticum Platanus leucophylla Rosaceae gen et. spec. indet. 3 Viburnum sp. Pterocarya sp. Salix sp. 1 Salix sp. 1 Tetracentron atlanticum Ulmus sp. Tilia selardalense Ulmus sp. Viburnum sp. zonAL VeGeTATIon AzonAL VeGeTATIon 4.3 Floras, Vegetation, and Palaeoenvironments 181 Fig. 4.3 Schematic block diagram showing palaeo-landscape and vegetation types for the early Middle Miocene of Iceland. See Table 4.2 for species composition of vegetation types Fig. 4.4 Schematic transect of a backswamp and levée forest 182 4 The Archaic Floras Fig. 4.5 Schematic transect of a montane forest 4.4 ecological and Climatic Requirements of Modern Analogues Several of the taxa typical of the Selárdalur-Botn formation have modern analogues that are confined to warm, humid temperate forests of North America and Eastern Asia (see Chap. 13, Appendix 13.1) and, in some cases, have very restricted distribution ranges at present. Some conifer species of the Selárdalur-Botn Formation belong to genera that are at present monotypic. Cathaya (Pinaceae) has a narrow distribution range in south Central China (Flora of China Editorial Committee 1999). The only living species, Cathaya argyrophylla Chun & Kuang grows in humid mountain areas on open slopes and ridges, at altitudes from 900 to 1,900 m a. s. l. It is part of evergreen broadleaved or mixed evergreen and deciduous broadleaved forests (Ying et al. 1983) thriving in a humid warm temperate climate (Cfa climate; Köppen and Geiger 1928; Köppen 1936; Kottek et al. 2006) with mean annual temperatures (MAT) of 9.3–18.6°C. The monotypic Glyptostrobus is an element of the lowlands of southeastern China growing close to or at sea level in river deltas or other flooded areas (Flora of China Editorial Committee 1999) at an MAT of 14.5–26.6°C. Glyptostrobus pensilis (Staunton ex D. Don) K. Koch occurs in humid warm temperate climates [warmest month mean temperature (WMMT) >22°C], mostly with dry winter months (Cwa climate sensu Köppen) but occasionally (southeastern Sichuan) with no dry season (Cfa climate). Sequoia constitutes coastal redwood forests in northern California and southern Oregon mainly below 300 m a. s. l. but occasionally reaching up to 1,000 m a. s. l. 4.4 Ecological and Climatic Requirements of Modern Analogues 183 (Flora of North America Editorial Committee 1993). Although its only modern representative Sequoia sempervirens (D. Don) Endl. is growing under a distinct Mediterranean macroclimate (Csa climate sensu Köppen) with winter rain and dry summer months, the actual climate resembles more a humid warm temperate Cfa/b climate because fog is acting as the main water source during the dry summer months (Dawson 1998). MAT in redwood forests ranges from 9.4°C to 15.3°C (Thompson et al. 1999a). Among angiosperms, Cercidiphyllum is represented today by two species in China and Japan. Cercidiphyllum japonicum Sieb. and Zucc. is part of mixed mesophytic forests and deciduous broadleaved forests, often along streams and at forest margins, in northern parts of southeast China and in Japan. It occurs between 600 and 2,700 m a. s. l. with MAT between 2.6°C and 15.9°C. Cercidiphyllum magnificum (Nakai) Nakai is endemic to central and northern Honshu, Japan, growing in deciduous forests along streams (Iwatsuki et al. 2006) between 500 and 1,500 m a. s. l. (Ohwi 1965). The species thrives at MAT 4.6–11.6°C. Both species are growing under a Cfa/b climate. Fagus consists of ten modern species in humid temperate areas of the northern hemisphere (Shen 1992; Denk 2003; Denk et al. 2005). Fagus friedrichii Grímsson & Denk belongs to an extinct Miocene lineage of Fagus extending from Alaska to Iceland (Grímsson and Denk 2005) and has been compared by the same authors to the modern North American F. grandifolia Ehrh. and the Japanese F. crenata Engl. A recent re-evaluation of this fossil species showed that it is most closely related among all modern and extinct species to Fagus washoensis LaMotte and F. idahoensis Axelrod & Chaney from the Miocene of western North America (Denk and Grimm 2009). Of the modern species comparable to Fagus friedrichii, Fagus crenata occurs from 5 to 1,500 (2,100) m a. s. l. At its northern distribution limit it forms forests close to sea level, while it covers a wide vertical range in its southern range (Shen 1992). It forms part of mixed broadleaved deciduous and conifer forests under a Cfa/b (to Dfa/b) climate, MAT 3–13°C (Peters 1997). Fagus grandifolia has a wide distribution in North America ranging from northern Florida to southern Canada and with a disjunct area in Mexico (Shen 1992). The American beech occurs in mixed woods, deciduous forests and mixed broadleaved and conifer forests ranging from sea level to 1,000 m a. s. l. (Flora of North America Editorial Committee 1997). It thrives in humid warm-temperate climates (Cfa/b to Dfa/b climate) with MAT 4–21°C (Peters 1997). Platanus is a small northern hemispheric genus with seven species (Nixon and Poole 2003). The fossil species from Iceland compares well with the North American P. occidentalis L. Platanus occidentalis covers a range from eastern Canada to Texas and northern Mexico. It is commonly found in alluvial forests along streams and lakes, sometimes in ravines and on uplands, stretching from sea level to about 1,000 m a. s. l. (Flora of North America Editorial Committee 1997). While the species grows mainly under a humid Cfa climate, with a MAT ranging from 5.4°C to 21.1°C (Thompson et al. 1999b), it enters a small zone of dry steppe climates (BSk climate sensu Köppen) in its southwestern range. Here, it does not occur as part of extensive forests but is confined to riparian communities in depressed river valleys and moist ravines. 184 4 The Archaic Floras Fig. 4.6 Climate diagrams for modern Iceland, and for climate stations resembling the climatic conditions inferred for the mid-Miocene of Iceland (Climate diagrams from Lieth et al. 1999). 1. Vestmannaeyjar, Cfc climate. 2. Philadelphia, Cfa climate. 3. Wajima, Cfa climate. 4. Rize, Cfa climate (Climate types according to Köppen, cf. Kottek et al. 2006) 4.5 Taxonomic Affinities and Origin of the Early Icelandic Floras 185 Except for some few taxa that occur in a wide range of climatic types, e.g. Juniperus sp., most of the taxa recorded for the ca 15 Ma formation are typical components of forests thriving under a humid warm temperate climate without any dry season (Cfa including Submediterranean variants of Cfb climates). Cfa climates are currently found in the (south)eastern United States (roughly corresponding to the “Eastern Deciduous Forests” of North America; Braun 1950) and montane forests of eastern Mexico (Miranda and Sharp 1950). In western Eurasia, Cfa climates are restricted to southern Europe, the Balkans, and the areas along the eastern Black Sea (Euxinian forests) and southern Caspian Sea (Hyrcanian forests; Meusel et al. 1965; Denk 1998; Denk et al. 2001). In East Asia Cfa climates are found in southeast China and Japan (mixed mesophytic forests and mixed broadleaved deciduous and evergreen forests; Wang 1961; Wolfe 1979). Although modern analogues of several taxa co-existing in Iceland ca 15 Ma currently display distribution ranges that do not overlap (for example, Glyptostrobus and Sequoia), they share a number of ecological and climatic features. Overall, they suggest that the Icelandic forests flourished under humid warm temperate climates (Cfa to Cfb climate). The minimal temperature requirements (MAT) of the taxa encountered in the ca 15 Ma floras are between 8°C and 12°C for upland environments and up to ca 15°C for lowland riparian elements such as Glyptostrobus. The position of Iceland in the North Atlantic would suggest that rainfall was evenly distributed over the year as it is today (fully humid Cfc climate in coastal lowlands; Kottek et al. 2006). Climatic diagrams probably matching the conditions for Iceland ca 15 Ma are shown in Fig. 4.6. 4.5 Taxonomic Affinities and origin of the early Icelandic Floras Many of the species encountered in the Middle Miocene of Iceland belong to genera that had a wide northern hemispheric distribution during that time; they could have reached Iceland either from North America or Eurasia. Examples include Cathaya (Liu and Basinger 2000; Saito et al. 2000; Hofmann et al. 2002), Glyptostrobus (Mai 1995; Budantsev 1997; Manchester 1999), Sequoia (Knobloch 1969; Meyer and Manchester 1997), Cercidiphyllum (La Motte 1936; Ferguson 1971; Shilin 1974; Ozaki 1991; Kovar-Eder et al. 2004). More detailed biogeographical analyses of these genera will depend on morphological studies evaluating transcontinental taxonomic relationships with higher taxonomic and stratigraphic resolution. By contrast, a small number of the genera are believed to have had a narrower geographic distribution in the northern hemisphere, and hence provide more information regarding the migration routes to Iceland. Cryptomeria has a fossil record that dates back to the Paleocene in Europe (Mai 1995). Unambiguous macrofossils are not older than Miocene (Kilpper 1968; Boulter 1969; Boulter and Chaloner 1970; Dolezych and Schneider 2007). The genus is entirely absent from the fossil record of North America (Manchester 1999). In view of the fossil distribution and the present 186 4 The Archaic Floras range of the genus (endemic with a single species in Japan), Cryptomeria is a strict Eurasian element and must have migrated to Iceland from continental Europe. Another interesting finding is that Rhododendron pollen recovered from the Langhian sediments of Iceland is indistinguishable from modern pollen of the western Eurasian species R. ponticum (Plate 4.11). The modern sister species of R. ponticum, the eastern North American R. maximum, is morphologically very similar to the Eurasian species but has a very distinct pattern of pollen tectum (Denk et al. unpublished data). This may indicate that Rhododendron migrated to Iceland from Europe during or before the early Middle Miocene. Fagus friedrichii represents an extinct lineage within the genus Fagus (Grímsson and Denk 2005; Plate 4.12) and the fossil record suggests that it had a disjunct distribution between Alaska and Iceland during the Miocene. Foliage resembling F. friedrichii has never been reported from European sediments (Denk 2004; Grímsson and Denk 2005). Further, a recent re-evaluation of F. friedrichii showed that it is most closely related among all modern and extinct species to Fagus washoensis and F. idahoensis from the Miocene of western North America (Denk and Grimm 2009). The latter two fossil species should perhaps be treated as two morphotypes of a single species (Chaney and Axelrod 1959). This suggests that Fagus friedrichii or its ancestors migrated to Iceland from North America via Greenland and is in agreement with the palynological record of Fagus in eastern and Arctic North America during the Early and Middle Miocene (see below Sect. 4.6). Recently, pollen, foliage, and fruits belonging to Tetracentron have been reported from Iceland (Grímsson et al. 2008). This finding is surprising because previously the genus was known only from East Asia and western North America (Suzuki 1967; Ozaki 1987; Chelebaeva and Shancer 1988; Manchester and Chen 2006; Pigg et al. 2007). The genus comprises a single living species, T. sinense Oliv., that occurs from central and southern China to northeastern India. The presence of Tetracentron in the Miocene of Iceland suggests that the biogeographic history of the genus is much more complex than previously thought. Tetracentron has very small pollen that is hard to discern in LM. A screening of European Neogene sediments for the genus using scanning electron microscopy (SEM) did not yield any Tetracentron pollen (Grímsson et al. 2008). Although more SEM studies are needed, this may indicate a migration to Iceland via Canada and Greenland similar to the Fagus pathway. In summary, the distribution of closely related coeval fossil taxa provides convincing evidence that Iceland was colonized both from the east (Eurasia) and the west (North America/Greenland) in the Cainozoic. 4.6 Comparison to Coeval northern Hemispheric Floras Many well-studied Middle Miocene floras of the northern hemisphere are situated at lower latitudes than the floras from Selárdalur and Botn. During the Middle Miocene the thermal gradient from low to high latitudes was not as pronounced as 4.6 Comparison to Coeval Northern Hemispheric Floras 187 today and earliest signals of ice rafted debris in the northernmost North Atlantic are from 14 Ma (Thiede et al. 1998). Hence, mid and high latitude floras shared a number of warm temperate taxa such as Aesculus, Carpinus, Platanus, and Pterocarya (Table 4.3). Nevertheless, a latitudinal gradient in vegetation and climate can be expected. At present, the mid-Miocene floras from Iceland are situated close to the Arctic Circle (66°33¢N). Table 4.3 Taxa of the 15 Ma floras from Iceland that are shared with some mid-Miocene floras of the northern hemisphere (Data from Tanai and Suzuki 1963; Christensen 1975, 1976, 1978; Wolfe and Tanai 1980; Koch 1984; Friis 1985; Gray 1985; Rember 1991; Liu and Leopold 1992; Liu et al. 1996; Kvaček and Rember 2000, 2007; Sun et al. 2002; Liang et al. 2003; Kovar-Eder et al. 2004) 1 Søby 2 Seldov 3 Abura 4 Clarkia 5 Parsch 6 Shanw + + + + + + Acer + + + Aesculus + + + + + + Alnus + + + + + + Betula + + + + Carpinus + Cathaya + + + + Cercidiphyllum Cryptomeria + + + + + Fagus + + + + Glyptostrobus + + Ilex Juniperus ? Liliaceae + + + Magnolia + Parthenocissus + + + + Picea + + + + + Pinus + + + + Platanus + + Polypodiaceae + + + + Pterocarya + + Rhododendron + + + + Rosaceae + + + + Salix Sanguisorba + + Sequoia Tetracentron + + + + + Tilia + + + + Tsuga + + + + + + Ulmus Viburnum Taxa in bold are recorded from Iceland only. 1 Søby flora, Denmark [56°21¢N]; 2 Seldovian Point flora, Alaska [59°26¢N]; 3 Abura flora, Hokkaido (Japan) [ca. 42°N]; 4 Clarkia flora, Idaho USA) [47°00¢N]; 5 Parschlug flora, Austria [47°29¢N]; 6 Shanwang flora, China [36°54¢N] 188 4 The Archaic Floras In the following section, the Icelandic floras are compared to a number of northern hemisphere floras situated between 30°N and 60°N. Closest is the Seldovia Point flora from Alaska described by Heer (1869), Wolfe (1966), Wolfe et al. (1966), and Wolfe and Tanai (1980) at around 60°N. Compared to the Icelandic floras, the Seldovia Point flora is more diverse at the generic level (33 vs. 46 genera, Appendix 4.1), and based on the macrofossil record (according to the treatment of Wolfe and Tanai 1980), has some warm temperate/subtropical elements that are entirely absent from the Icelandic floras (Alangium, Cladrastis, Cocculus, Table 4.4; Table 4.4 Taxa missing from Iceland shared by two or more mid-Miocene floras located more southerly than Iceland (Data from Tanai and Suzuki 1963; Christensen 1975, 1976, 1978; Wolfe and Tanai 1980; Koch 1984; Friis 1985; Gray 1985; Rember 1991; Liu and Leopold 1992; Liu et al. 1996; Kvaček and Rember 2000, 2007; Sun et al. 2002; Liang et al. 2003; Kovar-Eder et al. 2004) 1 Søby 2 Seldov 3 Abura 4 Clarkia 5 Parsch 6 Shanw + + + + Ailanthus (Simaroubaceae) + + Alangium (Alangiaceae) + + + Anacardiaceae + + + + Castanea (Fagaceae) + + Celastrus (Celastraceae) + + + + Celtis (Celtidaceae) + + + Cornus (Cornaceae) + + + Diospyros (Ebenaceae) + + + + Engelhardia Juglandaceae) + + Eucommia (Eucommiaceae) + + Euonymus (Celastraceae) + + + + + + Fabaceae + + Flacourtiaceae + + + + + + Fraxinus (Oleaceae) + + Halesia (Styracaceae) + + + + Hydrangea (Hydrangeaceae) + + Kalopanax (Araliaceae) + + + Keteleeria (Pinaceae) Liquidambar (Hamamelidaceae) Menispermaceae Metasequoia (Cupressaceae) Myricaceae Nyssa (Nyssaceae) Ostrya (Betulaceae) Paulownia (Paulowniaceae) Rhamnaceae Symplocos (Symplocaceae) Taxodium (Cupressaceae) Theaceae Vitis (Vitaceae) Zelkova (Ulmaceae) + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 1 Søby flora, Denmark [56°21¢N]; 2 Seldovian Point flora, Alaska [59°26¢N]; 3 Abura flora, Hokkaido (Japan) [ca. 42°N]; 4 Clarkia flora, Idaho USA) [47°00¢N]; 5 Parschlug flora, Austria [47°29¢N]; 6 Shanwang flora, China [36°54¢N] 4.6 Comparison to Coeval Northern Hemispheric Floras 189 Appendix 4.1). Also lianas are more diverse in the Seldovia Point flora as compared to Iceland (three vs. one taxon). At the same time, the Icelandic floras appear to be much richer in conifers (eight vs. three taxa). Overall, the similarity between these two floras appears quite high; both represent mixed broadleaved deciduous and coniferous forests. Among the broadleaved deciduous elements Acer, Betulaceae, Fagus, and Ulmus are important (Table 4.3). Another mid-Miocene flora well comparable to the Icelandic floras is the Abura flora from Hokkaido, Japan (ca. 42°30¢N; Tanai and Suzuki 1963). The Abura flora shares some taxa that are missing from Iceland with the Seldovia Point flora (Hydrangea, Menispermaceae) and with the much richer floras from Shanwang, China; Clarkia, Idaho, USA; and Parschlug, Austria (e.g., Ailanthus, Fabaceae, Hydrangea, Theaceae; see Table 4.4). At the same time, the high amount of broadleaved deciduous taxa, with Acer, Betulaceae, and Ulmus playing an important role, and several conifers is shared between the Abura and the Icelandic floras. The fact that the Abura flora is situated much more to the south than the Icelandic floras could reflect a northward shift of the temperate climate zone at the western margin of Eurasia already during the Middle Miocene. Today, temperate vegetation (Cfa and Cfb climates) extends much farther north along the western margin of Eurasia than along its eastern margin (Kottek et al. 2006); this anomaly is attributed to the warm Gulf Stream along the western margin of Eurasia. In contrast, the Søby flora of Denmark (56°21¢N; Christensen 1975, 1976, 1978; Koch 1984; Friis 1985) which is geographically closest to Iceland is more diverse than the Icelandic floras and shares a substantial number of elements that are absent from Iceland with mid latitude floras typically representing mixed mesophytic forests (e.g. Fabaceae, Flacourtiaceae, Nyssaceae, Styracaceae, and Symplocaceae; the latter three usually require taphonomic conditions of carpofloras for recognition, Appendix 4.1). For this reason, Mai (1995) included the Fasterholt-Søby floras within the Central European Middle Miocene mixed mesophytic forests and recognized that these floras represent the northernmost occurrences of the (humid warm temperate or subtropical) “Mastixioid floras” (Mai 1995, p. 369). The North American Clarkia flora (47°00¢N; Gray 1985; Rember 1991; Kvaček and Rember 2000, 2007) and the Central European Parschlug flora (47°29¢N; Kovar-Eder et al. 2004) are markedly more diverse than the Icelandic flora. These two floras and the eastern Chinese Shanwang flora (36°54¢N; Liu and Leopold 1992; Liu et al. 1996; Sun et al. 2002; Liang et al. 2003) are representing typical mixed mesophytic forests. They share a relatively large number of taxa not recorded from Iceland (Table 4.4). At the same time, the Clarkia flora has most taxa in common with the Icelandic flora (Table 4.3). Manchester (1999) listed the geographic and stratigraphic distribution of selected conifer and angiosperm genera in the northern hemisphere. For the Miocene, 28 genera are shared between Europe and North America, of which ten genera are also found in Iceland (Acer, Alnus, Betula, Cercidiphyllum, Comptonia, Fagus, Glyptostrobus, Liriodendron, Pterocarya, and Tilia). All these genera, including members of the largely evergreen families Magnoliaceae (Liriodendron), Myricaceae (Comptonia), and the taxodiaceous genus Glyptostrobus, are deciduous. Among the taxa not present in Iceland, Ailanthus, Hydrangea, 190 4 The Archaic Floras Gordonia, Liquidambar, Symplocos, and the palm genus Sabal are typical (compare Manchester 1999 and Appendix 4.1). In total, the mid-Miocene floras of Iceland show some overall similarities to a number of mid latitude floras from Eurasia and North America but lack typical thermophilic elements shared among most of the mid latitude floras (Table 4.4). A number of taxa recorded from Iceland but absent from coeval floras of other regions may have occurred in these floras as well but have been overlooked due to their inconspicuous, small pollen (Tetracentron; cf. Grímsson et al. 2008), or misidentified in case of Cathaya (cf. Liu and Basinger 2000; Saito et al. 2000; Hofmann et al. 2002). In addition, there is a noticeable similarity of the ca 15 Ma Icelandic floras with a number of Early to Middle Miocene floras from Arctic North America (situated well above 60°N; Matthews and Ovenden 1990; Fyles et al. 1994; White and Ager 1994) and, among others, the Early Miocene mid latitude flora from Brandon Lignite, eastern North America (Tiffney 1994; Traverse 1994; Table 4.5; Appendix 4.2). Some of the Arctic North American floras are less suitable for comparison with Icelandic ca 15 Ma floras because they represent azonal wetlands and aquatic vegetation with large amounts of herbaceous plants (Ballast Brook Formation and Mary Sachs Gravels, Banks Island; West River, Horton River area, Northwest Territories; Table 4.5, Appendix 4.2). Fyles et al. (1994) suggested that the Middle Miocene Ballast Brook beds represent a cypress swamp type of environment. Taxa such as Liriodendron, Comptonia, and Decodon recorded in these floras occur in younger Icelandic floras (see Chaps. 5, 6). In contrast, Whitlock and Dawson (1990) reported a palynoflora from the Early Miocene Haughton Formation from Devon Island at about 75°N that resembles more the floras of Iceland (Table 4.5). These authors interpreted some of the pollen and spores as reworked from older sediments (e.g. Gleichenidites). Furthermore, based on the absence in the macroflora, they assumed single pollen grains of Liquidambar, Castanea, Platanus, and Ilex to be derived from distant (more southerly) sources. From Devon Island, the only early Neogene vertebrate remains from Arctic North America have been recovered: two salmoniform fishes (trout, Eosalmo sp., and a smelt-like fish, cf. Osmerus sp.), one swan (tribe Cygnini), and four representatives of mammals (a shrew, family Soricidae, subfamily Heterosoricinae, cf. Domnina sp., a rabbit, family Leporidae, similar to some North American species referred to the extinct genus Desmatolagus, a rhinoceros, and a specimen of uncertain affinity; Whitlock and Dawson 1990). A Dfa to Dfb climate has been inferred for the Haughton Formation but the interpretation of both the plant and animal record remains rather unsatisfying. The closest match to the Middle Miocene floras of Iceland is seen in the flora of the Upper Rampart Canyon of the Porcupine River in central Alaska (White and Ager 1994; Table 4.5, Appendix 4.2). This flora is situated at approximately the same latitude as the Icelandic floras and radiometrically dated to 15.2 ± 0.1 Ma. Owing to the absence of a topographic barrier between central Alaska and the Pacific, the climate was oceanic and favoured a type of vegetation similar to the one from Iceland. Today, the Rampart Canyon is exposed to a cold continental Dsc 4.6 Comparison to Coeval Northern Hemispheric Floras 191 Table 4.5 Taxa shared between the mid-Miocene floras of Iceland and Early to Middle Miocene floras from Arctic and temperate North America (Data from Matthews and Ovenden 1990; Whitlock and Dawson 1990; Fyles et al. 1994; White and Ager 1994) 1 Porcupine 2 Ballast 3 West R. 4 Mary S. 5 Haughton 6 Brandon + + Acer Aesculus + + + + Alnus + + + + + Betula + + Carpinus +a Cathaya + Cercidiphyllum Cryptomeria Fagus Glyptostrobus Ilex Juniperus Liliaceae Magnolia Parthenocissus Picea Pinus Platanus Polypodiaceae Pterocarya Rhododendron Rosaceae Salix Sanguisorba Sequoia Tetracentron Tilia Tsuga Ulmus Viburnum + + + + + + + + + + + + + + + + + + + [+] + + + + + + + + + + + + + + + + + + + + + Taxa in bold are recorded from Iceland only. 1 Porcupine River, C Alaska [67°20¢N, 142°20¢W], Middle Miocene; 2 Ballast Brook Formation, Banks Island [74°20¢N, 123°15¢W], Middle Miocene; 3 West River, Horton River area, N. W. Territories [69°12¢N, 127°02¢W], late Early Miocene; 4 Duck Hawk Bluffs, Mary Sachs gravels, Banks Island [71°57¢N], late Early Miocene; 5 Haughton Formation, Devon Island [75°22¢N, 89°40¢W], Early Miocene; 6 Brandon Lignite, Vermont [43°50¢N, 73°03¢W], Early Miocene a As Abietineaepollenites baileyanus (Traverse) Zhu, A. microalatus Potonié, and Pinuspollenites tenuextimus (Traverse) Traverse climate sensu Köppen with a MAT of −8.6°C (as compared to the Cfc climate with MAT 5.5°C for the Vestmannaeyjar Islands in the south of Iceland; Fig. 4.6). For the richest plant bearing layer (organic bed 3) yielding thermophilous woody angiosperms such as Fagus, Quercus, Carya, Carpinus, Castanea-type, Ceridiphyllum, Juglans, Liquidambar, cf. Nyssa, Tilia-type, and Ulmus-type, White and Ager 192 4 The Archaic Floras (1994) suggest a MAT of 9–10°C or even warmer. The modern analogue for this flora would be in the warm range of the “Mixed Northern Hardwood Forest” sensu Wolfe (1979), or the cool range of the “Mixed Mesophytic Forest” sensu Wolfe. Finally, the Early Miocene flora of Brandon Lignite, Vermont, eastern North America (Tiffney 1994; Traverse 1994; Graham 1999), provides an example for a flora that may in part have acted as source vegetation for Arctic floras from Alaska to Devon Island and Iceland (Appendix 4.2). Taxa shared between the Brandon Lignite and 15–12 Ma floras from Iceland are, among others, Cathaya, Corylus, Fagus, Magnolia, Parthenocissus, Pterocarya, Rhododendron, and Tilia. Western North American Miocene floras may have acted as source vegetation as well (cf. Seldovia Point Flora, Table 4.3, Appendix 4.1, or the Miocene floras from the Columbia Plateau, Oregon, described by Chaney and Axelrod 1959). Fagus idahoensis and F. washoensis from the Columbia Plateau resemble most closely F. friedrichii from Alaska and Iceland (Grímsson and Denk 2005; Denk and Grimm 2009). The presence of Fagus in Miocene sediments from western North America, western Alaska, central Alaska, and Banks Island, may point to a possible pathway for Fagus to Iceland via Greenland (although Miocene plant bearing sediments are lacking from Greenland). 4.7 early Colonization of Iceland From the foregoing, we can proceed to consider scenarios for the early colonization of Iceland. In view of the traditional notion that Iceland was an isolated island by the Middle Miocene (Nilsen 1978; McKenna 1983a, b) we need to assess how an early colonization of Iceland would physically have been achievable. Evaluating the dispersal mechanisms of all the taxa shows that at least some (Aesculus, Fagus) could not have possibly colonized Iceland crossing large ocean barriers. Furthermore, most anemochorous taxa recorded have a very limited dispersal radius (Cathaya, Glyptostrobus, Acer, Carpinus, Cercidiphyllum, Fraxinus, Platanus, Tetracentron, Tilia, Ulmus; cf. Ridley 1930; van der Pijl 1982; Grímsson and Denk 2007). Generally, only a few taxa from the ca 15 Ma formation have dispersal modes conducive to transport over long distances (Betula, Salix, Rhododendron). The remaining taxa are dispersed by animals over short distances (Fagus, Aesculus; mammals) or long distances in various ways (Ilex, Lonicera, Magnolia, and Parthenocissus by birds, endozoochory; Platanus by mammals or birds, exozoochory). This suggests that when proto-Iceland was colonized, it was connected to the mainland or accessible via a chain of islands. This land was part of the Greenland-Scotland Transverse Ridge that persisted from the early Cainozoic into the Miocene (Poore 2008; see Chap. 12 for a more comprehensive discussion). The oldest exposed volcanic rocks on Iceland are ca 16 Ma. The sediments containing the oldest floras are approximately 15 Ma (McDougall et al. 1984; Hardarson et al. 1997; Kristjansson et al. 2003). Interestingly, a considerable number of the genera (Glyptostrobus, Aesculus, Platanus, Ulmus, Magnolia etc.) had 4.8 Summary 193 also been present in the older Brito-Arctic Igneous Province (BIP) floras (Spitsbergen; Heer 1883; Schloemer-Jäger 1958; Greenland; Koch 1963; Scotland; Boulter and Kvaček 1989), although these floras are at least 20 million years older. Considering a subaerial Greenland-Scotland Transverse Ridge (including protoIceland) long before 16 Ma (Poore 2008; see Fig. 12.2, Chap. 12), it is most likely that some of the species from the oldest floras migrated to proto-Iceland prior to the Middle Miocene and persisted until the accumulation of the ca 15 Ma sedimentary rock formation. The taxa recorded in the oldest sedimentary rocks in Iceland may have different geographical and temporal origins. Fossils similar to Aesculus and Cercidiphyllum recorded from Iceland were elements of the Palaeogene BIP floras and might have persisted in this area over a long time. In contrast, Fagus friedrichii with clear biogeographic affinities to Alaska, most likely colonized Iceland in the course of the Middle Miocene via North America and Greenland (Denk and Grimm 2009). 4.8 Summary In this chapter the floristic composition and palaeoecology of the oldest floras from Iceland are reviewed. Although the Middle Miocene floras from Iceland are not as rich in species as co-eval mid latitude floras, they point to the presence of warm temperate broad leaved deciduous and evergreen forest with a strong component of conifers in Iceland during the Langhian stage. The temperature requirements (MAT) of the taxa recorded are between 8°C and 12°C for upland environments and up to 15°C for lowland riparian elements. Furthermore, the position of Iceland in the North Atlantic would suggest that rainfall was evenly distributed over the year as it is today (Cf climate type sensu Köppen). A taxonomic evaluation of Icelandic fossils and comparable modern and fossil taxa suggests that at least some taxa reached Iceland from Eurasia (Cryptomeria and Rhododendron ponticum type), whereas others migrated from North America (Fagus friedrichii and Tetracentron atlanticum). The presence of chiefly dyschorous taxa (Aesculus, Fagus) and anemochorous taxa with short dispersal radii (Cathaya, Glyptostrobus, Acer, Carpinus, Cercidiphyllum, Fraxinus, Platanus, Tetracentron, Tilia, Ulmus) points to the presence of a physical link between both North America-Greenland and Iceland, and Europe and Iceland during the time at which proto-Iceland was colonized. 194 4 The Archaic Floras Appendix 4.1 Floristic composition of the 15 Ma sedimentary formation of Iceland compared to contemporaneous northern hemispheric fossil assemblages at latitudes below 60°N (Floral lists from Tanai and Suzuki 1963; Wolfe and Tanai 1980; Gray 1985; Rember 1991; Liu and Leopold 1992; Liu et al. 1996; Kvaček and Rember 2000, 2007; Sun et al. 2002; Liang et al. 2003; Kovar-Eder et al. 2004). Selárdalur-Botn flora, Iceland [65°46¢n] 15 Ma This study 1 Polypodium sp. 1 Polypodiaceae gen. et spec. indet. 1 1 Cathaya sp. 1 Cryptomeria sp. 1, 2 Glyptostrobus europaeus 1 Juniperus sp. 2 ?Picea sp 1 Pinus sp. 1 Diploxylon 1, 3 Sequoia abietina 1 Tsuga sp. 1 Acer sp. 1 (Sect. Acer) 1 Acer sp. 2 2 Aesculus sp. 1 Alnus sp. 1 1 Betula sp. 1 1 Carpinus sp. 1 1, 3 Cercidiphyllum sp. 1, 2 Fagus friedrichii 1 Ilex sp. 1 3 Lonicera sp. 1 Liliaceae gen. et spec. indet. 1 2 cf. Magnolia sp. 1 Parthenocissus sp. [L] 1, 3 Platanus leucophylla Pterocarya sp. 1 1, 3 Rhododendron sp. 1 1 Rosaceae gen et. spec. indet. 1 Rosaceae get et spec. indet. 2 1 1 Rosaceae get et. spec. indet. 3 1 Salix sp. 1 1 Sanguisorba sp. Tetracentron atlanticum 1 1, 3 Tilia selardalense 1, 3 Ulmus sp. MT1 1 Viburnum sp. Søby flora, Denmark [56°21¢n] Pre Late Badenian (Langhian) Koch 1984 [1]; Friis 1985 [2]; Christensen 1975, 1976, 1978 [3] 1 Abietinaepollenites microalatus 1 Piceapollenites alatus 1, 2 Pinus thomasiana 1 Sciadopityspollenites serratus 1 Sequoiapollenites polyformosus 2 Taxodium dubium 1 Taxodiaceaepollenites hiatus 1 Tsugaepollenites sp. 2 Hellia (Tetraclinis) salicornioides 3 Acer soebyensis 2 Alismataceae 1 Alnipollenites versus 2 Carex sp. 2 2 Carex sp. 3 1 Caryapollenites simplex 3 Castanea atavia 2 Cephalanthus pusillus 2 Cladiocarya europaea 2 Cladiocarya trebovensis 3 Comptonia acutiloba 2 Comptonia srodoniowae 1 Cyrillaceaepollenites megaexactus Cyrillaceaepollenites exactus 1 3 Diospyros brachysepala Dulichium marginatum 2 1 Engelhardtioipollenites spp. 1 Ericipites sp. Fraxinus cf. ungeri 3 2 Halesia crassa 2 Hypericum danicum Ilexpollenites iliacus 1 3 Juglans acuminata Juglans juglandiformis 3 2 Leguminocarpon sp. (continued) Appendix 4.1 Søby flora, Denmark (continued) 1, 3 Liquidambar europaea 2 Ludwigia corneri 2 Lysimachia sp. 3 Magnolia sp. 2 Microdiptera sp. 1, 2 Myrica sp. 1 Nyssapollenites sp. 1, 2 Platanus neptunii 2 Poliothyrsis eurorimosa 1 Polyporopollenites carpinoides 2 Potamogeton heinkei 2 Proserpinaca brevicarpa 1 Pterocaryapollenites stellatus Quercoidites henrici 1 1 Quercoidites microhenrici 1 Rhoipites pseudocingulum 3 Salix lavateri 1 Sapotaceoidaepollenites sp. 2 Saururus bilobatus 2 Scirpus ragozinii 1, 3 Smilax weberi 1, 2 Symplocos gothanii 2 Teucrium sp. 2 1 Triporopollenites coryloides 1 Trivestibulopollenites betuloides 1, 3 Ulmus pyramidalis 3 Carpinus seldoviana 3 Carya bendirei 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Celtis sp. Cercidiphyllum alaskanum Cladrastis cf. aniensis Cocculus auriculata Corylus sp. Crataegus chamisonii Cyclocarya ezoana Decodon alaskana Eucommia cf. Montana Fagus aff. crenata Fagus antipofi Fraxinus kenaica Hemitrapa borealis Hydrangea sp. Kalopanax acerifolium Liquidambar pachyphylla Lonicera sp. Monocotylophyllum alaskanum Monocotylophyllum spp. Nymphar ebae Nyssa cf. knowltoni Ostrya cf. oregoniana Platanus bendirei Populus kenaiana Populus sp. Potamogeton alaskanus Prunus aff. padus Prunus kenaica Pterocarya nigella Pueraria miothunbergiana Quercus furuhjelmi Salix cappsensis Salix hopkinsi Salix picroides Salix seldoviana Sorbaria hopkinsi Tilia subnobilis Ulmus knowltoni Ulmus owyheensis Ulmus sp. Ulmus speciosa Vitis seldoviana Zelkova brownii Zelkova ungeri 195 Seldovian Point flora, Alaska [59°26¢n] Late Early to early Middle Miocene Wolfe and Tanai 1980 3 Dryopteris sp. 3 Onoclea sensibilis 3 Glyptostrobus europaeus 3 Ginkgo biloba 3 Acer ezoanum oishi & Huzioka 3 Acer glabroides 3 Acer grahamensis 3 Acer heterodentatum 3 Alangium mikii 3 Alisma seldoviana 3 Alnus cappsi 3 Alnus fairi 3 Alnus healyensis 3 Betula cf. sublutea 196 Abura flora, Hokkaido (Japan) [ca. 42° n] Middle Miocene Tanai and Suzuki 1963 3 Abies aburaensis 3 Abies n-suzukii 3 Glyptostrobus europaeus 3 Keteleeria ezoana 3 Metasequoia occidentalis 3 Picea hyamensis 3 Picea kaneharai 3 Picea kanoi 3 Picea magna 3 Picea ugoana 3 Pinus miocenica 3 Pseudotsuga ezoana 3 Thuja nipponica 3 Tsuga aburaensis 3 Tsuga miocenica 3 Acer ezoanum 3 Acer fatsiaefolia 3 Acer megasamarum 3 Acer miohenryi 3 Acer palaeodiabolicm 3 Acer protojaponicum 3 Acer prototataricum 3 Acer pseudoginnala 3 Acer subpictum 3 Aesculus majus 3 Ailanthus yezoense 3 Alnus miojaponica 3 Alnus protomaximowiczii 3 Betula sublutea 3 Camellia protojaponica 3 Carpinus miofangiana 3 Carpinus subcordata 3 Carpinus subyedoensis 3 Carya miocathayensis 3 Castanea miomollissima 3 Cercidiphyllum crenatum 3 Comptonia naumanni 3 Corylus macquarrii 3 3 3 3 3 3 3 3 3 Fagus antipofi Fraxinus wakamatsuensis Hemitrapa borealis Hydrangea lanceolimba Juglans shanwangensis Liquidambar miosinica Magnolia miocenica Menispermum sp. Ostrya shiragiana 3 Populus reniformis 3 3 3 3 3 3 3 3 Pterocarya ezoana Robinia nipponica Rosa usyuensis Sassafras subtriloba Tilia protojaponica Ulmus longifolia Ulmus shiragica Zelkova ungeri 4 The Archaic Floras Clarkia flora, Idaho (USA) [47°00¢n] Middle Miocene Gray 1985 [1]; Rember 1991; Kvaček & Rember 2000, 2007 [3] 1 Lycopodium sp. 1 Isoetes sp. 1 Osmunda sp. 1 Polypodium vulgare type 1, 3 Abies chaneyi 3 Amentotaxus californica 3 Calocedrus masonii 1 Cedrus sp. 3 Cephalotaxus sp. 3 Chamaecyparis linguaefolia 3 Cunninghamia chaneyi 1 Ephedra sp. 3 Glyptostrobus oregonensis 3 Keteleeria heterophylloides 3 Metasequoia occidentalis 1, 3 Picea sp. 1, 3 Pinus harneyana 1, 3 Pinus tiptonia 1, 3 Pinus wheeleri 1 Pseudotsuga 3 Sequoia affinis 1 Taxaceae-Cupressaceae-Taxaceae unspecified Taxodium dubium 3 3 Taxus sp. Thuja gracilis 3 1 Tsuga heterophylla 1, 3 Acer cf. macrophyllum 1, 3 Acer cf. pensylvanicum 1, 3 Acer chaneyi 1, 3 Aesculus sp. Ailanthus sp. 3 1, 3 Alnus relatus 3 Amelanchier coveus 1, 3 Betula fairii 1, 3 Betula vera (continued) 3 Populus nipponica Appendix 4.1 Clarkia flora, Idaho (USA) (continued) 1 Carya sp. 3 Caesalpinia spokanensis 1, 3 Castanea spokanensis 1 Celtis sp. 3 Cercidiphyllum crenatum 1 Chenopodiaceae gen. et spec. indet. 3 Cornus latahensis 1 Corylus sp. 3 Crataegus gracilens 1 Cyperaceae 3 Diospyros oregoniana 1 Engelhardia sp. 1 Ericaceae gen. et spec. indet. 1, 3 Fagus idahoensis 1, 3 Fraxinus sp. 3 Gleditsia sp. 3 Gordonia idahoensis 1 Gramineae 3 Gymnocladus sp. 3 Halesia/Symplocos 3 Heterosmilax sp. [L] 3 Hydrangea sp. 1, 3 Ilex sinuata 1, 3 Juglans lacunosa 3 Lauraceae gen. et sp. Indet. Lindera oregoniana 3 1, 3 Liquidambar pachyphyllum 1, 3 Liriodendron Hesperia 3 Lithocarpus simulata 1, 3 Magnolia cf. acuminata 1, 3 Magnolia dayana Morus sp. 3 Myrica 1 3 Nuphar sp. 1, 3 Nyssa copiana 1, 3 Nyssa hesperia 1, 3 Ostrya oregonia Palaeocarya olsoni 3 Paliurus hesperius 3 3 Paulownia Columbiana Persea pseudocarolinensis 3 1 Parthenocissus sp. 3 Philadelphus sp. 1, 3 Platanus dissecta 3 Populus lindgreni Prunus sp. 3 3 Pseudofagus idahoensis 1, 3 Pterocarya mixta 1, 3 Quercus payettensis 1, 3 Rhamnus sp. 1, 3 3 1 3 3 1 3 1 1 1, 3 1, 3 3 1, 3 1, 3 3 Rhus sp. Ribes sp. Rosaceae gen. et spec. indet. Salix hesperia Sassafras columbiana Shepherdia sp. Smilax sp. [L] Symplocos sp.? Tilia sp. Typha sp. Ulmus sp. Vaccinium sp. Vitis sp. [L] Zelkova oregonia Zizyphoides-Nordenskioldia 197 Parschlug flora, Austria [47°29¢n] Late Early to early Middle Miocene Kovar-Eder et al. 2004 3 Adiantum renatum 3 Osmunda parschlugiana 3 Pronephrium stiriacum 3 Salvinia cf. mildeana 3 ? Cathaya sp. 3 ? Cupressus sp. 3 Glyptostrobus europaeus 3 Pinus spp. div. 3 “Acacia” parschlugiana 3 “Celastrus” europaea 3 “Cornus” ferox 3 “Evonymus” latoniae 3 “Juglans” parschlugiana 3 “Quercus” daphnes 3 ? Chaneya sp. 3 ? Prinsepia sp. 3 Acer integrilobum 3 Acer pseudomonspessulanum 3 Acer sp. 3 Acer tricuspidatum 3 Ailanthus confucii 3 Ailanthus pythii 3 Alnus gaudinii 3 Alnus julianiformis 3 3 3 3 Antholithes stiriacus Berberis (?) ambigua Berberis teutonica Berchemia multinervis (continued) 198 Parschlug flora, Austria (continued) 3 Betula cf. dryadum 3 Buxus cf. egeriana 3 Cedrelospermum stiriacum 3 Cedrelospermum ulmifolium 3 Celtis japeti 3 Cercidiphyllum crenatum 3 cf. ? Gordonia oberdorfensis 3 cf. Rosa sp. 3 Cotinus (?) aizoon 3 Craigia bronnii 3 Cypselites sp. 3 Daphnogene polymorpha 3 Dicotylophyllum sp. 1 - 6 3 Engelhardia macroptera 3 Engelhardia orsbergensis 3 Fagus sp. 3 Fraxinus primigenia 3 Leguminosites dionysi 3 Leguminosites hesperidum 3 Leguminosites palaeogaeus 3 Leguminosites parschlugianus 3 Liquidambar europaea 3 Liquidambar sp. 3 Mahonia (?) aspera 3 Monocotyledoneae gen. et sp. indet. 3 Myrica lignitum 3 Myrica oehningensis 3 Myrica sp. 3 Nerium sp. 3 Paliurus favonii 3 Paliurus tiliifolius 3 Phaseolites securidacus 3 Platanus leucophylla 3 Podocarpium podocarpum 3 Populus populina 3 Populus sp. 3 Prinsepia serra 3 Quercus drymeja 3 Quercus mediterranea 3 Quercus zoroastri 3 Saportaspermum sp. 3 Smilax sagittifera 3 Ternstroemites pereger 3 Tilia longebracteata 3 Toxicodendron herthae 3 Ulmus parschlugiana 3 Ulmus plurinervia 3 Zelkova zelkovifolia 4 The Archaic Floras Shanwang flora, China [36°54¢n] Late Early to early Middle Miocene Liu & Leopold 1992 [1]; Liu et al. 1996 [2]; Sun et al. 2002 [3]; Liang et al. 2003 [1] 1 Osmunda sp. 1 2 1, 2 1 1 1 1 1 1 1 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1 2 2 1 2 1, 2 1, 2 1 2 2 2 2 2 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 2 1, 2 1 2 Polypodium type Pteris sp. Keteleeria ezoana Larix/Pseudotsuga Picea type 1 Picea type 2 Pinus spp. Tsuga sp. Taxodiaceae gen. et spec. indet. Ephedra sp. Acer diabolicum Acer florinii Acer miocaudatum Acer miodavidii Acer miohenryi Acer nordenskioldi Acer subpictum Acer trifoliatum Adenophera type Aesculus miochinensis Ailanthus youngii Alangium sp. Albizia miokalkora Alnus prenepalensis Alnus protomaximowiczii Altingia sp. Amelanchier sibirica Ampelopsis shanwangensis Aphananthe mioaspera Astronium truncatum Berchemia miofloribunda Betula mioluminifera Carpinus cf. miofangiana Carpinus chaneyi Carpinus megabracteata Carpinus miocenica Carpinus mioturczaninowii Carpinus oblongibracteata Carpinus shanwangensis Carpinus subcordata Carrierea calycina Carya miocathayensis Caryophyllaceae sp. Cercis miochinensis (continued) Appendix 4.1 Shanwang flora, China (continued) 2 Castanea miomollissima 1 Castanopsis/Castanea sp. 2 Catalpa szei 2 Celastrus mioangulatus 1, 2 Celtis angusta 1, 2 Celtis bungeana 2 Ceratophyllum miodemersum 2 Chukrasia subtabularis 2 Cinnamomum oguniense 2 Commersonia parabatramia 2 Cornus miowalteri 1, 2 Corylus macquarrii 2 Cotoneaster protozabelii 2 Crataegus miocuneata 2 Cyperacites sp. 2 Diospyros miokaki 1 Engelhardia sp. 2 Eriobotrya miojaponica 1, 3 Eucommia sp. 2 Euodia miosinica 2 Euonymus protobungeanus 1 Fagus sp. 2 Ficus longipedia 2 Ficus shanwangensis 2 Firmiana sinomiocenica 2 2 2 2 2 2 2 2 2 Fraxinus dayana Fraxinus microcarpa Gleditsia miosinensis Graminites sp. Gymnocladus miochinensis Hamamelis miomollis Hovenia miodulcis Hydrangea lanceolimba Indigofera cf. pseudotinctoria 2 1 2 2 1 1 1 1, 2 2 2 2 2 2 2 1, 2 2 1, 2 2 2 2 2 2 2 2 1, 2 1, 2 1, 2 1 1 2 2 1 1, 2 1, 2 1, 2 2 2 2 2 2 2 2 1 1, 2 1, 2 1, 2 2 2 1, 2 1, 2 Malus parahupehensis Melia sp. Meliosma obtusifolia Meliosma shanwangensis Myrica sp. Nyssa sp. Oleaceae gen. et spec. indet. Ostrya uttoensis Paliurus miosinicus Paulownia shanwangensis Phellodendron megaphyllum Physocarpus shandongensis Pistacia miochinensis Platycarya miocenica Pterocarya serrulata Podogonium knorrii Polygonum miosinicum Populus balsamoides Populus glandulifera Populus latior Populus simonii Potamogeton sp. Prunus miobrachypoda Pueraria miothunbergiana Q. miovariabilis Q. sinomiocenicum Quercus dissimilifolia Reveesia sp. Rhododendron sp. Rhus miosuccedania Rosa shanwangensis Rosaceae gen. et spec. indet. Salix angusta Salix masamunei Salix miosinica Sapindus shandongensis Shaniodendron subequale Sophora miojaponica Spiraea mioblumei Stachyurus parachinensis Tapiscia pseudochinensis Tetrastigma shantungensis Thymelaeaceae gen. et spec. indet. Tilia miochinensis Tilia miohenryana Tilia preamurensis Toona bienensis U. cf. multinervis Ulmus macrocarpa Ulmus miopumila 199 1, 2 Juglans acuminata 1, 2 Juglans miocathayensis 1, 2 Juglans shanwangensis 2 2 2 1 2 2 2 1, 2 1, 2 1, 2 1, 2 2 Kalopanax acerifolium Koelreuteria macrocarpa Koelreuteria miointegrifolia Ilex sp. Lindera paraobtusiloba Lindera shanwangensis Litsea grabaui Liquidambar miosinica Lonicera cf. japonica Lonicera hispida Magnolia miocenica Mallotus populifolia 200 Shanwang flora, China (continued) 1, 2 Ulmus paralaciniata 2 Wisteria fallax 2 Vitis romanetii 2 Zanthoxylum prunifolium 1, 2 Zelkova ungeri 2 Zizyphus miojujuba 4 The Archaic Floras Boldface indicates that the genus is present in the Selárdalur-Botn Formation. Grey shading indicates that the genus is present in the younger Brjánslækur-Seljá and TröllatungaGautshamar formations (12 and 10 Ma). 1 based on pollen, spores, 2 based on leaves and/ or fruit/seed fossils,3 based on leaf fossils Appendix 4.2 Floristic composition of the 15 Ma sedimentary formation of Iceland compared to contemporaneous northern hemispheric fossil assemblages at higher latitudes and to one older assemblage from eastern North America (Floral lists from Matthews and Ovenden 1990; Whitlock and Dawson 1990; Tiffney 1994; Traverse 1994; Fyles et al. 1994; White and Ager 1994; Graham 1999; Liu and Basinger 2000). Brandon Lignite, Vermont [43°50¢n] Early Miocene Tiffney 1994 [3]; Traverse 1994 [1]; Graham 1999 [1, 3] 1, 3 Alangium 3 Caldesia 3 Caricoidea (Cyperaceae) [extinct genus] 1, 3 Carya Castanea 1 Cathaya Clethra ? 3 Cleyera (Eurya) Corylus ? 3 Cyrilla Engelhardia 3 ericaceae 3 Euodia Fagus fern spores (unidentified) Glyptostrobus 1, 3 Gordonia Gramineae Horniella (Rutaceae) [extinct genus] 1, 3 Ilex (2 spp.) 3 Illicium Juglans Jussiaea Liquidambar Lyonia (?) 3 Magnolia (2 spp.) Manilkara (Sapotaceae) 3 Melliodendron 3 Microdiptera (Lythraceae) [extinct genus] Mimusops (Sapotaceae) Moroidea [extinct genus] Morus Nestronia (?) (Santalaceae) Nyssa (4 spp.) Oxydendrum (?) Parthenocissus Persea Phellodendron Pinus (haploxylon type) Pinus (sylvestris type) Planera Pterocarya Quercus Rhamnus Rhododendron Rhus Rosaceae (?) Rubus Sargentodoxa Siltaria (Fagaceae) [extinct genus] Symplocos (2 spp) Tilia Toddalieae (Rutaceae) Turpinia Ulmus Vaccinium Vitis (2 spp.) Zanthoxylum (3) Zenobia (Ericaceae) (continued) 3 1, 3 3 3 3 1, 3 1, 3 3 1, 3 3 1, 3 3 3 Appendix 4.2 Porcupine River, Central Alaska [67°20¢n] Middle Miocene, 15 Ma White and Ager 1994 1 Anaemia-type 1 Deltoidospora sp. 1 fungal spores 1 Laevigatosporites sp. 1 Lycopodium annotinum/complanatum 1 Osmunda sp. 1 Polypodiaceae/Dennstaedtiaceae 1 Sphagnum Abies sp. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Picea sp. (large) Picea spp. Pinaceae undiff. (bisaccates) Pinus (robust corpus) Pinus koraiensis-type Pinus spp. Sciadopitys Taxodiaceae (papillate) Taxodiaceae-CupressaceaeTaxaceae Tsuga canadensis-type Tsuga heterophylla-type Tsuga mertensiana Tsuga sp. ? Acer sp. A ? Acer sp. B ? Cornus sp. Alnus sp. (4-pored) Alnus sp. (5-pored) Alnus sp. (6-pored) Alnus sp. (7-pored) Betula sp. (<20 mm) Betula sp. (>20 mm) Carya sp. Castanea-type Cercidiphyllum sp. cf. Carpinus sp. cf. Corylus sp. cf. Galium sp. cf. Juncus sp. ericales Fagus sp. Ilex-type Iridaceae/Liliaceae Juglans sp. Larix/Pseudotsuga 1 1 1 1 1 1 1 1 1 1 Liquidambar sp. Ludwigia sp. Nymphaea sp. Nyssa sp. Pterocarya sp. Quercus sp. Rhus-type Salix sp. Tilia-type Ulmus-type 201 Ballast Brook Formation, Banks Island [74°20¢n] Middle Miocene Fyles et al. 1994 2 Azolla sp. 2 Salvinia sp. (?) 2 Glyptostrobus sp. 2 Juniperus sp. 2 Metasequoia sp. 2 Thuja sp. 2 Abies sp. 2 Larix sp. 2 Picea sp. 2 Pinus 3-needle type 2 Pinus contorta-banksiana type 2 Pinus densiflora-resinosa type 2 Pinus itelmenorum 2 Pinus paleodensiflora 2 Pinus sp. 2 Pinus subsect. eustrobi 2 Pseudotsuga sp. 2 Tsuga sp. 2 Coniferales undet. 2 Aldrovanda sp. 2 Alnus (Alnobetula) sp. 2 Alnus incana type 2 Alnus sp. 2 Andromeda polifolia 2 Aracispermum sp. (?) 2 Aracites 2 Aracites globosa 2 Aralia sp. 2 Betula apoda type 2 Carex spp. 2 cf. Paliurus 2 Cladium sp. 2 Comptonia sp. 2 Cornus canadensis type 2 Cornus stolonifera type (?) (continued) 202 Ballast Brook Formation, Banks Island (continued) 2 Damasonium type 2 Decodon gibbosus type 2 Decodon globosus type 2 Diervilla sp. 2 Dulichium sp. 2 Epigaea sp. 2 Epipremnum crassum 2 Epipremnum ornatum 2 Hamamelidaceae? 2 Hippuris sp. 2 Hypericum sp. 2 Juglandaceae Genus? 2 Liriodendron sp. 2 Menyanthes (< 2mm) 2 Menyanthes trifoliata 2 Microdiptera/Mneme type 2 Mitella sp. 2 Morus sp. 2 Myrica eogale type 2 Myrica sp. 2 Najas sp. (?) 2 Nigrella sp. 2 Nymphoides sp. 2 Phyllanthus sp. 2 Polanisia cf. sibirica 2 Potamogeton sp. 2 Potentilla sp. 2 Ranunculus lapponicus 2 Rubus sp. 2 Rynchospora sp. 2 Salix sp. 2 Sambucus sp. 2 Saururus sp. 2 Scirpus sp. 2 Sparganium sp. 2 Teucrium sp. 2 Tubela type 2 Weigelia sp. 2 Zenobia sp. 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 4 The Archaic Floras Picea sp. Pinus five-needle type undiff. Tsuga sp. Actinidia sp. Aracites globosa Aralia sp. Betula sp. Carex sp. Carex spp. Decodon sp. Hippuris sp. Lycopus sp. Menyanthes trifoliata Nuphar sp. Paliurus sp. Potamogeton sp. Rubus sp. Rumex sp. Sambucus sp. Solanum/Physalis type Sparganium sp. Weigela sp. Viola sp. Vitis sp. West River, Horton River, n.W.T. [69°12¢n] Early Miocene Whitlock and Dawson 1990 2 Chara/Nitella type 2 Metsequoia sp. 2 Abies sp. 2 Larix sp. Mary Sachs Gravels, Banks Island [75°57¢n] Early Miocene Matthews and Ovenden 1990 2 Glyptostrobus sp. 2 Metasequoia sp. 2 Metasequoia disticha 2 Taxodium sp. 2 Thuja occidentalis 2 Abies grandis 2 Larix omoloica 2 Larix sp. 2 Picea banksii 2 Picea sp. 2 Pinus five-needle type undiff. 2 Pinus funebris 2 Pinus itelmenorum 2 Pinus paleodensiflora 2 Actinidia sp. 2 Alnus (Alnobetula) sp. 2 Alnus incana 2 Andromeda polifolia 2 Aralia sp. 2 Arctostaphylos alpina/rubra type (continued) Appendix 4.2 Mary Sachs Gravels, Banks Island (continued) 2 Betula apoda 2 Betula arboreal type 2 Betula dwarf shrub type 2 Carex sp. 2 Chamaedaphne sp. 2 Chenopodium sp. 2 Cleome sp. 2 Comptonia spp. 2 Diervilla sp. 2 Dulichium vespiforme 2 Epipremnum crassum 2 Hypericum sp. 2 Juglans eocineria 2 Liriodendron sp. 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Ludwigia sp. Menyanthes small form Microdiptera/Mneme type Morus sp. Myrica (Gale) sp. Myrica eogale Paliurus sp. Phyllanthus sp. Polanisia sp. Potamogeton sp. Potentilla sp. Ranunculus (Batrachium) sp. Ranunculus hyperboreus Rubus sp. Rumex sp. Sagisma sp. Sambucus sp. Sedum sp. Sesuvium sp. Solanum/Physalis type Sparganium sp. Teucrium sp. Weigela sp. Verbena sp. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Brassicaceae Carya [Castanea] cf. Fagus cf. Fraxinus Chenopodiaceae Corylus type Cupressaceae Cyperaceae Dryopteris type ericales [Gleichenidites] [Ilex] Juglans Larix [Liquidambar] Lycopodium type Osmunda type ostrya/Carpinus Picea Pinus Pinus strobus type [Platanus]a Populus Potamogeton Pteridium type Pterocarya Quercus Salix Sparganium Sphagnum type Tsuga Ulmus/zelkov 203 Haughton Formation, Devon Island [75°22¢n] Early Miocene Whitlock and Dawson 1990 [1] 1 Abies 1 Acer 1 Alnus 1 Betula a Mentioned in text but not shown in pollen diagram Boldface indicates that the genus is present in the Selárdalur-Botn Formation. 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Tertiary stratigraphy and paleobotany of the Cook Inlet region, Alaska. United States Geological Survey Professional Paper, 398-A, 1–29. Ying, T. S., Ma, C. G., Li, L. Q., Zhang, Z. S., & Zhang, W. X. (1983). Studies on the Cathaya communities. Acta Botanica Sinica, 25, 157–170. explanation of Plates Plate 4.1 1–4. Selárdalur valley, Northwest Iceland, Selárdalur-Botn Formation (ca 15 Ma). 1. Selárdalur valley, view towards NE. 2. Mount Þórishlíðarfjall, base camp at valley floor, outcrop on slopes in centre. 3. Outcrop showing volcanic plant-bearing sediments. 4. Fossils preserved as impressions in volcanic rock. 5–8. Botn in Súgandafjörður, Northwest Iceland, Selárdalur-Botn Formation (15 Ma). 5. Botn Farm next to outcrop. 6. Outcrop showing organic-rich clastic sediments. 7. Alternation of organic-rich coal seams, siltstones, and ash layers. 8. Fossils preserved as compressions with intact organic material in clastic sediments Plate 4.2 1–3. Polypodium sp. 1. 1. Spore in LM, polar view showing monolete tetrad mark. 2. Spore in SEM, proximal polar view. 3. Detail of spore surface. 4–6. Polypodiaceae gen. et spec. indet. 1. 4. Spore in LM, equatorial view. 5. Spore in SEM, equatorial view. 6. Detail of spore surface Explanation of Plates 209 Plate 4.3 1–3. Cupressaceae gen. et spec. indet. 1 (Cryptomeria sp). 1. Pollen grain in SEM. 2. Detail of pollen grain surface. 3 Pollen grain in LM. 4–6. Cupressaceae gen. et spec. indet. 3 (Juniperus sp.) 4. Pollen grain in SEM. 5. Detail of pollen grain surface showing tectum with few orbiculae. 6. Pollen grain in LM. 7–9. Cupressaceae gen. et spec. indet. 3 (Juniperus sp.) 7. Pollen grain in SEM. 8. Detail of pollen grain surface. 9. Pollen in LM. 10–13. Cupressaceae gen. et spec. indet. 3 (Juniperus sp.) 10. Pollen in SEM. 11. Detail of pollen grain surface showing tectum with orbiculae. 12. Detail of pollen grain surface showing verrucate to regulate tectum elements with a microechinate suprasculpture around ulcus. 13. Pollen grain in LM Plate 4.4 1–3. Cupressaceae gen. et spec. indet. 2 (Glyptostrobus sp.) 1. Pollen grain in SEM. 2. Detail of pollen grain surface. 3. Pollen grain in LM. 4–6. Cupressaceae gen. et spec. indet. 2 (Glyptostrobus sp.) 4. Pollen grain in SEM. 5. Pollen grain surface with orbiculae. 6. Ruptured pollen grain in LM. 7–11. Glyptostrobus europaeus (Brongn.) Unger. 7. Seed cone (IMNH 4988). 8. Long-shoot (IMNH 4975). 9. Short-shoot (IMNH 4999). 10. Axes with scale leaves (IMNH 5002-01). 11. Epidermal cuticle with stomata (IMNH 5002-01). 12. Glyptostrobus pensilis (Staunton ex D. Don) K. Koch for comparison. Epidermal cuticle with stomata Plate 4.5 1–4. Cupressaceae gen. et spec. indet. 4 (Sequoia sp.) 1. Pollen grain in SEM showing leptoma with papilla. 2. Detail of papilla with orbiculae. 3. Pollen grain in LM. 4. Detail of pollen grain surface showing leptoma area. 5. to 8. Sequoia abietina (Brongn.) Knobl. 5. Leafy axis (IMNH 4998). 6. Detail showing alternate phyllotaxis (IMNH 4987). 7. Epidermal cuticle with stomata (IMNH 4979). 8. Epidermal cuticle without stomata (IMNH 4978) Plate 4.6 1–3. Cathaya sp. 1. Bisaccate pollen grain in SEM, polar view. 2. Detail of saccus. 3. Pollen grain in LM, polar view. 4–7. Pinus sp. 1 (Diploxylon type). 4. Bisaccate pollen grain in SEM, polar view. 5. Detail of corpus and saccus. 6.. Detail of corpus. 7. Pollen grain in LM. 8–10. Tsuga sp. 1. 8. Monosaccate pollen grain in SEM. 9. Detail of monosaccus and corpus, distal polar view. 10. Pollen grain in LM, polar view Plate 4.7 1–3. Ilex sp. 1. 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface in mesocolpium and aperture region. 3. Pollen grain in LM, equatorial view. 4–6. Ilex sp. 1. 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grain surface showing clavae with short striate suprasculpture in mesocolpium and aperture region. 6. Pollen grain in LM, equatorial view. 7–9. Alnus sp. 1. 7. Tetraporate pollen grain in SEM, polar view. 8. Detail of pollen grain surface. 9. Pollen in LM, polar view. 10–12. Alnus sp. 1. 10. Pentaporate pollen grain in SEM, polar view. 11. Detail of pollen grain surface. 12. Pollen grain in LM, polar view Plate 4.8 1–3. Alnus sp. 1. 1. Pollen grain in SEM, polar view. 2. Detail of pollen grain surface. 3. Pollen grain in LM. 4–6. Betula sp. 1. 4. Pollen grain in SEM, polar view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, polar view. 7–9. Betula sp. 1. 7. Pollen grain in SEM, equatorial view. 8. Detail of pollen grain surface. 9. Pollen grain in LM, oblique polar view. 10–12. Carpinus sp. 1. 10. Pollen grain in SEM, polar view. 11. Detail of pollen grain surface. 12. Pollen grain in LM, polar view Plate 4.9 1–3. Viburnum sp. 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, equatorial view. 4–6. Viburnum sp. 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grain surface. 6. Pollen grain in LM, equatorial view. 7–9. Viburnum sp. 7. Pollen grain in SEM, equatorial view. 8. Detail of pollen grain surface. 9. Pollen grain in LM, equatorial view 210 4 The Archaic Floras Plate 4.10 1–3. Ceridiphyllum sp. 1. Pollen grain in SEM, polar view. 2. Detail of pollen grain surface showing aperture membrane. 3. Detail of pollen grain surface showing microreticulum with irregularly distributed microechinae. 4. Pollen grain in LM, polar view. 5–6. Cercidiphyllum sp. 5. Leaf fragment (IMNH 6686-A01). 6. Detail showing crenate leaf margin (IMNH 6686-B01) Plate 4.11 1–3. Rhododendron sp. 1 (R. ponticum type). 1. Pollen tetrad in SEM. 2. Detail of tetrad surface showing microrugulate tectum. 3. Tetrad in LM. 4–7. Rhododendron sp. 1. 4. Pollen tetrad with viscin threads in SEM. 5. Detail of tetrad surface. 6. Tetrad in LM. 7. Detail of pollen grain surface showing tectum with viscin thread. 8. Rhododendron sp. 1. Detail of showing microrugulate tectum. 9. cf.. Rhododendron sp. (IMNH 289-04) Plate 4.12 1–12. Fagus friedrichii Grímsson and Denk. 1–6. Pollen. 1. Pollen grain in SEM, equatorial view. 2. Pollen grain in SEM, polar view. 3. Pollen grain in LM, equatorial view. 4. Pollen grain in LM, equatorial view. 5. and 6. Details of surface showing regulate tectum. 7–9. Cupules. 7. Pedunculate cupule showing position of two nutlets (IMNH 5001-02). 8. Cupule valve showing spine-like appendages (IMNH 4997). 9. Cupule valve showing recurved apical appendages (IMNH 5002-04). 10–12. Leaves. 10. Large wide elliptic leaf (IMNH 299). 11. Narrow elliptic leaf (IMNH 16). 12. Wide elliptic leaf (IMNH 782). 13. Bud scale (IMNH 5061) Plate 4.13 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. 7–9. Liliaceae gen. et spec. indet. 1. 7. Pollen grain in SEM, distal polar view. 8. Detail of pollen grain surface. 9. Pollen grain in LM. 10–12. Liliaceae gen. et spec. indet . 1. 10. Pollen grain in SEM, proximal polar view showing sulcus. 11. Detail of pollen grain surface. 12. Pollen in LM Plate 4.14 1, 2, 5 and 6. Platanus sp. 1. Tricolpate pollen grain in SEM, equatorial view. 2. Pollen grain in LM, equatorial view. 5. Detail of aperture membrane. 6. Detail of tectum. 3, 4, 7 and 8. Platanus sp. 3. Pollen grain in SEM, equatorial view. 4. Pollen grain in LM, equatorial view. 7. Detail of pollen grain surface showing closed reticulum. 8. Detail of pollen grain surface. 9. Platanus leucophylla (Unger) Knobloch, weakly lobed leaf (IMNH 302) Plate 4.15 1–3. Sanguisorba sp. 1. 1. Pollen grain in SEM, polar view. 2. Detail of pollen grain surface. 3. Pollen grain in LM, polar view. 4–6. Rosaceae gen. et spec. indet. 1. 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grain surface showing aperture region. 6. Pollen grain in LM, equatorial view. 7–9. Rosaceae gen. et spec. indet. 2. 7. Pollen grain in SEM, equatorial view. 8. Detail of pollen grain surface showing aperture region. 9. Pollen grain in LM, equatorial view. 10–12. Rosaceae gen. et spec. indet. 3. 10. Pollen grain in SEM, equatorial view. 11. Detail of pollen grain surface showing aperture region. 12. Pollen grain in LM, equatorial view Plate 4.16 1–3. Salix sp. 1. 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface showing wide reticulum and aperture rim. 3. Pollen grain in LM, equatorial view. 4–6. Salix sp. 1. 4. Pollen group in SEM. 5. Pollen group in LM. 6. Pollen group at higher magnification. 7–9. Salix sp. 1. 7. Pollen grain in SEM, equatorial view. 8. Detail of pollen grain surface close to aperture rim. 9. Pollen grain in LM Plate 4.17 1–3. Acer sp. 1. 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface showing striate tectum. 3. Pollen grain in LM, equatorial view. 4–6. Acer sp. 2. 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grain surface showing striate-rugulate tectum. 6. Pollen grain in LM, equatorial view. 7–9. Aesculus sp. 7. Large leaflet (IMNH 783). 8. Lower part of leaflet (IMNH 748). 9. Detail of 8. showing leaflet margin Explanation of Plates 211 Plate 4.18 1–4. Tilia sp. 1. Pollen grain in SEM, polar view. 2. Detail of aperture region showing tectum and aperture membrane. 3. Detail of pollen surface showing microreticulate tectum. 4. Pollen grain in LM, polar view. 5. and 6. Tilia selardalense Grímsson, Denk and Símonarson. 5. Leaf fragment with petiole and deeply cordate base (IMNH 5555). 6. Complete weakly lobed leaf (s.n.) Plate 4.19 1, 3 and 5. Ulmus sp. 1. Pollen grain in SEM, polar view. 3. Pollen grain in LM, polar view. 5. Detail of pollen grain surface around porus. 2, 4 and 6. Ulmus sp. 2. Pollen grain in SEM, polar view. 4. Pollen grain in LM, polar view. 6. Detail of pollen grain surface showing slightly annulate porus. 7–9. Ulmus sp. MT1 7. Leaf with serrate leaf margin (IMNH 304). 8. Detail of leaf margin (IMNH 305). 9. Leaf margin (IMNH 6684-03) Plate 4.20 1–3. Tetracentron atlanticum. 1. Pollen grain in SEM, equatorial view. 2. Detail of pollen grain surface showing striatoreticulate tectum and aperture. 3. Pollen grain in LM, equatorial view. 4–6. Parthenocissus sp. 4. Pollen grain in SEM, equatorial view. 5. Detail of pollen grain surface showing microreticulate to reticulate tectum in polar region. 6. Pollen grain in LM, equatorial view. 7–9. Pollen type 1. 7. Pollen grain in SEM, equatorial view. 8. Detail of pollen grain surface showing regulate/fossulate tectum. 9. Pollen grain in LM, equatorial view. 10–12. Pollen type 1. 10. Pollen grain in SEM, equatorial view showing smooth aperture rim. 11. Detail of fossulate tectum. 12. Pollen grain in LM, equatorial view 212 4 The Archaic Floras Plates Plate 4.1 Plates 213 Plate 4.2 214 4 The Archaic Floras Plate 4.3 Plates 215 Plate 4.4 216 4 The Archaic Floras Plate 4.5 Plates 217 Plate 4.6 218 4 The Archaic Floras Plate 4.7 Plates 219 Plate 4.8 220 4 The Archaic Floras Plate 4.9 Plates 221 Plate 4.10 222 4 The Archaic Floras Plate 4.11 Plates 223 Plate 4.12 224 4 The Archaic Floras Plate 4.13 Plates 225 Plate 4.14 226 4 The Archaic Floras Plate 4.15 Plates 227 Plate 4.16 228 4 The Archaic Floras Plate 4.17 Plates 229 Plate 4.18 230 4 The Archaic Floras Plate 4.19 Plates 231 Plate 4.20