Scanning electron microscopy investigations of middle to late Eocene pollen from the Changchang Basin (Hainan Island, South China) – Insights into the paleobiogeography and fossil history of Juglans, Fagus, Lagerstroemia, Mortoniodendron, Cornus, Nyssa, Symplocos and some Icacinaceae in SE Asia

Accepted Manuscript Scanning electron microscopy investigations of middle to late Eocene pollen from the Changchang Basin (Hainan Island, South China) – Insights into the paleobiogeography and fossil history of Juglans, Fagus, Lagerstroemia, Mortoniodendron, Cornus, Nyssa, Symplocos and some Icacinaceae in SE Asia

Christa-Ch. Hofmann, Tatiana M. Kodrul, Xiaoyan Liu, Jianhua Jin PII: DOI: Reference:

S0034-6667(18)30182-9 https://doi.org/10.1016/j.revpalbo.2019.02.004 PALBO 4052

To appear in:

Review of Palaeobotany and Palynology

Received date: Revised date: Accepted date:

9 August 2018 25 January 2019 10 February 2019

Please cite this article as: C.-C. Hofmann, T.M. Kodrul, X. Liu, et al., Scanning electron microscopy investigations of middle to late Eocene pollen from the Changchang Basin (Hainan Island, South China) – Insights into the paleobiogeography and fossil history of Juglans, Fagus, Lagerstroemia, Mortoniodendron, Cornus, Nyssa, Symplocos and some Icacinaceae in SE Asia, Review of Palaeobotany and Palynology, https://doi.org/10.1016/ j.revpalbo.2019.02.004

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ACCEPTED MANUSCRIPT Scanning electron microscopy investigations of middle to late Eocene pollen from the Changchang Basin (Hainan Island, south China) – insights into the palaeobiogeography and fossil history of Juglans, Fagus, Lagerstroemia, Mortoniodendron, Cornus, Nyssa, Symplocos

, Tatiana M. Kodrul b, c , Xiaoyan Liub,d, Jianhua Jin

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University of Vienna, Department of Palaeontology, Vienna, Austria

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State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources,

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a

a*

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Christa-Ch. Hofmann

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and some Icacinaceae in SE Asia.

and School of Life Sciences, Sun Yat-sen University, Guangzhou, China Geological Institute, Russian Academy of Sciences, Moscow, Russia

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Key Laboratory of Economic Stratigraphy and Palaeogeography, Chinese Academy of Sciences

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(Nanjing Institute of Geology and Palaeontology)

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* corresponding author

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c

ACCEPTED MANUSCRIPT Abstract Bartonian-aged samples from the Changchang Formation (Hainan) have been palynologically analysed using light microscopy (LM) and scanning electron microscopy (SEM). The presence of cf. Laurelia-type pollen demonstrates a wide geographical range for this family during the Eocene. A particular palaeobiogeographic pattern, suggesting Eurasia as the place of origin, can be seen

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from six pollen taxa: (1) A Flueggea-type, together with previously found European Flueggea fossils, (2) a Nyssa-type closely resembling the extant Nyssa sinensis and upper Eocene Nyssa

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pollen from Europe, (3) three Symplocos-types, which are closely related to the early diverging

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Symplocos subgenus Palura, resemble upper Eocene Symplocos pollen from Germany, and (4) a Cornus-type belonging to the “blue-or-white- fruited clade”, like several Cornus fossils from

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Europe. In contrast, an Asian palaeobiogeographic pattern can be seen from six Hainan taxa: (1)

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Two Phyllanthus subgen. Eriococcus/Isocladus-types, here described for the first time, that, so far, occur only in China, (2) a Lagerstroemia-type that resembles pollen of the Miocene Lagerstroemia

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cathayensis from China and pollen of two extant deciduous Lagerstroemia taxa, (3) a Juglans-type that is assumed to belong to Juglans section Cardiocaryon and (4) two Dipterocarpaceae pollen

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types (cf. Dipterocarpus and cf. Dryobalanops) that are here described for the first time from Eocene strata outside India. A much wider distribution can be observed with the Fagus-type pollen

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closely resembling pollen of the extant Fagus “subgenus Engleriana” and Paleogene Fagus pollen from Greenland and Canada, suggesting an amphipacific distribution of an ancient Fagus “Engleriana lineage” during the Eocene. The Craigia-type corroborates the presence of Craigia diaspores from the Changchang Formation and two Mortoniodendron-types reveal a particular palaeobiogeographical history; extant Mortoniodendron grows in Central America and is known there since the Miocene. However, Eocene Mortoniodendron-type pollen from Europe and now Hainan indicate a far wider distribution of this genus. The two Iodes types, one resembling African/Madagascar taxa and one a Melanesian taxon, suggest that the Old World disjunction of Iodes in Africa/Madagascar and SE Asia is a Paleogene relict, whereas the third Icacinaceae taxon resembles two genera of the Mappia/Nothapodytes clade, where Mappia occurs today in Central

ACCEPTED MANUSCRIPT America and Nothapodytes in SE Asia. keywords: middle - late Eocene pollen, SEM investigation; palaeobiogeography

1. Introduction In the Changchang Basin on northeast Hainan Island (south China; Figure 1) the terrestrial coal-bearing Changchang Formation overlies the Changtou Formation of inferred Paleocene age

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and is in turn overlain by the Wayao Formation of inferred Late Eocene age (Lei et al., 1992). Due

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to these uncertainties, the precise stratigraphic age of the Changchang Formation has been a matter

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of debate. Age estimates based on plant macrofossils and palynomorphs ranged from Paleocene to Oligocene (Guo, 1979; Yao et al. 2009, Zhang 1980). However, further investigations, based on

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comparisons with plant macro- and microfossils and vertebrate findings from known fossil localities on the mainland (Aleksandrova et al., 2015; Averianov et al., 2016, 2017; Danilov et al., 2013; Jin,

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2008, Skutschas et al., 2014; Tong et al., 2010, Wang et al., 2007), constrained the age of the Changchang Formation to the middle Eocene (Lutetian/Bartonian) (see summary in Aleksandrova

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et al., 2015; Spicer et al. 2014). The recent identification of Anthracokeryx naduongensis from the

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Youganwo Formation, which is taken to be contemporaneous with the Changchang Formation (Aleksandrova et al., 2015; Spicer et al. 2014), provides support for the early late Eocene age of the upper stratigraphic unit (oil shales) in this formation (Averianov et al., 2018).

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The plant fossil bearing Changchang Formation is composed of two parts: The lower part is a coal-bearing series of intercalated lake and paludal deposits, with a few layers of fluvial sandstones, and the upper part is dominated mainly by lacustrine mudstones and siltstones intercalated with fluvial, whitish-grey, grey-green and brownish-yellow sandstones (Spicer et al., 2014). A climate interpretation from fossil pollen data based on LM investigation using the Coexistence Approach (CoA) (Mosbrugger and Utescher, 1997) yielded an overall mean annual air temperature (MAT) for the whole Changchang Formation of 14.2–19.8 °C (Yao et al., 2009). In contrast, a subsequent multivariate analysis of the architecture of woody dicot leaves using the

ACCEPTED MANUSCRIPT Climate Leaf Analysis Multivariate Program (CLAMP: Wolfe, 1993; Kovach and Spicer, 1995; Spicer, 2008; Yang et al., 2011) reconstructed a higher MAT of ~22 ± 4.7 °C (2 sigma) with a minimum MAT of ~20 °C (data of Spicer et al., 2014).

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2. Methodology

Eight samples, representing the entire Changchang Formation, were investigated (lower

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part: samples V-1-1, IV-1-1, middle part: I-14-1, I-14-3, II-6-1, upper part: III-2-1, III-2-2, II-4-

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top; see a simplified sedimentary log of the section in Spicer et al., 2014). Sample material comprised predominantly coaly mudstones, mud- and siltstones and coal (sample collection and

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sediment characterisation by T.M. Kodrul and A.B. Herman in 2009). Sample preparation followed

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standard wet chemical procedures (Klaus, 1987): After crushing the samples with a mortar and pestle, the powder was boiled in HCl for five minutes in order to dissolve the carbonate part,

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washed three times with water and decanted and then treated with HF to dissolve the silicates (cold processing over four days), decanted and washed again three times with water. The organic remains

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were boiled in HCl for five minutes, decanted and washed several times with water, but not sieved, thus retaining palynomorphs <10µ in size. Successive bleaching with a sodium chlorate solution

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and five drops of HCL with subsequent acetolysis (nine parts of acetic acid anhydrite and one part sulphuric acid) in a hot water bath for five minutes reduced the amount of associated fragments of plant macrofossils. The remains were mixed with glycerine and kept in small, tightly closing glass vials. For LM investigation, the pollen were transferred with a micro-manipulator from a sample smear on a glass slide into a clean drop of glycerine on a new slide and photographed with a Samsung digital camera. After LM-photography, the same pollen were moved with a micromanipulator to an SEM stub and rinsed in a drop of 100% alcohol to remove the glycerine. The stubs were sputtered with gold and examined under the SEM (FEI InspectS 500). Stubs and photographs are stored in the Department of Palaeontology, University of Vienna, under inventory numbers IPUW 7836_Hai/2/1-10 to IPUW 7836_Hai/4/1-10.

ACCEPTED MANUSCRIPT The climate zones (e.g., Af, Am; Cfa, Cfb, Cwa etc.) in which the extant specific affiliations (nearest living relatives) of the fossil pollen taxa described here are the Köppen-Geiger classifications, updated by Kottek et al. (2006) and Rubel et al. (2017). The distribution data of extant taxa are taken from “World checklist of selected plants”, Royal Botanical Gardens, Kew (http://wcsp.science.kew.org), from www.tropicos.org., from the African plant database

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(version3.4.0)(www.ville- ge.ch/musinfo/bd /cjb/africa/) and from the Flora of China

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(www.efloras.org).

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3. Results

Of the eight samples analysed for palynomorphs, four were not at all diverse, because of bad

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preservation, yielding only a few fern taxa, oak-like Fagaceae, Juglandaceae and Pinaceae. The

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other four were characterized by very high percentages of Fagaceae pollen taxa (partly up to 80%), very similar to the results of Yao et al. (2009); these consistently high percentages reflect a forest

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vegetation dominated by various oak-like trees surrounding the lacustrine, coal-bearing setting for a

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long period.

3.1. Description and affiliation of the pollen types and the geographical occurrences and climatic

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conditions of present-day relatives.

The pollen grain descriptions and terminology used is after Hesse et al. (2009), if not stated otherwise, and phylogenetic relationships are after Stevens (2001, and onwards). A summary of the examined pollen types and their affiliations, the geographical occurrences and climatic conditions of the extant affiliations is shown in Table 1. Additional information on the palaeo-distribution of the examined taxa are briefly sketched in Figure 2.

Laurales Jussieu ex Berchtold et J. Presl Atherospermataceae R. Brown Laurelia Jussieu

ACCEPTED MANUSCRIPT cf. Laurelia-type (Plate I, 1-3) Description LM: Sulcate, boat-shaped pollen grain with an elliptic outline with pointed ends at the longer axis in a fossilized compressed state (Plate I, 1); long equatorial diameter ca. 28.9 µm and short equatorial diameter of 14.8 µm, long sulcus of ca. 26.2 µm length (Plate I, 1); wall thickness ca. 1.2 mm with the sexine as thick as nexine; reticulate. SEM: The ectexine is semitectate and

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micro-reticulate to reticulate (Plate I, 2), heterobrochate with roundish to slightly angular brochi ranging in size from 0.25 to 1.1 µm in diameter (Plate I, 2, 3); muri are simplicolumellate, ca. 0.8 to

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1.2 µm wide and ornamented with supratectal, angular micro-verrucae of ca. 0.25-0.35 µm in

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diameter, that are arranged in a faint crotonoid pattern (Plate I, 3). Occurrence: sample I 14-1, I-14-3.

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Remarks: The ectexine and size are similar to fossil Laurelia-type pollen from the lower Eocene of

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Krappfeld in Austria (Hofmann et al. 2015a, fig. 2 a-m) and to modern Laurelia novae zelandiae A. Cunningham and Laureliopsis (=syn. Laurelia) philippiana (Loser) Schodde, both of which have been investigated with SEM and TEM by Sampson (1975; 1996, fig. 1-8 and 9-13, respectively).

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However, Laurelia is a pollen with a typical ring-like aperture (“encircling meridionosulcate” after

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Sampson, 1996) that divides the grain into two equal halves, but it is rarely fossilized as a complete pollen grain because in a fossilized state this taxon is preserved mostly as rolled up halves that look

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like boat-shaped monocotyledonous or basal angiosperm pollen (Hofmann et al., 2015a). Habitat today: Undergrowth trees in the southern hemisphere, in either temperate, moist montane forests of Argentina and Chile (L. philippiana) or in slightly warmer submontane forests in New Zealand (Renner et al., 2000; Laurelia novae-zelandiae). Both today grow in the Cfb and Cfc climate zones.

Monocotyledons Arecales Bromhead Arecaceae Berchtold et J. Presl Coryphoideae Burnett

ACCEPTED MANUSCRIPT Trachycarpeae Satake Trachycarpeae-type (Plate I 4-5) Description LM: Sulcate, more-or-less boat-shaped pollen grain, slightly asymmetric elliptic outline in fossilized state (Plate I, 4); long equatorial diameter 29.2 µm and short equatorial diameter ca. 15.8 µm; long sulcus of ca. 26.6 µm length (Plate I, 4); wall thickness ca. 0.9 to 1.1 µm with the

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sexine as thick as to slightly thicker than nexine; reticulate. SEM: The ectexine is reticulate to micro-reticulate on the distal side of the pollen grain, heterobrochate with slightly angular roundish

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to elongated brochi (ca. 0.5 in width and to 1.5 µm in length), and foveolate towards the apices

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(Plate I, 5); muri are probably duplicolumellate, shallow, ca. 0.5 to 0.7 µm wide, and probably sit on very short columellae (not discernable), muri display a faint annelid pattern (perpendicularly

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arranged grooves); visible footlayer is smooth to uneven and faintly perforate (Plate I, 6).

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Occurrence: I-14-1.

Remarks: Under LM observation, this pollen taxon looks like the fossil morphotaxon Arecipites

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Wodehouse that is interpreted as a palm pollen. Overview- and detailed SEM images also point towards palms, in particular, to members of the tribe Trachycarpeae (Trachycarpus H. Wendland,

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Livistona R. Brown and Licuala Thunberg in Dransfield et al., 2008, page 253 fig. a, b; page 263 fig. a-d; page 264 fig. a-d, respectively; Licuala only: Ambwani and Kumar, 1993, fig. 1 K, L, S, T;

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Trachycarpus only: Wei, 2003, plate 13.1 figs. 4-7). Fossils assigned to Trachycarpus and Livistona are known since the early Eocene in Europe, Russia and India (see Dransfield et al., 2008, page 253, 263) and a fossil leaf fragment affiliated with Livistona sp. has been described, together with other corophyoid palm fossils, from the Changchang Formation by Zhou et al. (2013). Habitat today: Trachycarpus grows in warm to temperate areas (damp oak forests up to 2400 m asl) in India, northern Thailand, Vietnam and China in Cwa, Cwb, Cfa, Am and Aw climate zones, whereas Licuala reaches from tropical India to Queensland (Australia) to the Solomon Islands (Dransfield et al., 2008) and grows in Af, Am, Aw, Cfa, Cfb, Cwa, Cwb, BWh, and BSh climate zones, and Livistona is disjunctly distributed at the Horn of Africa and southwest Arabia (one taxon), and in the east from the eastern Himalayas to Japan, southwards via Indochina and Malesia

ACCEPTED MANUSCRIPT to northeastern Australia (Dransfield et al., 2008) and grows in Af, Am, Aw, Cfa, Cfb, Cwa, Cwb, BWh and BSh climate zones.

Malpighiales Martius Phyllanthaceae Martynov

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Phyllanthoideae Beilschmied Flueggea Willdenow

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Fluggea-type (Plate I, 7-9)

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Description LM: Tricolporate, prolate pollen grain, in equatorial view with an elliptic to circular outline in fossilized, compressed state (Plate I, 7); polar axis ca. 15.7 µm and equatorial axis 11.3

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µm long, colpus ca. 12.4 µm long, endoaperture circular ca. 1.5 µm in diameter (Plate I, 7); wall

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thickness ca. 0.8 µm; reticulate. SEM: In the mesocolpium and polar areas the ectexine is microreticulate to foveolate, heterobrochate with slightly angular and often elongated brochi (ca. 0.3 to

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0.5 µm width and up to 1.2 µm length; Plate I, 8), the margo is ca. 1 to 2.1 µm wide, conspicuously tectate with few perforations (Plate I, 8, 9); muri smooth, ca. 0.4 µm high and tapering thus

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producing slightly funnel-shaped brochi (Plate I, 9). Occurrence: I-14-1, I-14-2.

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Remarks: This pollen type matches very well in size, apertural configuration and ectexine ornamentation the extant Flueggea and to lesser extant Margaritaria Linné taxa depicted in Köhler (1967, plate 1, figs. 1-9, LM images; in particular Flueggea suffruticosa (Pallas) Baillon), in Sagun and van der Ham (2003, figs. 2 a-e and f, LM and SEM images) and in Webster (1984, in particular Flueggea verrucosa (Thunberg) Webster figs. E, F, SEM images,). Comparable lower and middle Eocene Flueggea-types from the PETM section in England (Brixton-type), the EECO in Austria (Krappfeld-type), and mid-Eocene from Germany (Borken-type) have been described in Hofmann et al. (2015b) and Hofmann and Gregor (2018). The Flueggea taxon from Hainan differs from the two European Flueggea-types by having a less prominent tectate margo. Habitat today: Generally, Flueggea taxa are deciduous shrubs that thrive under seasonal conditions

ACCEPTED MANUSCRIPT and are very adaptable to various climates. Flueggea verrucosa (SE Cape Province, South Africa) grows in Cfa, Cfb, Cwa, and BWh climate zones. Also the east Asian (China, Korea, Japan, Russian Far East) Flueggea suffruticosa thrives under various, but generally more humid conditions: Am, Aw, Cfa, Cfb, Cwa, Cwb, Cwc, Bsk, Dwa, Dwb, and Dwc; the latter three are snow climates.

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Phyllanthus Linné Phyllanthus subgenus Eriococcus (Hasskarl) Croizat et Metcalf/Isogladus G.L. Webster

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Phyllanthus subgenus Eriococcus/Isocladus-type sp. 1 (Plate I, 11-12)

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Description: LM: Pantoporate (more than 10 pores), oblate to spheroidal pollen grain, circular to elliptic in compressed fossilized state (N = 7, Plate I, 10); diameters ranging from 32, 1 to 45.3 µm;

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pore sizes ca. 3.5 to 4.5 µm; wall thickness ranging from 1.9 to 2.2 µm with the sexine thicker than

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nexine; reticulate. SEM: The ectexine is reticulate, heterobrochate with circular to slightly angular brochi, brochi sizes between 0.8 to 3.7 µm (Plate I, 11, 12); muri are shallow, ca. 0.5 to 0.8 µm

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wide and often but not always densely covered with micro-gemmae of ca. of ca. 0.1 to 0.15 µm in size; duplicolumellate, columellae are 1 to 1.2 µm high and wider than the muri, columellae are

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regularly fused and perforated producing sometimes funned-shaped brochi that mimick a fragmentary bireticulation (Plate I, 12); visible footlayer sometimes perforated, also.

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Occurrence: I-14-1, I-14-3, III-2-2.

Remarks: This pollen type is reminiscent of the extant pantoporate, reticulate palaeotropical Phyllanthus taxa of the subgenus Eriococcus (Hasskarl) Croizat et Metcalf and section Ceramanthus (Hasskarl) Baillon of subgenus Isocladus G.L. Webster in Webster and Carpenter (2008, figs. 13-16; e.g., Phyllanthus kinabaluicus Airy Shaw and Phyllanthus ruber (Lour.) Sprengler). The sections Eriococcus, Eriococcodes and Ceramanthus have been combined as a “Phyllanthus buxifolius type” by Punt (1980, Guinea taxa) and Chen et al. (2009, Philippine taxa). However, our fossil taxon does not match most of the extant investigated grains in size (20 to 30 µm), except some taxa of the section Ceramanthus that have sizes up to 47 µm. The (mimicked) bireticulation of our pollen taxon can be found in other Phyllanthus pollen; for example, in the

ACCEPTED MANUSCRIPT tricolporate Phyllanthus of the “phillyreifolius group”(amongst others, comprising subgenera Isocladus, Phyllocladus G.L. Webster and Urinaria G.L. Webster) that have been investigated by Bor (1979). The fragmentary bireticulation (wide fused, perforated columellae) might be a precursor of the free-standing colummelae (“granulae”) of the present-day pantoporate Phyllanthus taxa. In the fossil record of China, the name of this pollen type is Retimultiporopollenites

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P. subgenus Eriococcus/Isocladus-type sp. 2 (Plate II, 1-3)

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qionbeiensis Li and Sun and has been depicted in Lei et al. (1992, plate 6, fig. 23).

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Description LM: Pantoporate (more than10 pores), oblate to spheroidal pollen grain, circular to elliptic in compressed fossilized state (Plate II, 1); diameters ranging from 23.8 to 30.1 µm (N = 2);

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pore sizes ca. 2.5 to 3.5 µm; wall thickness ca. 1.5 to 1.6 µm with the sexine as thick as to slightly

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thicker than nexine; reticulate. SEM: The ectexine is reticulate, heterobrochate with circular to elliptic brochi with sizes between 1 to 2.5 µm and scattered foveolae (Plate II, 2); muri are flat and

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smooth (Plate II, 2, 3), ca. 1 to 1.5 µm wide and duplicolumellate; columellae are ca. 1 µm high, densely packed and often fused and much wider than the muri thus producing funnel shaped brochi

Occurrence: I-13-1.

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(Plate II, 3) simulating a bireticulation.

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Remarks: Our fossil pollen grains show, in particular, similarities with the extant Phyllanthus leptocladus Bentham (subgenus Eriococcus) and Phyllanthus chekiangensis Croizat et Metcalf (subgenus Isocladus) depicted in Zhongxin (2003, plate 43, fig. 5; plate 42, figs. 5-6, SEM images); the latter has more pori.

Habitat today: Phyllanthus is a huge genus, with ca. 1269 taxa (Kathriarachchi et al., 2006); the subgenera Eriococcus and Isocladus inhabit the tropics and warm temperate climates. For example, Phyllanthus leptocladus and Phyllanthus chekiangensis are shrub-like plants that occur in SE China today and grow in Cwa and Cwb climate zones, whereas Phyllanthus ruber and Phyllanthus kinabaluicus thrive in more tropical Af, Am and As climate zones.

ACCEPTED MANUSCRIPT Fagales Engler Fagaceae Dumortier Fagoideae K. Koch Fagus Linné Fagus-type (Plate II, 4-6)

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Description LM: Tricolporate, prolate pollen grain, elliptic to slightly rhombic in equatorial outline with protruding apertural regions in compressed fossilized state (N = 3; Plate II, 4); polar diameter

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ranging from 21.6 to 23.3 µm and equatorial diameter from 19.6 to 19.8 µm in length, colpus length

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ca. 16.6 to 18.9 µm reaching into the polar areas, endoapertures more-or-less rectangular to slightly circular (Plate II, 4) ca. 1.7 to 2 µm high and 3.8 to 4.5 µm wide; wall thickness ca. 0.9 to 1.2 µm

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with the sexine slightly thicker than nexine, the latter thickened around the endoapertures and

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thinning towards the poles; scabrate. SEM: The ectexine is micro-rugulate, perforate (Plate II, 5), whereas the micro-rugulae are arranged in a loose criss-cross pattern with some micro-rugulae

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sticking conspicuously outwards (Plate II, 6), micro-rugulae are between 0.2 to 0.7 µm long and ca. 0.1 µm wide.

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Occurrence: I-14-1, I-14-2, III-2-2

Remarks: This pollen taxon is very similar in size, ectexine ornamentation, the long colpi and the

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rectangular endoaperture to pollen of Fagus “subgenus Engleriana” sensu Shen (1992; see Renner et al., 2016) in Denk (2003, plate 3, figs. 1-19, SEM images, e.g., Fagus engleriana Seemen, Fagus japonica Maximovicz), in Praglowski (1982, fig. 3a-c, g, SEM and TEM images) and to pollen that are associated with lower Eocene fruits and leaves of Fagus langevinii Manchester et Dillhoff from British Columbia (Manchester and Dillhoff, 2004, fig. 4A-D, LM and SEM images; please note that the original mid-Eocene age estimation for this taxon has been corrected: see Denk and Dillhoff, 2005). It also resembles the even older Palaeocene Fagus sp. pollen grain from Agatdalen valley on Greenland in Grimsson et al. (2016, plate 3, figs. 10-12, LM and SEM images), and, to a much lesser extant, the quite variable middle Eocene Fagus pollen grains in Grimsson et al. (2015, figs. 9 and 10, LM and SEM images) from the Hareøen Formation on West Greenland: These are much

ACCEPTED MANUSCRIPT larger than our taxon and generally lack the perforations. Our Fagus-type pollen is much smaller and does not look at all like Faguspollenites longicolpus Ke et Shi reported from the Changchang Formation by Lei et al. (1992, plate 5, fig. 47, LM image). Fagus pollen has been reported from the contemporaneous Youganwo Formation of the Moaming basin (South China) by Aleksandrova et al. (2015), but no images were provided and, therefore, we cannot be sure if this is the same taxon.

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Habitat today: Taxa of Fagus “subgenus Engleriana” live today on the northern hemisphere in

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temperate to warm temperate, humid climates such as in Cfa, Cfb, Cwa and Cwb climate zones.

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Juglandaceae de Candolle ex. Perleb Juglandioideae Eaton

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Juglans Linné

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Juglans-type (Plate II, 7-9)

Description LM: Pantoporate (seven to nine pores), heteropolar, spheroidal to oblate pollen grain,

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circular to slightly angular in fossilized compressed state (Plate II, 7); diameter ranges between 22.1 to 27.3 µm; pore diameter ranges from 1.2 to 1.4 µm, with the distal pole displaying one pore (N =

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5); wall thickness ca. 1.2 to 1.3 µm; scabrate. SEM: The ectexine is regularly and densely covered with minute micro-gemmae/echini (Plate II, 8, 9) of ca. 0.25 to 0.3 µm in diameter, micro-

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gemmate/-echinate ornamentation is less pronounced around the pori (Plate II, 9). Occurrence: I-14-1, I-14-3, III-2-2 Remarks: This pollen taxon looks like Juglans, and particularly like Juglans mandshurica Maximowicz and Juglans cathayensis Dode (= synonym of Juglans mandshurica) of Juglans section Cardiocaryon Dode, depicted in Fujiki et al. (2005, plate 57, figs. 1-6, LM and SEM images as J. cathayensis), in Wei (2003, plate 83, figs. 3-4 as J. cathayensis), in Li et al. (2011, page 506 as J. mandshurica), in Miyoshi et al. (2011, plate 16, figs. 1-3 as J. mandshurica) and in Stone and Broome (1975, fig. 8f as J. mandshurica). It also resembles Juglans ailantifolia Maximowicz section Cardiocaryon in Stone and Broome (1975, fig. 1k, and fig. 8e, LM and SEM images). The taxa of section Cardiocaryon differ from isopolar Juglans regia Linné (section Juglans), Juglans

ACCEPTED MANUSCRIPT sigillata Dode, Juglans californica, Juglans major and Juglans mollis (section Rhysocaryon) by generally having less pores (see Fujiki et al., 2005, plate 58, figs. 1-6 and plate 59, figs 1-6; Stone and Broome, 1975 fig. 8 and table 2, respectively), and by the presence of much fewer pores (only one or two pores) on the distal pole. However, that specific heteropolar pore arrangement also sometimes can be seen on Pterocarya rhoifolia Wilson (Juglandaceae; Miyoshi et al., 2011, plate

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16, figs. 5-7 and Stone and Broome, 1975, fig.6e) and Pterocarya insignis Rheder et E.H. Wilson (Fujiki et al. (2005, plate 63, figs. 1-6). But, generally, the two Pterocarya taxa have four to eight

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pores in comparison to the taxa of section Cardiocaryon, which have five to 11 pores (data from

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Stone and Broome, 1975, table 2). The much higher percentages of heteropolar grains (up to 97 %, Stone and Broome, 1975, pollen key) in section Cardiocaryon pollen differentiate them from pollen

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of section Trachycaryon (e.g., Juglans cinera) where this phenomenen is much rarer (10-35 %,

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Stone and Broome, 1975, pollen key). Additionally, section Trachycaryon pollen have a more pronounced angular amb. Consequently, we assume that our Juglans-type pollen belongs more into

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section Cardiocaryon than into Trachycaryon or Pterocarya rhoifolia and P. insignis. Our pollen type probably could be the same as Juglanspollenites rotundus Ke et Shi from the Changchang

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Formation depicted by Lei et al. (1992, plate, 5, fig. 9). Habitat: Juglans is a deciduous tree growing in the temperate warm to subtropical realm in the

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Americas, SE Europe and eastern Asia to Japan (Manning, 1978). The taxa of Juglans section Cardiocaryon do occur in warm to temperate mixed forests on mountains from SE China to Taiwan, North China, Japan, Korea and to the Russian Far East (Aradhya et al., 2007, fig. 1 distribution map), in the Cfa, Cfb,, Cwa, Cwb, Dwa, and Dwb climate zones.

Myrtales Reichenbach Lythraceae J. St.-Hilaire. Lagerstroemia Linné Lagerstroemia-type (Plate II, 10-12, Plate III, 1-3) Description LM: Tricolporate (with three extra pseudocolpi), subprolate pollen grain, circular to

ACCEPTED MANUSCRIPT slightly rhombic in equatorial outline in fossilized and compressed state (Plate II, 10, Plate III, 1; N = 3), polar axes of 29 to 35.5 µm and equatorial axes of 24.1 to 26.5 µm length; colpi between 19.2 and 21.6 µm length, endopori circular (Plate II, 10, Plate III, 1) ca. 1.2 µm in diameter, but faintly visible; pseudocolpi weakly developed; wall thickness at the polar areas ca. 2.1 to 2.6 µm and in the mesocolpium 1.6 to 2.2 µm with the sexine generally thicker than nexine, particularly at the polar

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areas; verrucate. SEM: The ectexine is tectate, verrucate to rugulate (Plate II, 11, Plate III, 2), sometimes perforations on rugulae and verrucae are present (Plate II, 11, 12, Plate III, 2, 3), the

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rugulate- verrucate pattern is coarser on the ridge-like mesocolpium areas (meridional ridges, Plate

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III, 3) in between pseudocolpi and in the polar areas, polar areas can be smooth and faintly perforated, the tectum can be locally dotted with minute micro-gemmae; colpi have rounded ends,

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colpus membrane is micro-verrucate (Plate II, 12).

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Occurrence: I-14-1, I-14-3, III-2-2.

Remarks: This pollen taxon is very reminiscent of pollen of extant Chinese Lagerstroemia taxa

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depicted in Liu et al. (2008, fig. 5 A-S, Lagerstroemia limii Merrill and Lagerstroemia subcostata Koehne from antepetalous stamen), in Kim et al. (1994, Lagerstroemia limii: fig. 5 G, H;

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Lagerstroemia subcostata: fig. 5 E, F), and in Miyoshi (2011, Lagerstroemia subcostata: plate 166, fig. 9-12). These two extant taxa have pollen that resemble very much the Miocene pollen taxon

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Lagerstroemia cathayensis Liu, Zetter, Ferguson et Zou in Liu et al. (2008, fig. 3 A-R). Habitat: Lagerstroemia subcostata and Lagerstroemia limii are deciduous shrubs and trees present in China, Taiwan, the northern Philippines and Japan in the Cfa, Cfb, Cwa, Cwb, Aw and Am climate zones.

Malvales Berchtold et J. Presl Malvaceae Jussieu Tilioideae Arnott Craigia W.W. Smith et W.E. Evans Craigia-type (Plate III, 4-6)

ACCEPTED MANUSCRIPT Description LM: Tricolporate (brevicolporate), oblate pollen grain in fossilized compressed state, in polar view more-or-less circular to slightly angular (Plate III, 4); equatorial diameter 24.6 to 26µm; slightly thickened u-shaped aperture regions (Plate III, 4); wall thickness ca. 1.1 µm with the sexine as thick as nexine; scabrate. SEM; The ectexine is evenly micro-reticulate, perforate (Plate III, 5, 6), with circular to elliptic brochi of ca. 0.5 µm diameter and smaller. The muri display a faint but

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characteristic striate pattern along the muri and around brochi (Plate III, 6). Occurrence: I-14-1, I-14-3, III-2-2.

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Remarks: This is a typical habitus for Eocene Craigia pollen and resembles Craigia sp. 1 from

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Paleocene-Eocene Thermal Maximum successions (PETM) at Brixton (London area) and Cobham (Kent) in England (Bleidt, 2016, figs. 5 a-c and 23 a-d, respectively), from St. Pankraz in Austria

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et Manchester in Zetter et al. (2002, fig. 1).

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(Hofmann et al., 2011, plate 7, figs. 4-6), and Miocene age Craigia bronni (Unger) Kvaček, Bužek

Habitat: The extant species, Craigia yunnanensis W.W. Smith et W.E. Evans, occurs in warm

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temperate areas of China and northern Vietnam in the Cfa, Cwa, Cwb, and Dwc climate zones.

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Mortoniodendron Standley et Steyermark

Mortoniodendron-type sp.1 (Plate III, 7-9)

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Description LM: Tricolporate (brevicolporate), oblate pollen grain in fossilized compressed state, in polar view more-or-less circular (Plate III, 7), equatorial diameter 27.2 to 28.5 µm; with conspicuously thickened c-shaped apertural areas (Plate III, 7), wall thickness ca. 0.8 to 1.1 µm; reticulate. SEM: The ectexine is semitectate, reticulate with rounded to angular brochi (Plate III, 8, 9) of 1 to 1.8 µm in diameter; muri are smooth and slightly keeled and ca. 0.25 to 0.3 µm wide, lumina are densely filled with sometimes fused and sometimes free-standing columellae (Plate III, 9), that produce a rudimentary bireticulation; the ectexine pattern does not change towards the ectoapertures (Plate III, 8). Occurrence: I-14-1, I-14-3, III-2-2. Remarks: This pollen taxon resembles Mortoniodendron costaricense Standley et L.O. Williams (=

ACCEPTED MANUSCRIPT synonym of Mortoniodendron guatemaltense Standley et Steyermark) depicted in Perveen et al. (2004, fig. 17 a-f, SEM images) in size, apertural configuration, ectexine pattern and in the feature that the ectexine pattern does not change at the ectoapertures.

Mortoniodendron-type sp. 2 (Plate III, 10-12)

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Description LM: Tricolporate (brevicolporate), oblate pollen grain in fossilized compressed state, in polar view circular to slightly triangular (Plate III, 10), equatorial diameter 24 to 24.4 µm; slightly

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thickened wide c-shaped apertural areas (Plate III, 10), wall thickness 0.9 to 1.1 µm; reticula te.

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SEM: The ectexine is semitectate, micro-reticulate, heterobrochate with circular to elliptic brochi (Plate III, 11, 12) of 0.35 to 0.8 µm in diameter; muri are smooth and slightly keeled and ca. 0.15 to

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0.25 µm wide; lumina are densely filled with few, mostly fused free-standing columellae that

the ectoapertures (Plate III, 11).

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Occurrence: I-14-1, I-14-3, III-2-2.

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produce a rudimentary bireticulation (Plate III, 12); the ectexine pattern does not change towards

Remarks: This pollen taxon resembles in size and apertural configuration to some degree

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Mortoniodendron costaricense depicted in Perveen et al. (2004, fig. 17 a-f) in the ectexine pattern

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and in the feature that the ectexine pattern does not get more tectate at the ectoapertures.

Remarks to the two Mortoniodendron-types: Fossil pollen also affiliable with Mortoniodendron have been found from the lowermost Eocene strata at Brixton, England (unpublished LM and SEM images by Hofmann), the Krappfeld area in Carinthia (Austria, Hofmann and Zetter 2001, plate 3, figs.15-17, ”Sterculiaceae gen. indet.”) and in the mid-Eocene Messel locality, Germany, (Grimsson et al., 2017, fig. 5 K-Q, LM and SEM images). Fossil pollen that may represent Mortoniodendron have been described and depicted by Krutzsch (2004, drawings and LM images, fig. 2d, fig. 6, 1-14, plate 3 fig. E881, plate 4) from the Paleogene in Germany and by Graham (1979, page 572, fig. 2, 3, respectively, LM images) from middle and upper Miocene sediments of Central America. Habitat today: The small genus Mortoniodendron comprises 18 species of shrubs and high forest

ACCEPTED MANUSCRIPT trees that occur from SE Mexico to western Colombia (Solis-Moreno et al., 2013) in tropical to subtropical areas of the Af, Am, Aw and Cwa, Cwb climate zones.

Dipterocarpaceae Blume Dipterocarpoideae Burnett

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Dryobalanops C.F. Gaertner cf. Dryobalanops-type (Plate IV, 1-3)

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Description LM: Tricolpate, prolate pollen grain, in equatorial view elliptic (compressed, fossilized

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state; Plate IV, 1), polar axes 28.9 to 31.1 µm and equatorial axes 20.5 to 21.2 µm (N = 2), slit-like colpi (Plate IV, 1) that are 23.5 to 26.4 µm long; wall thickness 1.3 to 1.6 µm with the sexine much

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thicker than nexine; reticulate. SEM: The ectexine is semitectate, reticulate, heterobrochate (Plate

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IV, 2) with circular, elongated circular and slightly angular brochi ranging from 0.5 to 2 µm in diameter (Plate IV, 2); muri are slightly crenulated with regular grooves transverse perpendicularly

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the muri (Plate IV, 3); columellae often are fused (like “columellar walls”) and are wider than the muri (Plate IV, 3; muri width 0.7 to 1 µm). Grooves on the muri seem to indicate the separation of

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columellae; visible footlayer is smooth (Plate IV, 3). Occurrence: I-14-1, III-2-2.

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Remarks: This pollen taxon resembles closely Dipterocarpaceae pollen and matches in size, apertural configuration and, to some degree, the ectexine pattern (grooves on muri, fused columellae) of extant Dryobalanops taxa described and depicted in Maury et al. (1975, plate 6, figs. 2, 3, all SEM images), despite the fact that the brochi of our fossil taxon are larger. The LM images resemble very slightly the considerably larger pollen of Albertopollenites kutchensis Mandal et Rao in (1) Mandal and Rao 2001, plate 4, figs. 3-5 from southern Kutch of middle to late Eocene age and (2) from the lower part of the lower Eocene Vastan lignite section in western India depicted in Dutta et al. (2011, plate 1 fig. D, E, LM images). However, exactly the same LM image in Dutta et al. (2011) has been depicted by Rao et al. (2013, plate 3, fig. 19) under the name Retitrescolpites sp. that apparently came from the top of the Vastan lignite section. In Dutta et al. (2011),

ACCEPTED MANUSCRIPT Albertopollenites kutchensis has been affiliated with extant Dipterocarpus indicus (Dutta et al., 2011, plate 1, fig. H, I, LM images), together with other fossil taxa e.g., Foveotricolpites alveolatus Mandal et Rao and Dipterocarpuspollenites retipilatus Kar (Dutta et al., 2011, plate 1, figs. F, G and A-C, respectively, whereas fig. A looks very different from fig. B and C and most likely represents a different fossil taxon). However, none of the images of the three fossil taxa mentioned

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above actually resemble the LM images of extant Dipterocarpus indicus (Dutta et al., 2011, plate 1,

(2001, plate 1 fig. 4) from much younger Pliocene strata does.

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fig. H, I). On the other hand, the LM images of Dipterocarpus retipilatus Kar in Mandal and Rao

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Habitat today: Dryobalanops is an evergreen forest tree in the tropical realm (Malaysia, Borneo,

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Sumatra; Mabberley, 1997, Maury-Lechon and Curtet, 1998) of the Af and Am climate zones.

cf. Dipterocarpus-type (Plate IV, 4-6)

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Dipterocarpus C.F. Gaertner

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Description LM: Tri- to tetracolpate pollen grain, can be fossilized in two ways (N= 8): (1) Perpendicular to the polar axis, then the pollen is oblate with a trilobate (gaping colpi) to circular

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outline in polar view and equatorial diameters ranging between 22.5 and 35.3 µm. (2) Parallel to the polar axis then the pollen is prolate with an elongated elliptical to slightly rhombic outline in

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equatorial view (Plate IV, 4), with polar axis ranging from 30.2 to 35.5 µm and equatorial axis from 19.8 to 26.3 µm; slit-like colpi are 22.1 to 25.2 µm long (Plate IV, 4, 5); wall thickness ca. 1.7 to 1.9 µm with the sexine much thicker than nexine; perforate to micro-reticulate. SEM: The ectexine is semitectate, micro-reticulate, more or less homobrochate with slightly angular to circular and elliptic to slit-like brochi (Plate IV, 5) ranging from 0.2 to 0.8 µm in diameter; muri are sometimes keeled and undulating vertically, displaying occasionally micro-echini and randomly striae that transverse the muri (Plate IV, 6); columellae sometimes visible, and probably not fused; colpus membrane, when present is micro-verrucate to micro-rugulate (N = 2). Occurrence. I-14-1, I-14-3, III-2-2. Remarks: The LM images, apertural configuration, the ectexine pattern under SEM, and the colpus

ACCEPTED MANUSCRIPT membrane ornamentation matches very well Dipterocarpus taxa depicted in Maury et al. (1975, plate 1 to 3, SEM and LM images). However, our fossil pollen grains are generally slightly smaller and occasionally tetracolpate; up to now, Maury et al. (1975) observed tetracolpate pollen grains only in extant Hopea and Shorea, but not yet in Dipterocarpus. The LM images of the oblately preserved specimen are slightly reminiscent of LM images of Dipterocarpuspollenites retipilatus

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Kar in Mandal and Rao (2001, plate 1, fig. 4 but not plate 2, fig. 13). Habitat today: Dipterocarpus is a SE Asian tree living in seasonal and aseasonal tropical areas

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(Maury-Lechon and Curtet, 1998) of the Af, Am and Aw climate zones.

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Remarks to the two Dipterocarpaceae: Maury et al. (1975, fig. 1, schematic reconstruction from TEM and SEM sections) demonstrated that the outer layer of the pollen wall of some Dipterocarpus

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and Dryobalanops is not reticulate but somehow convolute, thus only mimicking a reticulate

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pattern. We are not able to see that on our fossil pollen specimen because we have no TEM

Cornales Link

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Cornaceae Berchtold et J. Presl

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sections.

Cornus Linné

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Cornus-type (Plate IV, 7-9)

Description LM: Tricolporate, prolate pollen grain, elliptic to slightly rhombic in equatorial view in compressed fossilized state with protruding apertural regions (Plate IV, 7), polar axis 41.2 µm and equatorial axis 33.2 µm, colpi ca. 36.2 µm long, endoapertures lalongate 1.8 µm high and 2.6 µm wide, costae visible (Plate IV, 7); scabrate. SEM: The ectexine is tectate, perforate and in the mesocolpium areas irregularly fossulate and micro-echinate (Plate IV, 8, 9), whereas the microechini sit on broad based verrucae (Plate IV, 9); colpi ends are rounded (Plate IV, 8). Occurrence: I-14-3 Remarks: This pollen taxon resembles well Cornus alba Linné in Li et al. (2011, plate 355, figs. 14) and somewhat Cornus sanguinea Linné (own material; both subgenus Kraniopsis Rafinesque-

ACCEPTED MANUSCRIPT Schmaltz), despite the fact that the fossil pollen is smaller. To a lesser extent, it resembles Swida controversa (=Cornus controversa Hemsley ex. Prain of subgenus Mesomora RafinesqueSchmaltz) in Miyoshi et al., 2001, plate 179, figs. 13-16) and Li et al. (2011, plate 353, figs. 1-4), because our taxon displays more conspicuous perforations and a less pronounced fossulateverrucate/echinate pattern in the mesocolpium areas and smoother polar areas.

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Habitat today: Cornus is a northern hemisphere genus, comprising mostly woody shrubs; Cornus alba is a temperate shrub that occurs from Russia to North Korea, Cornus sanguinea is a temperate

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shrub occurring from Europe to western Asia. Cornus controversa is a small tree to large shrub in

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Csa, Csb, Dfa, Dfb, Dwa, Dwb and Dwc climate zones.

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E. Asia (Himalaya, China and Japan). All need moist soils and thrive in Cfa, Cfb, Cfc, Cwa, Cwb,

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Nyssaceae Martius Nyssa Gronovius ex. Linné

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Nyssa-type (Plate IV, 10-12, Plate V, 1-3)

Description LM: Tricolporate, subprolate to spheroidal pollen grain, elliptic rhombic to circular

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rhombic in equatorial view or triangular to circular in polar view in compressed fossilized state with protruding apertures (Plate IV, 10, Plate V, 1; N = 5); polar axes 21.1 to 26.6 µm and equatorial

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axes 19.6 to 26.7 µm long; colpi 16.8 to 23.8 µm long, endoapertures lalongate, rectangular 1.6 to 1.8 µm high and 3.2 to 4 µm wide, costae visible (Plate IV, 10, Plate V, 1); wall thickness ca. 0.9 to 1.1 µm with the sexine thicker than nexine; scabrate. SEM: The ectexine is tectate, irregularly micro-rugulate to micro-verrucate, fossulate, perforate, the margos are tectate, faintly perforate (Plate IV, 11, Plate V, 2); micro-rugulae are unevenly shaped ca. 0.5 to 0.7 µm wide and up to 1.3 µm long and bordered by fossulae (Plate IV, 12, Plate V, 3). Occurrence: I-14-1, I-14-3, III-2-1, III-2-2. Remarks: This pollen taxon is reminiscent in size, apertural arrangement and ectexine ornamentation to extant Nyssa taxa and, in particular, to Nyssa sinensis Oliver depicted in Göschl (2008, plate 13-15, LM and SEM images), which also has a tectate margo, but more pronounced

ACCEPTED MANUSCRIPT perforations in the polar and mesocolpium areas. A middle Eocene Nyssa sp. taxon from Germany depicted in Grimsson et al. (2017, fig. 2 B-J) resembles our Nyssa-type very well, in contrast to a middle Eocene Nyssa sp. pollen from the Princeton Chert (Canada), which is characterized by very conspicuous perforations and foveolae (Göschl, 2008, plates 26, 27). Younger taxa from the Miocene of Germany and Austria show little similarities in the ectexine ornamentation (Göschl,

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2008, plate 28-31, LM and SEM images). Habitat: Nyssa is a flood tolerant disjunctly distributed taxon in North and Central America and

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Asia. Nyssa sinensis (molecular and morphological data suggested including N. shangszeenis

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(W.W. Sm) Airy Shaw, N. shweliensis W.P. Fang et Soong and N. wenshannensis W.P. Fang et Soong into N. sinensis, Wang et al., 2012) occurs from South China to Vietnam in wet mixed

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forests and near streams in Cfa, Cwa, and Cwb climate zones.

Ericales Dumortier

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Symplocaceae Desfontaines Symplocos Jacquin

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Symplocos-type sp. 1 (Plate V, 4-6 )

Description LM: Tricolporate (brevicolporate) oblate pollen grain, triangular with truncated apices

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in polar view, ambs are straight in compressed fossilized state (Plate V, 4); equatorial diameter 27.2 to 29.3 µm, vestibuli pori faintly visible (Plate V, 4); wall thickness ca. 1.2 to 1.3 µm with the sexine as thick as nexine; reticulate. SEM: The ectexine is semitectate, rugo-reticulate and perforate (resembling a bireticulate pattern), with slightly angular polyform brochi (Plate V, 5, 6) ranging from ca. 0.4 to 1.3 µm in diameter; muri are shallow, smooth, occasionally perforated (Plate V, 6) and ca. 0.8 to 1.5 µm wide. Occurrence: I-14-1, I-14-3, III-2-1.

Symplocos-type sp. 2 (Plate V, 7-9) Description LM: Tricolporate (brevicolporate) oblate pollen grain, triangular with slightly truncated

ACCEPTED MANUSCRIPT apices in polar view, ambs are slightly convex to straight in compressed fossilized state (Plate V, 7); equatorial diameter 24.6 to 25.4 µm, vestibuli pori fainlty visible (Plate V, 7); wall thickness ca. 0.9 to 1.1 µm with the sexine as thick as to slightly thicker than nexine; reticulate. SEM: The ectexine is semitectate, reticulate to faintly rugo-reticulate (resembling a faint bireticulate pattern; Plate V, 8, 9), with slightly polyform brochi ranging from ca. 0.3 to 1.1 µm in diameter; muri are shallow,

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smooth (Plate V, 8, 9) and ca. 0.7 to 1 µm wide (unfortunately the fossil is partly covered by glycerine).

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Occurrence: I-14-1, I-14-3.

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Remarks to Symplocos sp.1 and sp. 2: The LM images of these two pollen taxa look like many taxa of Symplocos. However, the SEM images of the rugo-reticulated (described as suprareticulate by

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Wang et al., 2004) ectexine show similarities to Symplocos chinensis Druce and Symplocos

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paniculata (Thunberg) Miquel of subgenus Palura sensu Fritsch et al. (2008), both depicted in Gruber (1996, plate 4, figs. 8, 11, 12 and plate 6, figs. 2, 5, 6, respectively, LM and SEM images;

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Symplocos chinensis might be a synonym for Symplocos paniculata). The material examined resembles SEM images of Symplocos chinensis in Miyoshi et al. (2011, plate 204, figs. 1-4) and in

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Wei (2003, plate 95, figs. 1-7), but the modern taxon has slightly more concave ambs, slightly narrower muri and no perforations in the muri. From the Changchang Formation, comparable

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Symplocos pollen grains have been reported as Symplocoipollenites latiporus (Thomson et Pflug) Zheng in Lei et al. (1992, plate 7, fig. 33, LM image).

Symplocos-type sp. 3 (Plate V, 10-12) Description LM: Tricolporate (brevicolporate) oblate pollen grain, triangular to slightly trilobate with slightly truncated apices in polar view, ambs are slightly concave in compressed fossilized state (Plate V, 10); equatorial diameter 24.3 to 25.9 µm, vestibuli pori visible (Plate V, 10); wall thickness ca. 1.5 to 1.6 µm with the sexine as thick as to thicker than nexine; rugulate. SEM: The ectexine is tectate, rugulate, fossulate (Plate V, 11, 12), whereas the rugulate-fossulate pattern is opening up into a reticulate pattern in the polar and mesocolpium areas (Plate V, 12); rugulae

ACCEPTED MANUSCRIPT irregularly shaped ranging in size from ca. 0.9 to 1.5 µm in width and ca. 1.1 to 1.8 µm in length; rugulae are smooth (Plate V, 12). Occurrence: I-14-1. Remarks: The LM images match well Symplocos taxa and in particular the LM images Symplocos chinensis and Symplocos paniculata in Gruber (1996, plate 4, fig. 7, and plate 6, fig. 1) and to a

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lesser extent the SEM images of the more rugulate-fossulate ectexine (reticulate only in the mesocoplium areas) of Symplocos paniculata in Gruber (1996, plate 6, fig. 2). The LM image also

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displays some slight reminiscences to Symplocos prunifolia Siebold et Zuccarini in Gruber (1996,

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plate 13, figs. 1, 5) and SEM images in Miyoshi et al. (2011, plate 204, figs. 5-7). From the Changchang Formation, a comparable Symplocos pollen grain has been reported as

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Symplocoipollenites vestibulum R. Potonié in Lei et al. (1992, plate 7, fig. 34, LM image).

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Habitat today: Symplocos paniculata (= Symplocus chinesis) is a very adaptable deciduous species occurring from India to Japan (it is grown successfully in North America and Europe as a garden

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plant) thriving in Cfa and Cfb, Dwa and Dwb climate zones. The evergreen Symplocos prunifolia occurs in warm temperate to subtropical areas of Japan and South Korea (Cfa and Cwa climate

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Icacinales van Tieghem

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zones.

Icacinaceae Miers

“Icacina group” sensu Kårehed 2001 Mappia Jacquin/Nothapodytes Blume Mappia/Nothapodytes-type (Plate VI, 1-3) Description LM: Tricolpate, subprolate pollen grain, in equatorial view pear-shaped because of compressed fossilized state (Plate VI, 1); polar axis 30.6 µm and equatorial axis 20.5 µm long, colpi ca. 22µm long (N = 1), wall thickness ca. 1 µm the sexine is probably as thick as nexine; echinate. SEM: The ectexine is tectate, echinate and perforate, the echini are angular (more-or-less pyramidal; Plate VI, 2, 3) and ca. 1 to 1.3 µm long, perforations are regularly distributed (ca. 10 per

ACCEPTED MANUSCRIPT square µm, Plate VI, 3), the densely echinate colpus membrane is recognizable through the opening of the colpus (Plate VI, 3). Occurrence: I-14-1 Remarks: This pollen taxon resembles very well LM and SEM images of two Icacinaceae genera: Mappia in Lobreau-Callen (1972, plate 12, fig. 4: LM of Mappia mexicana Robins et Greenman;

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1973, plate 6, figs. 4, 5: SEM of Mappia racemosa Jacquin) and Nothapodytes in Lobreau-Callen (1972, plate 12, figs. 6, 7: LM of Nothapodytes foetida (Wight) Sleumer and N. pittosporides

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(Oliver) Sleumer, respectively) and in Vasanthy et al. (1993, fig. 13-15: SEM of Nothapodytes

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foetida = synonym of Nothapodytes nimmoniana (J. Graham) Mabberley).

Habitat today: Mappia mexicana and M. racemosa are known from SE Mexico, Central America

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and the West Indies (Angulo et al., 2013, distribution map; Potgieter and Duno, 2016). Both inhabit

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the Af, Am, Aw and As climate zones. Nothapodytes occurs in southern Asia, whereas N. pittosporides lives in China in Cfa, Cwa and Cwb climate zones, and N. nimmoniana has a much

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wider range: Taiwan, Philippines, southern Japan, Thailand, Cambodia, Myanmar, India and Sri

Iodes Blume

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Lanka growing in Af, Am, Aw, As, Cfa, Cwa, and Cwb climate zones.

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Iodes-type sp. 1 (Plate VI, 4-6)

Description LM: Triporate (not very well visible pores), oblate pollen grain, more or less circular in fossilized compressed state (Plate VI, 4), diameters range from 19.8 to 24.3 µm (N= 3); wall thickness ca. 1.2 µm with the sexine as thick as nexine; echinate. SEM: The ectexine is tectate, perforate with regularly spaced, smooth, supratectal echini with very broad basis (1.3 to 1.8 µm wide, Plate VI, 5) that taper quickly into thin curved echini (Plate, VI 6) of ca. 1.7 to 2.1 µm length. Occurrence: I-14-1, I-14-3. Remarks: LM and SEM images of this pollen resembles the description and LM images of Iodes taxa in Lobreau-Callen (1972, plate 16, figs. 34-37) and also to a certain degree SEM images in Lobreau-Callen (1973, page 62, plate 2, figs. 8, 9, 10, in particular Iodes africana Welwitsch ex

ACCEPTED MANUSCRIPT Oliver and I. globulifera H. Perrier; both have the typical tapering echini). This Iodes-type pollen could be the fossil Iodes that has been affiliated with Iodes cf cirrhosa Turczaninow by Lei et al. (1992, plate 6, fig. 15, LM image). Habitat today: Iodes is a tropical liana genus from Africa, Madagascar and Australasia (Potgieter and Duno, 2016). However, Iodes africana occurs only in tropical forests in Africa in Af, Am, Aw

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and As climate zones, whereas Iodes globulifera is endemic in NW Madagascar and occurs in Am

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and Aw climate zones.

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Iodes-type sp. 2 (Plate VI, 7-9)

Description LM: Porate (not very well visible pore on the right), oblate pollen grain, more or less

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circular to elliptic in fossilized compressed state (Plate VI, 7), diameters range from15.9 to 19.5

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µm; wall thickness ca. 0.9-1 µm; echinate. SEM: The ectexine is tectate, perforate, micro-verrucate (ca. 0.3 µm in diameter) with regularly spaced, smooth, supratectal echini with very broad basese

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(1.8 to 2 µm wide, Plate VI, 8, 9) that taper slightly into blunt, slightly curved or straight echini of ca. 1.5 to 2 µm length (Plate VI, 9).

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Occurrence: I-14-1

Remarks: LM and SEM images of this pollen resembles the description and LM images of Iodes

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taxa in Lobreau-Callen (1972, plate 16 figs. 34-37) and SEM images of Polyporandra scandens Beccari in Lobreau-Callen (1973, page 62, plate 7, fig. 13, 14). Polyporandra scandens is a basionym of the new comb. Iodes scandens (Beccari) Utteridge et Byng in Byng et al. (2014). Habitat today: Iodes/Polyporandra scandens is a SE Asian liana (Malesia, Papua New Guinea Mabberley, 1997) occurring in the Af climate zone.

Unknown, extinct Operculumpollis operculatus Sun, Kong et Li (Plate VI, 10-12) Description LM: Tricolpate and operculate pollen grain, can be fossilized in two ways: Either oblate with compressed shortened polar axis then having trilobate to circular outline with protruding

ACCEPTED MANUSCRIPT operculi in polar view or prolate, compressed perpendicular to the polar axis then having an elliptic outline in equatorial view (Plate VI, 10); equatorial diameters of oblate pollen range from 17.9 to 20.5 µm (N=2) and from prolate pollen ca. 12 µm whilst polar axis is ca. 18.4 µm and colpi are ca. 13.2 µm (N=1); wall thickness ca. 1.1 to 1.3 µm with the sexine thicker than nexine, reticulate. SEM: The ectexine is semitectate, micro-reticulate to reticulate, heterobrochate (Plate VI, 11, 12)

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with poly-angular to slit-like brochi of ca. 0.5 to 1.5 µm in diameter, muri are simplicolumellate, 0.7 to 1 µm wide and covered regularly with micro-verrucae and micro-rugulae perpendicular to the

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muri (Plate VI, 11, 12); colpus membranes are densely covered by micro-rugulae and micro-

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verrucae (ca. 0.25µm diameter; Plate VI, 12). Occurrence: I-14-1, I-14-3, III-2-2.

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Remarks: Botanical affinity unknown, this pollen taxon has been found also by Lei et al. (1992,

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plate 6, figs. 51, 52) in the Changchang Formation and has a wide stratigraphical range from the

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middle Eocene (Asia) to Miocene (Europe).

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4. Discussion

This SEM investigation of pollen from the Changchang Formation has not only revealed

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several previously unknown plant taxa but also some that have been previously misidentified because they were based only on LM investigations (Cornus-, Craigia-, cf. Dipterocarpus-, cf. Dryobalanops-, Flueggea-, Lagerstroemia-, Laurelia-, Mappia/Nothapodytes-, Mortoniodendron-, Phyllanthus Eriococcus/Isocladus-types) and a few that were identified correctly with LM investigations (Fagus-, Iodes-, Juglans-, Nyssa-, and Symplocos-types) by earlier workers.

Laurelia-type. Atherospermataceae fossils are rare and, of those pollen identified as Atherospermataceae, the affiliation has often been doubtful (see excellent summaries on Atherospermataceae fossil wood, leaves and pollen in Conran at al., 2013; Knight and Wilf, 2013). In the southern hemisphere, the fossil record of Atherospermataceae commences with a fossil pollen

ACCEPTED MANUSCRIPT grain (LM investigation only, documentation lost) and fossil wood from Antarctica, both of Late Cretaceous age (Mohr pers. com. in Renner et al., 2000; Poole and Francis, 1999). This is followed by lower Eocene Atherospermataceae leaves affiliated to Daphnandra and Doryphora (Knight and Wilf, 2013) from Patagonia, followed by lower Miocene Laurelia leaves from New Zealand (Lee et al., 2012; Conran et al., 2013). In the northern hemisphere, occurrences of Atherospermataceae- like

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wood was recorded from the upper Eocene of Germany (Gottwald, 1992), the Oliogocene of Egypt (Kräusel, 1939) and pollen affiliated to Laurelia from the lower Eocene of Austria (Hofmann et al.,

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2015a). Despite the fact that our Laurelia-type pollen is, unfortunately, not completely preserved,

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we are confident of the affiliation (see discussion on fossil preservation in Hofmann et al., 2015a). As a member of the more derived Laurelia-Laureliopsis clade sensu Renner et al. (2000), its

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presence from the early Eocene in Europe to the middle to late Eocene on Hainan might indicate a

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wide distribution in the boreotropics from the western Tethys towards South China. This distribution could have been facilitated by the wind dispersal of the seeds (see Renner et al., 2000,

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fig. 1). The global cooling at the end of the Eocene pushed the members of the clade back to warmer regions in the northern and the southern hemisphere, resulting in their presence in

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Oligocene sedimentary rocks of Egypt and Lower Miocene sediments in New Zealand.

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Arecaceae. Palms are assumed to be of Laurasian origin and the Coryphoideae subfamily was the latest to be dispersed into their present-day habitats (Baker and Couvreur, 2013a, b; Couvreur et al., 2011). The occurrence of lower and mid-Eocene Coryphoideae pollen types in Europe that share characters from different subtribes (Hofmann 2015a; Hofmann and Gregor, 2018) demonstrates that coryphoid pollen grains are not helpful for subtribal classification. Remarkably, our pollen taxon from Hainan resembles some species of the tropical species-rich Licuala, some species of temperate to warm Trachycarpus, and temperate to subtropical and tropical Livistona. If our fossil Trachycarpeae pollen were taken to point to Livistona, it would corroborate the finding of a leaf fragment of a fossil Livistona on Hainan by Zhou et al. (2013). Additionally, ancient relatives (e.g., fossil “Trachycarpus”) were present from the lower to mid-Eocene in Europe (Dransfield et

ACCEPTED MANUSCRIPT al., 2008; Hofmann et al., 2015a), thus supporting the stem age of ca. 48.57 Ma and the Eurasian origin for the Trachycarpeae, as suggested by Baker and Couvreur (2013a, table 1; 2015b, fig. 2).

Phyllanthaceae. The earliest occurrence of Phyllanthaceae might be Phyllanthocarpon singpurensis Kapgate, Manchester et Stuppy, a fossil diaspore from the late Cretaceous

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Intertrappean beds in India (Kapgate et al., 2017). Since then, fossil phyllanthaceous diaspores have been encountered from the early to middle Eocene in England and Germany, respectively (Reid and

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Chandler, 1933; Chandler, 1962; Collinson et al., 2012) and North America (Dilcher and

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Manchester, 1988). The English findings have been affiliated with Flueggea virosa and F. suffruticosa and assumed to represent a connecting link between the two species by Webster (1984).

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Phyllanthaceae pollen have rarely been found and these are often doubtful because of the use of LM

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only. SEM investigations revealed lower Eocene Flueggea pollen taxa from English and Austrian sedimentary rocks and mid-Eocene coals from Germany (Hofmann et al., 2015b; Hofmann and

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Gregor, 2018), with which the Flueggea-type pollen from Hainan is very comparable, suggesting a Eurasian origin of Flueggea. It is notable that on Hainan today F. suffruticosa is still growing.

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These plants produce indehiscent drupaceous fruits that are today bird- or mammal dispersed (Esser, 2003; Hoffman et al., 2006) and it can be assumed that this dispersal could have facilitated

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the migration of plants into new habitats also during the Eocene. Extant shrub taxa of Phyllanthus of the subgenera Eriococcus and Isocladus are also present on Hainan today: Their probable precursor from the middle to late Eocene Changchang Formation are described as Phyllanthus subgenus Eriococcus/Isocladus-types (= Retimultiporopollenites in Lei et al. 1992). These pollen types are only known from China. The presence of phyllanthaceous pollen might be corroborated by the occurrence of Paraphyllanthoxylon hainanensis Feng et Jin from the Changchang Formation, a fossil wood with affinities to Phyllanthaceae or Elaeocarpaceae (Feng et al., 2010).

Fagus-type. The Fagaceae are a small family with few genera but nevertheless its members

ACCEPTED MANUSCRIPT represent the most common trees in northern hemispheric forests, such as in mixed mesophytic temperate forests and Laurisilva (Denk, 2003; Grimsson et al., 2016). A high portion (ca. up to 80% of the pollen sum) of pollen from the Changchang Formation analysed with LM by Yao et al. (2009) comprised various Fagaceae taxa affiliated with oak-like forms. The Fagus-type documented here is very reminiscent to the oldest Fagus pollen in the fossil record, the Paleocene “Fagus PT 1”

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of Grimsson et al. (2015) from the Agatdalen Formation of western Greenland, and the slightly younger lower Eocene Fagus langevinii of Manchester and Dillhoff (2004) from British Columbia

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in northwestern Canada. Both fossil pollen taxa closely resemble pollen of the extant species of

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Fagus “subgenus Engleriana” sensu Shen (1992; also see Renner et al., 2016). The data set on fossil Fagus pollen and leaves displays progressive younging in time clockwise on the northern part of the

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northern hemisphere: From western Greenland (Paleocene) westwards to western Canada (early

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Eocene) and then even further to the west to Sakhalin and Kamschatka with leaves of Fagus napanensis Fotjanova (cited in Denk and Grimm, 2009 fig. 10A) of late Eocene age. The latter

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Fagus occurrence in northeast Asia is now corroborated by our middle to late Eocene Fagus-type pollen on Hainan, and suggests that the genus Fagus must have arrived earlier in Asia to spread into

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southern areas. We suggest that our Fagus-type pollen might belong to or is close to an ancient lineage of Fagus “subgenus Engleriana” (Denk 2003; Grimsson et al., 2016; Renner et al., 2016)

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that was present in eastern Asia around the middle to late Eocene times. Fagaceae diaspores today, and probably in the past, are animal dispersed. Their ability to float in water and dispersion by migrating animals might have helped to spread this taxon so widely.

Juglans-type. The oldest fossil of Juglans are middle Eocene fruits of Juglans clarnensis Scott section Rhysocaryon from Oregon (U.S.A.), whereas fossil fruits of Juglans section Trachycaryon (American butternuts) appear from the early Oligocene onwards: For example, Juglans lacunosa Manchester (Manchester 1987) from northwestern Washington (USA) and the middle Oligocene Juglans bergomensis (Balsamo-Crivelli) A. Massal (= J. tephrodes Unger in Manchester, 1987, is a younger synonym after revisions of Martinetto et al., 2015; van der Ham,

ACCEPTED MANUSCRIPT 2015), that was widespread during the Neogene of western Europe (Kirchheimer, 1957). The latter generally looks like the extant American J. cinerea (see Manchester, 1987, 1989), but systematic comparisons of the numerous European nuts of J. bergomensis and extant American J. cinerea are lacking (see Martinetto et al., 2015, van der Ham, 2015). On the other hand, the Asian butternuts (Juglans section Cardiocaryon) are reported to appear much later, during the Miocene. For

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example, J. megacinerea Miki ex. Chaney in Japan, which has been affiliated with the extant Asian taxa J. cathayensis and J. manshurica by Manchester (1987). Our Juglans-type pollen from Hainan

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can probably be affiliated with Juglans section Cardiocaryon and is contemporaneous with the

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fossil Juglans clarnensis (section Rhysocaryon) from the U.S.A.; this demonstrates that the sections Rhysocaryon and Cardiocaryon must have already been separated before the middle Eocene and

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dispersed into North America and China. This fossil evidence contradicts the molecular data and

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BEAST chronogram by Zhang et al. (2013, fig. 5), where the two above mentioned sections were inferred to split during the late Miocene, but supports both the divergence times reconstructed from

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complete chloroplast genome sequences of Juglans by Dong et al. (2017) and to some extant the results of molecular phylogenetic studies of Juglans by Aradhya et al. (2007), who proposed that

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the butternuts evolved and radiated independently from the northern latitudes and probably do not share a common ancestor with section Rhysocaryon. However, even Aradhya et al. (2007) lament

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the lack of fossil evidence in Eurasia for supporting a good phylogenetic and biogeographic analysis. Aradhya et al. (2007) suggested that the Asian sections Cardiocaryon and Juglans are closely related and may have evolved from a distant common ancestor in Eurasia and not America, a hypothesis that has been also suggested by Martinetto et al. (2015) based on fossil occurrences. We suggest that our Juglans-type pollen from Hainan might be close to an ancestor lineage of Cardiocaryon or even a member of the lineage Cardiocaryon. Fruit dispersal of butternuts today is mostly done by mammals (e.g., dyszoochory of rodents) and it can be assumed that the same dispersal mechanism played a major role during the Cainozoic times.

Lagerstroemia-type. Lythraceae leaf fossils are known since the late Paleocene and lower

ACCEPTED MANUSCRIPT Eocene from the Indian subcontinent (Lakhanpal and Guleria, 1981; Lakhanpal et al., 1984). For example, Lagerstroemia patelii Lakhanpal et Guleria was affiliated with extant L. speciosa (Linné) Persoon. The presence of Lagerstroemia leaves on the Indian subcontinent up to Miocene times is taken as evidence for wet, subtropical climate conditions (see Graham, 2013, for more data). Presumable Lagerstroemia pollen have been found in SE Asia from the middle Eocene onwards

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(e.g. on Java) and have been interpreted to represent “ancestral Lagerstroemia” by Morley (2000). Unequivocal Lagerstroemia pollen have been investigated by LM and SEM from the Miocene

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Xianan Shan Formation of eastern China (L. cathayensis in Liu et al., 2008, resembling L. limii and

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L. subcostata). Our pollen taxon closely resembles both the two extant taxa mentioned above and the fossil one and is interpreted to be an old representative of this Lagerstroemia lineage, whose

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precursors probably came from India.

Malvaceae. The presence of Craigia-type pollen corroborates the finding of Craigia

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hainanensis Jin, Kodrul, Liao et Wang (Jin et al., 2009) from the Changchang Formation. Craigia was a widespread taxon on the northern hemisphere during early Eocene to Pliocene times (Kvacek

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et al., 2005).

The two other Malvaceae pollen types from the Changchang Formation are affiliated with

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Mortoniodendron. After Nyffeler et al. (2005), Mortoniodendron is now incorporated into the clade Tilioideae in such a way that the Neotropical Mortoniodendron is sister to northern hemispheric Tilia Linné and the Chinese Craigia. Other fossil occurrences of Mortoniodendron pollen (cooccurrences with Craigia) are from the middle Eocene Messel locality in Germany, where Mortoniodendron pollen were found adhered to a leg of a Electrapis sp. bee (Grimsson et al. 2017), and from the Paleocene-Eocene-boundary section at Brixton in England (unpublished material of Hofmann). The other fossil occurrences are from middle and upper Miocene deposits of Central America (Mexico and Panama), which is also the area of the modern day distribution of Mortoniodendron. It is possible that this genus was present in South America during the Paleogene, hidden, for example, under the various Retibrevitricolpites Van Hoeken-Klinkenberg or

ACCEPTED MANUSCRIPT Bombacacidites (Couper) Krutzsch taxa occurring from the late Paleocene to early Eocene of Columbia (e.g., Jaramillo and Dilcher, 2001, plate 15 figs. 28-31). The fossil data suggest a widespread distribution of Mortoniodendron in the tropical and boreotropical realms in Laurasia (and probably the Americas). The wide distribution during Eocene times was probably helped by their wind dispersed fruits. After the late Eocene-Oligocene global cooling event, the genus found

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refuge in Central America where it is still present.

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Dipterocarpaceae. Dipterocarpaceae are thought to have had their origins in Gondwana and

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moved with the Indian plate towards Asia (Ashton and Gunatilleke 1987, Ashton, 2003). The oldest (early Eocene) dipterocarp fossils from India are probably pollen (Dutta et al., 2011, Rao et al.,

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2013, but see results section) and wood resin (Rust et al., 2010). The occurrence of dipterocarp

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fossils are taken as evidence for the existence of ancient tropical rain forests in western India persisting during the northward migration of the subcontinent from the Paleogene onwards (Shukla

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et al., 2013). However, Shukla et al. (2013) argue that the onset and growing intensity of the south Asian monsoonal circulation, approximately around the middle Miocene, led to drier conditions and

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the disappearance of the dipterocarps from many parts of India. In SE Asia, dipterocarp pollen are known since the Oligocene (e.g., Borneo, Muller, 1981), and, in contrast to Shukla et al. (2013), the

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onset of Dipterocarpaceae radiation in SE Asia is explained by the development of a pronounced, drier, monsoonal circulation instead of perhumid conditions during the Oligocene to early Miocene times (Morley, 2000). Leaf and fruit fossils assigned to various extant genera, such as Dipterocarpus, Shorea Roxburgh and Hopea Roxburgh, occur in the late Eocene of South China (Feng et al., 2013), later in the Miocene of India (Khan and Bera, 2010; Shukla et al., 2012, 2013; Khan et al., 2016) and southeast China (Shi and Li, 2010; Shi et al., 2014). Also, Miocene fossil wood was affiliated with the extant Dryobalanops (Kuramasamy and Elayaraja, 2016). However, despite of the lack of pre-Oligocene macro- and microfossils in SE Asia, the geochemical biomarker bicadinane, originating from Dipterocarpaceae resin (van Aarssen et al., 1992), is regularly encountered in petroleum source rocks of Myanmar and indicates that dipterocarps were

ACCEPTED MANUSCRIPT present during the middle to late Eocene at the same latitude as Hainan, but further to the west. This biomarker perfectly supports the occurrence of our two pollen taxa affiliable to cf. Dipterocarpus and cf. Dryobalanops and the dipterocarp findings of Feng et al. (2013) in South China.

Cornus-type. The genus Cornus generally comprises woody shrubs and small trees that are

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more or less distributed all over the northern hemisphere, growing under temperate to subtropical climates. However, there are a few outliers: Three herbaceous circum-boreal taxa and two tropical

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taxa, in South America and eastern Africa (Eyde, 1988; Xiang et al., 2006). Cornus, which has ca.

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58 species, has been divided into four major clades by molecular and morphological analyses (Xiang et al., 2006): The blue-or-white- fruited clade, the cornelian cherry clade, the big-bracted

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clade and the dwarf dogwood clade. Xiang et al. (2005) also suggested that the origin of the

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cornelian cherry clade might be rooted in Europe. However, that suggestion has been challenged because more diaspore fossils of ancient lineages of Cornales have been recovered recently from

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Upper Cretaceous to Paleogene strata of northern U.S.A and Japan (Atkinson, 2016, Stockey et al., 2016; Takahashi et al, 2002). Furthermore, fossil fruits of true cornelian cherries were found at the

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Cretaceous-Palaeogene boundary in India (Manchester and Kapgate, 2014) and in Campanian strata on Vancouver Island (Atkinson et al., 2016). Additionally, there are numerous fruit and leaf fossils

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of Cornus known from North America, Siberia, Europe and China that occurred since the late Paleocene (summarized in Eyde, 1988, Manchester et al., 2009, 2010, Kirchheimer, 1957, Mai and Walther, 1978, 1983). Cornus-type pollen (cf. subgenus Kraniopsis, blue-or-white fruited clade) has been found in Campanian/Maastrichtian strata in Siberia (Hofmann et al., 2014, and unpublished data), and Cornus of an unknown subgenus from the middle to upper Eocene strata in the Maoming basin (South China, Aleksandrova et al., 2015). Our Cornus-type pollen from Hainan resembles pollen of temperate Cornus species of the blue-or-white fruited clade and significantly postdates a fossil Cornus fruit from Santonian/Campanian sediments in Sweden (Friis pers. com in Eyde 1988), that is assumed to belong to subgenus Mesomora (= “blue fruit line“ of Eyde, 1988 = blue-or-white fruited clade of Xiang et al., 2006). This shows that the blue-or-white fruited clade was, additionally

ACCEPTED MANUSCRIPT to Europe, also present at least on Hainan, and most likely in other places in Eurasia, during the middle to late Eocene and possibly from the Late Cretaceous onwards. The fossil data corroborates a wide Eurasian and North American distribution of different Cornus clades during the Late Cretaceous and Paleocene, and presumably a much earlier diversification age into subgenera than previously estimated. This wide Eurasian distribution of Cornus might be explained by the fact that,

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in the geological past, fruits were as attractive to birds as they are today (see discussion in Eyde,

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1988). In particular, migratory birds could have kept such a widely stretched populations alive.

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Nyssa-type. Today, the genus Nyssa has a disjunct distribution in the southern United States and Costa Rica (four species) and east Asia (three species; Wang et al., 2012). However, the fossil

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record shows that, since the late Palaeogene, Nyssa fruits and pollen were present in North America

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(e.g., Dilcher and McQuade, 1967; Manchester, 1994), Europe (e.g., Chandler, 1926; Grimsson et al., 2017; Mai and Walther, 1978; Reid and Chandler, 1933) and Kazakhstan (Kuprianova, 1960),

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and from the Oligocene onwards also in Asia (Eyde, 1997; Dorofeev, 1963). Nyssa has not been reported from tropical realms (Morley, 2000) and that might be explained by the fact that they do

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not germinate at temperatures higher than 31°C (summarized in Eyde, 1997). Our Nyssa-type pollen looks like the pollen of the extant Asian N. sinensis and Nyssa pollen from the middle Eocene of

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Germany (Göschl, 2008; Grimsson et al., 2017) but not like the middle Eocene taxon from Canada depicted in Göschl (2008). The existence of an ancient population comprising a lineage leading to Nyssa sinensis can probably be supported by the presence of Palaeogene Nyssa pollen in Kazakhstan and northernmost Siberia (Kuprianova, 1960) and by Oligocene-Miocene aged fruits of Nyssa siberia Dorofeev ex. Zhilin (western Siberia) that are close to the N. sinensis (like N. sinensis, they have stones with sunken bundles that are small, see Eyde, 1997). This Eurasian population was probably kept alive through bird dispersal of these small stoned Nyssa taxa and water transport (Du et al., 2009; and see Eyde, 1997, page 111, 112), despite the open Turgai Strait (Tiffney and Manchester, 2001) within that time interval.

ACCEPTED MANUSCRIPT Symplocos-types. The Symplocaceae family contains, next to Cordyloblaste Hensch ex. Moritzi, the large genus Symplocos (300 to 340 taxa according to Fritsch et al., 2008; Manchester and Fritsch, 2014), which mostly comprises evergreen trees and shrubs that grow under humid conditions in mountain areas in the subtropical to tropical realm of the Americas, eastern Asia and Australasia (Fritsch et al., 2008). There are only two temperate deciduous species: Symplocos

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tinctoria (subgenus Symplocos) from the SE of the United States and Symplocos paniculata of subgenus Palura in eastern Asia. Molecular phylogenetic analysis of Symplocaceae has shown that

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Symplocos paniculata, together with Cordyloblaste, belong to early diverging lineages within the

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Symplocaceae (Wang et al., 2004; Fritsch et al., 2008). Symplocos has a very good fossil record in Europe, ranging from the Paleogene onwards: Fruits have been treated by Kirchheimer (1957) and

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Mai and Martinetto (2006) and pollen by Gruber (1996). Our three pollen taxa from Hainan can be

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securely affiliated with the Symplocos subgenus Palura, which today is represented by the deciduous understorey tree Symplocos paniculata, because of its reticulate-rugulate exine, which is

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unique in this genus (Wang et al., 2004, page 1910, they used the term suprareticulate). Of the fossil Symplocos pollen depicted in Gruber (1996), only three of the oldest late Eocene pollen taxa

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(Symplocos sp.1, sp. 3. and sp. 5) from Haselbach in Germany show obvious similarities to our Hainan Symplocos subgenus Palura-types. Therefore, we suggest that these six Eocene pollen taxa

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from Hainan and Europe might represent ancient members of the early diverging subgenus Palura that were probably inhabiting a boreotropical realm extending from Europe to at least South China. This data might be supported by the presence of Eocene Symplocos pollen in Kazakhstan (Kuprianova 1960). The migration of this group from west to east or vice-versa was probably facilitated by bird fruit dispersal: The extant S. paniculata has blue berries rich in fatty acids (Liu et al., 2012) that are very attractive to birds, herbivores and omnivores (see Sathyakumar and Viwanath, 2003, who demonstrated that bear digestion helps the germination of Symplocos theifolia seeds). In particular, the dispersal by migratory birds could have aided its migration across the Turgai Strait, which closed at the end of the Eocene (see Manchester and Fritsch, 2004, Tiffney and Manchester, 2001).

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Icacinaceae. The family of Icacinaceae Miers is pantropical and comprises trees, shrubs and lianas. Fossil seeds of some of the liana taxa belong to the Icacina-group (Kårehed, 2001), which are well documented in the fossil record of Europe and the United States from the early Eocene onwards (Reid and Chandler,1933; Chandler, 1961; 1962; Stull et al., 2016; and Allen et al., 2015;

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Pigg et al.; 2008; Stull et al., 2011, respectively). The revision of Stull et al. (2016) revealed that the genus Iodes Blume is represented in Europe by five diaspore taxa in the London Clay Formation.

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Despite this knowledge, the presence of Iodes-type pollen in the fossil record is somewhat

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camouflaged by the fossil pollen taxon Compositoipollenites rhizophorus Potonié, which has been assigned to Iodes by Krutzsch (1970a, 1970b) on the basis of light microscopy only. Unequivocal

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Iodes-type pollen do occur in the lower and middle Eocene of Europe (Hofmann et al, 2012,

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Hofmann and Gregor, 2018). Therefore, the additional presence of different Iodes-type pollen in the Changchang Formation underlines a boreotropical distribution of this taxon in the northern

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hemisphere during the Eocene (unfortunately, so far, no fossil data exists from the southern hemisphere). It is remarkable that Iodes-type sp. 1 resembles modern taxa from Africa and

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Madagascar and Iodes-type sp. 2 resembles a Papua New-Guinea taxon. Therefore, the present-day Old World disjunction of Iodes in Africa/Madagascar on one side, and in Papua New-Guinea on the

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other, is a relict of the Eocene period, where many species of this genus were apparently much more widely distributed than today and became extinct during the Late Eocene-Oligocene global cooling. A more remarkable disjunction is demonstrated by the third Icacinaceae taxon, resembling the extant Central American genus Mappia and the SE Asian genus Nothapodytes; neither taxa has been found in the fossil record yet. Morphological and molecular data on Icacinaceae revealed that Mappia is sister to Nothapodytes (Angulo et al., 2013, Kårehed, 2001) and both together form a clade that has been shown to be sister to the whole Icacina-group of Kårehed (2001; Byng et al., 2014). The presence of such a taxon on Hainan during the middle to late Eocene demonstrates that former (or close) members of Mappia-Nothapodytes clade must have been much more widespread during the Palaeogene and that the late Eocene-Oligocene global cooling resulted in a migration to

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Operculumpollis operculatus. Despite the application of the SEM, we still do not know where this pollen taxon belongs. However, it cannot be assigned to the Hamamelidacese Disanthus

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Maximovich, because the ectexine looks completely different.

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4.1. Remarks on palaeoclimate interpretations inferred from present-day relatives.

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The climatic requirements after Köppen-Geiger (classification updated by Kottek et al., 2006; Rubel et al., 2017) of the present day relatives of the 21 fossil accessorial pollen taxa

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investigated from Hainan are summarized in Table 1. Of these present-day relatives, five taxa

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(Phyllanthus subgen. Eriococcus/Isocladus-type sp.1, cf. Dryobalanops-type, cf. Dipterocarpustype, and the two Iodes-types) are mostly evergreen and occur in A climate zones (“equatorial”

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climates with a temperature range > +18°C, either constantly humid, or with precipitation during monsoon, winter or summer). Four taxa (Laurelia-type, Eriococcus/Isocladus-type sp. 2, Fagus

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“subgen. Engleriana”-type, and Nyssa-type) are mostly deciduous and occur in C climate zones, (“warm temperate” climates with a temperature range between -3°C > Tmin > +18°C). Four taxa

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can occur in both C and A climate zones and are mostly evergreen. Six taxa occur in both C and D climate zones, in which the D climates are “snow climates” with temperatures going down to < 3°C. Considering the precipitation, only the Laurelia-type and Iodes-type sp. 2 require fully humid conditions (in both A and C climate zones). 18 taxa are adapted to a range between mostly winter dry, monsoon precipitation, and fully humid conditions (A, C and D climate zones). One taxon prefers winter dry conditions only (Phyllanthus subgen. Eriococcus/Isocladus sp. 2). This mixture suggests a situation more in a warm temperate than a tropical realm, probably under conditions where the precipitation was less pronounced during the winter time and could reach fully humid conditions. Somewhat comparable generalised observations were made by Lei et al. (1992) and Yao et al. (2009), whilst Spicer et al. (2014) also suggested slightly drier winter months. However,

ACCEPTED MANUSCRIPT because, so far, only a small part (21 taxa) of the palynological data from the Changchang sediments have been assigned to the Köppen-Geiger climate classifications, these results should be regarded as a preliminary estimation.

5. Conclusions

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Samples of middle to late Eocene age from the coal-bearing Changchang Basin (Hainan island, China) have been palynologically analysed by the routine application of the LM and SEM.

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The samples are generally characterized by up to 80% of Fagaceae pollen (various oak-like types)

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and diverse assemblages of other angiosperms that occur in low numbers. Gymnosperms and ferns are either rare or not very abundant. Here, we present new pollen taxa and botanical affiliations and

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their implications on the palaeogeographical distribution of certain angiosperm taxa during the

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Paleogene.

The presence of Atherospermaceae (cf. Laurelia-type) pollen on Hainan is further evidence

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of the wide geographical range of this family, which was also present in Patagonia and Europe during the early Eocene, but migrated towards the subtropical zone during the early Oligocene

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global cooling event.

Flueggea-type, of the Phyllanthaceae, was present in Europe (lower Eocene) and also

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Hainan, pointing towards a Eurasian origin of this genus. In contrast, fossil pollen of Phyllanthus subgen. Eriococcus/Isocladus-types are here described for the first time and, so far, occur only in China.

The Fagus-type from Hainan resembles both the extant F. subgenus engleriana and the lower Eocene Fagus pollen described from northwestern Canada. This, together with the Fagus leaf fossils described from Kamchatka, suggest an amphipacific distribution of an ancient lineage of F. subgenus engleriana during the Eocene. The Juglans-type resembles Juglans taxa from the section Cardiocaryon (Asian butternuts), which was contemporaneous with diaspores of J. section Rhysocaryon from the United States, and pushes the divergence time within this genus further back in time.

ACCEPTED MANUSCRIPT The Lagerstroemia-type pollen found, which is currently the oldest occurrence of pollen of this genus, closely resembles the Miocene Lagerstroemia cathayensis pollen from China and the extant deciduous L. subcostata and L. limii, both also from China and Korea. Of the three Malvaceae pollen found, the two pollen of Mortoniodendron-types demonstrate a remarkable palaeobiogeographical history. Today, Mortoniodendron is restricted to Central

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America and Miocene pollen of this genus have also been encountered in Central America. However, lower and mid-Eocene pollen from Europe (Brixton in England and Messel in Germany)

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and now from Hainan, indicate a far wider distribution of this genus prior to the early Oligocene

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global cooling event. The Craigia-type supports the presence of Craigia diaspores in the Changchang sediments.

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Two dipterocarp pollen types (cf. Dipterocarpus and cf. Dryobalanops) are here described

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for the first time from Chinese Eocene strata and are supported by the presence of dipterocarp biomarkers in nearby oil source rocks and macrofossils from the Chinese mainland.

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The Cornus-type found on Hainan belongs to the “blue-or-white-fruited clade” and, together with fossil data from Europe, suggests a Eurasian origin of this clade, contemporaneous with the

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presence of the “cornelian cherry clade” in the United States. Thus the divergence-time within Cornus must have been earlier than previously estimated.

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The Nyssa-type closely resembles the extant N. sinensis and Eocene Nyssa pollen from Europe, but, up to now, not the modern examples from the Americas, thus implying that there was an ancient Eurasian Nyssa sinensis lineage stretching from Europe to eastern Asia. The three Symplocos pollen are all very closely related to the deciduous Symplocos subgenus Palura, an early diverging clade within the Symplocaceae. upper Eocene Symplocos pollen from Germany (Haselbach) most likely also belong to this clade and suggest a Eurasian origin for these Symplocos taxa as well. Three Icacinaceae of the Icacina-group have been distinguished: Two Iodes types, one resembling African/Madagascar taxa and one resembling a Melanesian taxon; these new data suggest that the Old World disjunction of Iodes in Africa/Madagascar and SE Asia is a Paleogene

ACCEPTED MANUSCRIPT relict, with the members of this genus previously much more widely distributed. The third Icacinaceae taxon resembles two genera: Mappia (today Central America) and Nothapodytes (today SE Asia), both members of the Mappia/Nothapodytes clade that also must have been widespread in the boreotropical realm during the Eocene. The palaeo-climatic signals gained from this restricted data set of accessorial pollen taxa

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suggested a warm-temperate realm, presumably adjacent to the tropics, with humid conditions but

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reduced precipitation during the winter months.

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Acknowledgements

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The research was supported by the National Natural Science Foundation of China (Nos. 31770241, 41210001, 41641014, 41661134049), the State programs of the Geological Institute,

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Russian Academy of Sciences (No. 0135-2016-0001; for TK), the Russian Natural Environment Research Council (No. NE/P013805/1), the Key Laboratory of Economic Stratigraphy and

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Palaeogeography, Chinese Academy of Sciences (Nanjing Institute of Geology and Palaeontology) (No. 2016KF02), the Natural Science Foundation of the Department of Science and Technology of

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Guangdong Province (No. 2017A030310411), and the Fundamental Research Funds for the Central Universities (No. 17lgpy105). The comments of the two reviewers J.M. Bouchal and T. Denk are

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greatly acknowledged, A.H.N. Rice is thanked for correcting the English of the manuscript and the editor M. Stephenson for his careful editing.

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Figure, plate and table captions

Fig. 1.

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Sketch map of Hainan in south China and the locality of the Changchang Formation.

Fig. 2.

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Occurrences of the treated taxa during the Eocene; additionally occurrences for Cornus during the Upper Cretaceous time, for Fagus and Trachycarpeae during the Paleocene time, for Juglans during

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the Oligocene time, for Laurelia and Mortoniodendron during the Miocene time and modern

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occurrences of Laurelia, Iodes, Mappia/Nothapodytes and Mortoniodendron.

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Plate I.

Pollen types of Atherospermataceae, Arecaceae and Phyllanthaceae, magnification in the LM images x 1000, bar in the SEM overview = 10 µm, bar in the SEM detail = 2 µm.

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1.-3. Laurelia-type. 1. LM image, 2. SEM overview of the same grain as in 1., 3. SEM detail of the same grain as in 1.

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4.-6. Trachycarpeae-type. 4. LM image, 5. SEM overview of the same grain as in 4., 6. SEM detail of the same grain as in 4.

7.-9. Flueggea-type. 7. LM image, 8. SEM overview of the same grain as in 7., 9. SEM detail of the

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same grain as in 7.

10-12. Phyllanthus type sp.1. 10. LM image, 11. SEM overview of the same grain as in 10., 12. SEM detail of the same grain as in 10.

Plate II.

Pollen types of Phyllanthaceae, Fagaceae, Juglandaceae and Lythraceae, magnification in the LM images x 1000, bar in the SEM overview = 10 µm, bar in the SEM detail = 2 µm. 1.-3. Phyllanthus-type sp. 2. 1. LM image, 2. SEM overview of the same grain as in 1., 3. SEM detail of the same grain as in 1. 4.-6. Fagus-type. 4. LM image, 5. SEM overview of the same grain as in 4., 6. SEM detail of the same grain as in 4. 7.-9. Juglans-type. 7. LM image, 8. SEM overview of the same grain as in 7., 9. SEM detail of the same grain as in 7.

ACCEPTED MANUSCRIPT 10-12. Lagerstroemia-type. 10. LM image, 11. SEM overview of the same grain as in 10., 12. SEM detail of the same grain as in 10.

Plate III. Pollen types of Lythraceae and Malvaceae, magnification in the LM images x 1000, bar in the SEM overview = 10 µm, bar in the SEM detail = 2 µm. 1.-3. Lagerstroemia-type. 1. LM image, 2. SEM overview of the same grain as in 1., 3. SEM detail

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of the same grain as in 1. 4.-6. Craigia-type. 4. LM image, 5. SEM overview of the same grain as in 4., 6. SEM detail of the

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same grain as in 4.

7.-9. Mortonioden-type sp. 1. 7. LM image, 8. SEM overview of the same grain as in 7., 9. SEM

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detail of the same grain as in 7.

10-12. Mortoniodendron-type sp. 2. 10. LM image, 11. SEM overview of the same grain as in 10.,

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12. SEM detail of the same grain as in 10.

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Plate IV.

Pollen types of Dipterocarpaceae, Cornaceae, and Nyssaceae, magnification in the LM images x 1000, bar in the SEM overview = 10 µm, bar in the SEM detail = 2 µm.

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1.-3. cf. Dryobalanops-type sp. 2. 1. LM image, 2. SEM overview of the same grain as in 1., 3. SEM detail of the same grain as in 1.

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4.-6. cf. Dipterocarpus-type. 4. LM image, 5. SEM overview of the same grain as in 4., 6. SEM detail of the same grain as in 4.

7.-9. Cornus-type. 7. LM image, 8. SEM overview of the same grain as in 7., 9. SEM detail of the

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same grain as in 7.

10-12. Nyssa-type. 10. LM image, 11. SEM overview of the same grain as in 10., 12. SEM detail of the same grain as in 10.

Plate V.

Pollen types of Nyssaceae and Symplocaceae, magnification in the LM images x 1000, bar in the SEM overview = 10 µm, bar in the SEM detail = 2 µm. 1.-3. Nyssa-type sp. 2. 1. LM image, 2. SEM overview of the same grain as in 1., 3. SEM detail of the same grain as in 1. 4.-6. Symplocos-type sp. 1. 4. LM image, 5. SEM overview of the same grain as in 4., 6. SEM detail of the same grain as in 4. 7.-9. Symplocos-type sp. 2. 7. LM image, 8. SEM overview of the same grain as in 7., 9. SEM detail of the same grain as in 7.

ACCEPTED MANUSCRIPT 10-12. Symplocos-type sp. 3. 10. LM image, 11. SEM overview of the same grain as in 10., 12. SEM detail of the same grain as in 10.

Plate VI. Pollen types of Icacinaceae and indet. family, magnification in the LM images x 1000, bar in the SEM overview = 10 µm, bar in the SEM detail = 2 µm. 1.-3. Mappia/Nothapoditys-type sp. 2. 1. LM image, 2. SEM overview of the same grain as in 1., 3.

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SEM detail of the same grain as in 1. 4.-6. Iodes-type sp. 1. 4. LM image, 5. SEM overview of the same grain as in 4., 6. SEM detail of

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the same grain as in 4.

7.-9. Iodes-type sp. 2. 7. LM image, 8. SEM overview of the same grain as in 7., 9. SEM detail of

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the same grain as in 7.

10-12. Operculumpollis operculatus. 10. LM image, 11. SEM overview of the same grain as in 10.,

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12. SEM detail of the same grain as in 10.

ACCEPTED MANUSCRIPT Table. 1. Table of the examined fossil pollen taxa from Hainan and probable other fossil occurrences of these taxa and their specific affiliations to extant taxa. The geographical occurrences of the extant taxa and the climatic conditions of these geographical areas after the Koeppen and Geiger classification (updated by Rubel et al., 2017). Abbreviations: Chil = Chile, Ar = Argentina, AU = Australia, NZ = New Zealand, Ind = India, Chin = China, Vie = Vietnam, SE-AS = SE Asia, Tai = Taiwan, Thai = Thailand, Phi = Philippines, C-Am = Central America, Colu, Columbia, Mal = Malaysia, Bor = Borneo, Sum = Sumatra, Ru = Russia, E-Ru = east Russia, Ja = Japan, Afr =

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Africa, Mad = Madgascar, E = Eocene, P = Palaeocene, O = Oligocene, M = Miocene UC = Upper Cretaceous, Eu = Europe, Eg = Egypt, N-Am = North America, Grl = Greenland, Si = Siberia, N

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Hem = northern hemisphere, ?Kaz = Khazachstan, dec = deciduous, ever = evergreen.

specific

occurrences

Köppen-Geiger

other

dec/

section

affiliation with L. novae-zelandiae L. philippiana

today Chil Ar NZ

classification Cfb Cfc

fossil occurrences E: Eu Eg

evergr ever

Trachcarpeae

Trachycarpeae

Trachycarpus Licuala Livistona

Afr Ind Chin Thai Vie Af Am Aw Cfa Cfb Cwa Cwb BWh SE-As NW-Au Bsh

E: Eu

ever

S-Afr Ara Chin Ko Ja Am Aw Cfa Cfb Cwa Cwb Dwa E-Ru Dwb Dwc BSh BWh Bwk

E: Eu

dec

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F. verrucosa F. suffruticosa

Phyllanthus

P. subgen. Eriococcus /Isocladus sp 1

P. kinabaluicus P. ruber

Mal Bor S-Chin

Af Am Aw

non

ever

Phyllanthus

P. subgen. Eriococcus /Isocladus sp 2

P. chekiangensis P. leptpocladus

S-Chin

Cwa Cwb

non

dec

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Flueggea

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tribe, subgenus taxon-type Laurelia

Fagus

F. “subgen. Engleriana”

F. engleriana F. japonica

Chin

Cfa Cfb Cwa Cwb

P E: N-Am Grl,

dec

Juglans

J. section Cardiocaryon

F. mandshurica F. ailantifolia

Chin Tai Ko Ja E-Ru

Cfa Cfb Cwa Cwb Dwa Dwb

O: N-Am Eu, M: Si Ja

dec

L. limii L. subcostata

Chin Thai Vie Phi Ja

Aw Am Cfa Cfb Cwa Cwb

M: Chin

dec

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Lagerstroemia Craigia

Chin Vie

Cfa Cwa Cwb Dwc

P E: N Hem

dec

Mortoniodendron sp 1

M. guatemaltense

C-Am Colu

Af Am Aw Cwa Cwb

E: Eu M: C-Am

ever

Mortoniodendron

Mortoniodendron sp 2

M. guatemaltense

C Am Colu

Af Am Aw Cwa Cwb

E: Eur M: C-Am

ever

Dryobalanops

Mal Bor Sum

Af Am

E: Ind

ever

Dipterocarpus

SE-As

Af Am Aw

E: Ind

dec/ever

C. alba C. sanguinea C. controversa

Ru Chin Ja

Cfa Cfb Cfc Cwa Cwb Csa Csb Dfa Dfb Dwa Dwb Dwc

UC: Eu Si

dec

Dryobalanus Dipterocarpus Cornus Nyssa Symplocos

Mappia/ Nothapodythes

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Craigia

Mortoniodendron

C. subgen. Kraniopsis/Mesomora

Nyssa sinensis

Chin

Cfa Cwa Cwb

Pa E. Eu

dec

S. subgen. Palura sp 1

S. paniculata

Ind to Ja

Cfa Cfb Dwa Dwb

P E: Eu ?Kaz

dec

S. subgen. Palura sp 2

S. paniculata

Ind to Ja

Cfa Cfb Dwa Dwb

P E: Eu ?Kaz

dec

S. subgen. Palura sp 3

S. paniculata P. prunifolia

Ind to Ja

Cfa Cfb Cwa Dwa Dwb

P E: Eu ?Kaz

dec

Mappia/Nothapodythes

M. mexicana M. racemosa N. nimmoniana N. pittosporides

C-Am, Ind Thai Chin Phi SE-As

Af Am Aw As Cfa Cwa Cwb

non

ever

Iodes sp 1

I. africana I. globulifera

Afr Mad

Af Am Aw As

E: N-Am Eu

ever

Iodes sp 2

I. scandens

SE-As

Af

E: ?Eu

ever

ACCEPTED MANUSCRIPT Highlights

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Eocene pollen from Hainan were analysed with LM and SEM Eocene Eurasian populations of Cornus, Juglans, Nyssa, and Symplocos existed Dipterocarps, Phyllanthus subgen. Eriococcus/Isocladus and Lagerstroemia are Asian Laurelia, Flueggea, Iodes, and Trachycarpeae were widespread in the Eocene

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   

Figure 1

Figure 2