# Lutetian swamp-freshwater palynoflora from Bultu-Zile (central Anatolia, Türkiye): Implications for Eocene ecosystems of Balkanatolia

Benjamin Raynaud, M. Serkan Akkiraz, Anais A Boura, Carina Hoorn, Martha Gibson, Adele Giobbini, Paul Botté, Leny Montheil, Mustafa Y Kaya, Faruk Ocakoğlu, et al.

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## ► To cite this version:

Benjamin Raynaud, M. Serkan Akkiraz, Anais A Boura, Carina Hoorn, Martha Gibson, et al. "Lutetian swamp-freshwater palynoflora from Bultu-Zile (central Anatolia, Türkiye): Implications for Eocene ecosystems of Balkanatolia." Journal of Asian Earth Sciences, 2026, 300, pp.106980. 10.1016/j.jseaes.2026.106980. hal-05490528

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# Lutetian swamp-freshwater palynoflora from Bultu-Zile (central Anatolia, Türkiye): Implications for Eocene ecosystems of Balkanatolia

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Benjamin Raynaud<sup>a, *, &</sup>, M. Serkan Akkiraz<sup>b</sup>, Anaïs Boura<sup>a</sup>, Carina Hoorn<sup>c</sup>, Martha Gibson<sup>d</sup>, Adele Giobbini<sup>a</sup>, Paul Botté<sup>e</sup>, Leny Montheil<sup>e</sup>, Mustafa Kaya<sup>f</sup>, Faruk Ocakoğlu<sup>g</sup>, Deniz İbilioğlu<sup>b</sup>, Grégoire Métais<sup>a</sup>, K. Christopher Beard<sup>h</sup>, Pauline Coster<sup>i</sup>, Alexis Licht<sup>e</sup>

## ARTICLE INFO

**Keywords:**
Palynology
Paleobotany
Eocene
Embrithopods

## ABSTRACT

Balkanatolia is a south-eastern European biogeographic province that, during the Early and Middle Eocene, comprised low topography islands sustaining endemic mammalian fauna. The environmental and climatic context of the duration and, then, the end of this faunal endemism is still debated. Therefore, palynology could help us to characterize these environments and climates. Most Lutetian palynofloras from this region deposited in terminal fluvial settings (e.g. mangrove, deltaic, or shallow marine environments). Here, we present the first description of the palynoflora from Bultu-Zile, a Lutetian embrithopod-bearing locality in the Pontides (Türkiye). Unlike other Balkanatolian sites, the Bultu-Zile assemblage accumulated in a calm swamp-freshwater environment, preserving a distinctive pollen and spore record dominated by swamp and freshwater indicators such as Polypodiaceae, Lygodiaceae, Osmundaceae, Cupressaceae, and Ludwigia (Onagraceae). This depositional context also documents the earliest occurrences of Azolla (Salviniaceae) and Corsinipollenites oculusnoctis (Ludwigia, Onagraceae) in Türkiye. Lowland-riparian and montane indicators are also present in the assemblage (e.g. Fagaceae, Myricaceae, Cyrillaceae/Clethraceae, Juglandaceae, Mastixiaceae, Lythraceae, Sapotaceae, *Ilex*, *Armeria*, *Icacinaceae*, and *Vitaceae*). Quantitative climatic reconstructions using both the Coexistence Approach and CREST suggest a wet temperate climate with hot and wet summers. The Bultu-Zile palynoflora aligns with the broader Lutetian environmental and climatic framework of Balkanatolia and supports a scenario of climatic and vegetational continuity from Western Europe to Central Asia, with evergreen Fagaceae-Juglandaceae forests and mangroves along the shorelines. These findings imply that Balkanatolian faunal endemism persisted primarily due to insular isolation rather than climatic or environmental barriers.

## 1. Introduction

Eurasian Eocene mammalian faunas are traditionally divided into

two broad biogeographic areas: Western Europe and Eastern Asia (Stehlin, 1909). Recent paleontological discoveries, however, revealed the existence of a third province: Balkanatolia (Licht et al., 2022). This

<footnote><sup>a</sup> Centre de recherche en paléontologie - Paris, Centre national de la recherche scientifique, Muséum national d'Histoire naturelle, Sorbonne Université, 57 rue Cuvier, CP38, 75005 Paris, France</footnote>

<footnote><sup>b</sup> Department of Geological Engineering, Kütahya Dumlupınar University, Evliya Çelebi Yerleşkesi, Kirazpınar, Kütahya Tavşanlı Yolu 10. km, 43100 Kütahya, Turkiye</footnote>

<footnote><sup>c</sup> Department, Institute for Biodiversity and Ecosystem Dynamics, Universiteit van Amsterdam, 1098 XH Amsterdam, The Netherlands</footnote>

<footnote><sup>d</sup> PetroStrat Inc., 3760 Westchase Drive, Houston, TX 77042, United States of America</footnote>

<footnote><sup>e</sup> Aix-Marseille University, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France</footnote>

<footnote><sup>f</sup> Geological Institute, RWTH Aachen University, Wüllnerstraße 2, 52062 Aachen, Germany</footnote>

<footnote><sup>g</sup> Department of Geological Engineering, Eskişehir Osmangazi University, Büyükdere 26040 Odunpazarı/Eskişehir, Turkiye</footnote>

<footnote><sup>h</sup> Biodiversity Institute and Department of Ecology and Evolutionary Biology, University of Kansas, 1345 Jayhawk Blvd, Lawrence, KS 66045, United States of America</footnote>

<footnote><sup>i</sup> Réserve naturelle nationale géologique du Luberon, Parc naturel régional du Luberon, Géoparc mondial UNESCO, 60 Place Jean Jaurès, 84400 Apt, France</footnote>

<footnote>* Corresponding author.</footnote>

<footnote>E-mail addresses: benjamin.raynaud@mnhn.fr (B. Raynaud), mserkan.akkiraz@dpu.edu.tr (M.S. Akkiraz), anais.boura@mnhn.fr (A. Boura), m.c.hoorn@uva.nl (C. Hoorn), martha.gibson@petrostrat.com (M. Gibson), adele.giobbini@etu.sorbonne-universite.fr (A. Giobbini), botte@cerege.fr (P. Botté), leny.montheil92@gmail.com (L. Montheil), kaya@geol.rwth-aachen.de (M. Kaya), focak@ogu.edu.tr (F. Ocakoğlu), deniz.ibilioğlu@dpu.edu.tr (D. İbilioğlu), gregoire.metais@mnhn.fr (G. Métais), chris.beard@ku.edu (K.C. Beard), pauline.coster@parcduluberon.fr (P. Coster), licht@cerege.fr (A. Licht).</footnote>
former low-relief biogeographic province corresponds broadly to the current Balkans and Türkiye. From the Cretaceous until the Middle Eocene, its large islands remained isolated from Western Europe and Asia by persistent seaways, and from Africa by the Neotethys (Barrier et al., 2018). Progressive uplift of the Balkanatolian terranes, combined with sea level falls, gradually increased land connectivity between Balkanatolia and the Middle East (Licht et al., 2022). This process terminated the long biogeographic isolation of Balkanatolia during the Bartonian, a period marked by a major influx of Asia-derived taxa (Licht et al., 2022; Métais et al., 2023).

Before the establishment of a terrestrial corridor linking it with adjacent Asian terranes, Balkanatolia was characterised by an endemic mammalian fauna, which is particularly well documented by multiple Lutetian paleontological localities (Maas et al., 1998, 2001; Métais et al., 2012, 2018, 2024; Maga and Beck, 2017; Jones et al., 2019; Beard et al., 2021, 2023; Montheil et al., 2025). Iconic endemic clades include embrithopods (afrotherian placental mammals that originated in Africa; Sen and Heintz, 1979; Sen, 2013; Sanders et al., 2014; Lihoreau et al., 2023; Métais et al., 2024), anatoliadelphyids (metatherians that originated in Gondwana; Métais et al., 2018; Beard et al., 2023), and pleuraspidotheriids (archaic ungulate placental mammals that originated in Europe, where they disappeared near the Paleocene-Eocene boundary; Métais et al., 2012, 2018). The persistence of pleuraspidotheriids on Balkanatolia for ~ 13 Ma beyond their extirpation in western Europe remains enigmatic, partly because paleoecological data from Balkanatolian fossil vertebrate sites are limited. Similarly, how Gondwanan embrithopods and anatoliadelphyids succeeded in colonizing Balkanatolia without establishing a foothold in adjacent parts of Eurasia remains unexplained.

Of the endemic mammals known from Balkanatolia, embrithopods are particularly interesting because of their clear biogeographic signal and their contentious paleoecological attributes. Embrithopods have sometimes been interpreted as semiaquatic animals (Sen and Heintz, 1979; Rose, 2006; Hutchinson et al., 2011; Sen, 2013), whereas other specialists regard them as being fully terrestrial (Andrews, 1906; Clementz et al., 2008; Delmer, 2005). The common occurrence of embrithopod remains in coastal (marine, deltaic, mangrove) or swampy deposits is one of the chief arguments favouring a semiaquatic ecology for this clade (Sen, 2013; Lihoreau et al., 2023). These large-bodied herbivorous mammals are characterized by brachyodont and bilophodont molars, indicating a dietary specialization for browsing and possibly frugivory (Court, 1992). Detailed knowledge of the nature of

the environments that were occupied by the endemic mammals of Balkanatolia can be achieved through the analysis of palynological assemblages.

To date, only three Balkanatolian fossil mammal sites have yielded sporomorphs (i.e. pollen and spores, the reproductive material of plants), all of which are attributed to the Lutetian: Arabinköy (Yoncalı Formation, Çankırı Basin), the Çiçekdağı mine (Yoncalı Formation, Çankırı Basin), and the Eski-Çeltek mine (Çeltek and Armutlu Formations, Amasya area; Fig. 1; Akgün, 2002; Akgün et al., 2002; Akkiraz et al., 2008). In all three cases, palynological studies have indicated a mangrove, deltaic or shallow marine depositional environment, with evidence of transported sporomorphs related to inland ecosystems. These palynofloras present several environmental components: mangrove (e.g. *Nypa* type palm, *Avicennia* and *Pelliciera*), back-mangrove (e.g. *Araceae*, *Mauritia* and other *Arecaceae*, *Restionaceae*), swamp-freshwater (ferns, *Cupressaceae* conifer, *Nymphaceae*, *Sparganiaceae*), lowland-riparian (e.g. *Cycadaceae*, *Corylaceae*, *Icacinaceae*, *Juglandaceae*, *Myricaceae*), and montane (e.g. *Abies*, *Pinus*, *Quercus*; Akgün, 2002; Akgün et al., 2002; Akkiraz et al., 2008). These localities have been described as wet tropical (Akgün, 2002; Akgün et al., 2002; Akkiraz et al., 2008; Kayseri-Ozer, 2013), while climate parameters obtained with the Coexistence Approach on these floras correspond to a warm and wet temperate-subtropical climate (Cfa) in the Köppen-Geiger classification (Köppen, 1900; Geiger, 1954, 1961). So far, no truly continental sporomorph assemblage from the Eocene of Balkanatolia has ever been documented, and it is unclear how far the inland pollen and spores have been transported in the previously-described mangrove-dominated Eocene assemblages. The type and diversity of inland forests of Balkanatolia therefore remains indirectly known through palynomorphs, obscuring whether a distinctive Balkanatolian floral community may have promoted or enhanced the endemism of its unique mammalian fauna. In parallel, fossil wood remains from the Middle Eocene Climatic Optimum of the Tokat-Zile area indicate the presence of Lauraceae (*Actinodaphnoxylon zileensis*; warm-temperate indicator), *Arecaceae* (*Palmoxylon sabaloides*; warm-temperate to tropical indicator), *Apocynaceae* (*Apocynoxylon umuttuncii*), *Fabaceae* (*Dichrostachyoxylon zirkelii*), *Moraceae* (*Ficoxylon anatolicum*), *Cupressaceae* (*Juniperoxylon* cf. *J. acarcaea*) and *Pinaceae* (*Pinuxylon* cf. *P. tarnocziense*; Akkemik et al., 2025, 2021; Akkemik et al., 2023b, Akkemik et al., 2023a).

Here we introduce a new Eocene palynoflora from a Turkish embrithopod-bearing fossil site: Bultu-Zile. We show that its

<figure><img src="image_5.png" /><figcaption>**Fig. 1.** (A) Present-day structural map of the Balkanatolian tectonic terranes. ACP: Alcapa; An-TD: Anatolide-Tauride; D: Dacia; GA: Greater Adria; Pd: Pontides; R: Rhodope, SA: South Armenia; St: Standja Massif; T: Tisza. (B) Middle Eocene structural map of Balakanatolia displaying localities yielding endemic Balkanatolian taxa. Star: site of study with 1: Bultu-Zile; diamonds: sites with documented palynoflora with 2: Camili Mezra, 3: Çiçekdağı mine and 4: Eski-Çeltek. Squares: other Balkanatolian mammal localities with 5: Haţeg, 6: Orhaniye, 7: Boyabat, 8: Boğazlıyan. Terranes are coloured corresponding to their affinity: Eurasia (in red), Gondwana (in purple), Cimmeria (in blue). Shaded colors indicated flooded epicontinental shelf. Modified from Montheil et al. (2025).</figcaption></figure>
sporomorph assemblage is typical of a continental calm-freshwater
swamp and is the first sporomorph-bearing Balkanatolian locality
devoid of any marine influence. We also show that the Bultu-Zile
assemblage presents the first documentation of *Azolla* Lam. 1783 from
the Paleogene of Türkiye. We compare the sporomorph assemblages of
all Balkanatolian mammal-bearing localities and propose a first palae-
oecological reconstruction for its Lutetian endemic fauna.

## 2. Geological context

Balkanatolia was located between the Western European and the
Arabo-African cratons, and the Cimmerian terranes of the Middle East,
from the Paleocene to the Eocene (Licht et al., 2022). Balkanatolia is an
assemblage two sets of tectonic terranes (Fig. 1 A-B): Laurasia-derived
terranes (Tisza, Dacia, Rhodope, Standja Massif and Pontides) in the
North and Gondwana-derived terranes (Alcapa, Greater Adria,
Anatolide-Tauride and South Armenia) in the South (van Hinsbergen
et al., 2020; Mueller et al., 2022). The accretion of these terranes began
during the Albian with Dacia-Tisza accretion and ended during the late
Middle Eocene with Pontides-Taurides collision (van Hinsbergen et al.,
2020).

The Bultu-Zile locality (Fig. 2B) was initially attributed to the early Miocene (Bekmezci and Minaz, 1984), but later attributed to the Eocene when remains of the embrithopod *Palaeoamasia kansui* were documented (Kaya, 1995; Erdal et al., 2016). This locality is situated on the Pontides terrane and displays a similar stratigraphic succession as found in the nearby Çankırı Basin (Akgün et al., 2002). The embrithopod remains were collected in 20 to 60 m of lignite that belong to the Beynamaz Member of the Meryemdere Formation (Fig. 2A). This formation is composed of marine marls and sandstones with Lutetian to Priabonian nannoplankton and foraminifera (Montheil et al., 2025). Within the Meryemdere Formation, the Beynamaz Member is a 300 m thick section of andesites, tuffs, volcanic conglomerates, and interfingered lignite

beds. The lignite beds within the Beynamaz Member expose in two localities: the BZ1 mine (40°19′16.7″N, 35°41′48.4″E) which is mostly flooded and the visible lignite is reworked by recent mining activity; and the BZ2 mine (40°18′30.4″N, 35°40′40.3″E), which presents a more visible outcrop where lignite alternates with rare organic-rich mudstones, tuffs and tuffaceous sandstones. The BZ2 lignite has been dated as 46.5 ± 1.0 Ma based on U-Pb geochronological analyses of volcanic tuffs which are intercalated in the lignite beds (Montheil et al., 2025). The lignite did not yield any marine organism or any marine indicators. The presence of the embrithopod *Palaeoamasia kansui* (Kaya, 1995) seems to confirm an Eocene age as embrithopods are unknown in younger deposits of Balkanatolia (Licht et al., 2022). These constraints suggest a Lutetian age for the Bultu-Zile flora, in agreement with other age constraints for the Beynamaz Member (Montheil et al., 2025).

## 3. Material and Methods

### 3.1. Palynological sampling and extraction

Nineteen samples were collected from the lignite beds of the Bey-
nazam Member for sporomorph extraction and identification. These
samples correspond to 15 different levels within the section, plus 4
lateral duplicates (Fig. 2A). Nonetheless, the stratigraphy within the
lignite is sometimes difficult to follow, so the vertical spacing between
the samples is not completely regular (the gaps between samples varies
from 10 cm to 6.2 m) and the height difference between the lowest and
the highest samples is 15.3 m.

The palynomorph extraction has been carried out by Hasan Can
(Direnç Jeolojik Danışmanlık). The procedure included the following
steps. First, the samples were firmly grinded, followed by cold treatment
in a HCl (33%) solution for 1 to 5 h, to remove the carbonate fraction.
This step was followed by treatment in a HF (33%) solution, used to
remove the silicate fraction. HCL was added to the residue again and left

<figure><img src="image_6.png" /><figcaption>**Fig. 2.** Lithostratigraphy at the Bultu-Zile section. (A) Simplified log of Beynamaz Member, in Bultu-Zile, and palynological sampling (dots) within the lignite outcrop. (B) Simplified geological map of the Bultu-Zile area, modified from Uğuz et al., (2002). Figure modified from Montheil et al. (2025).</figcaption></figure>
to stand for approximately 2 to 3 h. Then HCL was extracted from the specimen using a centrifuge. The residue has been strained with a 10 µm mesh sieve. A ZnCl₂ dense liquor allowed to separate the organic fraction from the remnant sediment. After the ethyl alcohol washing of the ZnCl₂, the residue was diluted in distilled water and a dried at 60 to 70 °C. Finally, microscope slides were made and covered with a lamella using Elvacide.

## 3.2. Sporomorph counting

Palynological slides have been scanned in the Muséum national d'Histoire naturelle (MNHN, Paris, France) with a NanoZoomer S60 Digital slide scanner developed by Hamamatsu. Every slide was scanned with 11 clarity levels, 2 µm spaced, and the scans have been stacked. Sporomorphs are directly counted on the stacked scans, using both scans and light microscopy observations (through a Zeiss Axiolab AX10 Lab. A1 microscope) for identification. For each slide, when possible, we counted up to 200 specimens (i.e. 5 slides out of 19 did not reach the 200 benchmark; see Supplementary data 1). Bisaccate pollen grains were counted separately from the 200 sporomorphs per slide as they are produced in high amounts and can easily be dispersed across a wide area (Cour et al., 1999; Lu et al., 2008; Zhou and Li, 2012).

After counting, two multivariate analyses have been applied: a clustering analysis based on CONISS (Grimm, 1987) in Tilia v3.0.3 and non-metric multidimensional scaling (NMDS; Kruskal, 1964) using R. Our aim was to highlight possible variations in the sporomorph and environmental composition of the assemblage throughout the stratigraphical sequence. The NMDS differs from the clustering analysis in that it does not treat stratigraphic order as a constraint.

## 3.3. Climate reconstruction

The Coexistence Approach (CA) is a method commonly used in climate reconstruction for Neogene paleofloras (Mosbrugger and Utescher, 1997; Utescher et al., 2000, 2007; Akgün et al., 2007; Ivanov et al., 2012). Moreover, floral communities from the Paleogene, particularly Eocene basins, were also employed in the relevant method (Akkiraz et al., 2006, 2008, 2022; Utescher et al., 2011; Durak et al., 2025). We applied this method to the palynological data from Bultu-Zile. The CA is a non-probabilistic approach using the principle of Nearest Living Relative (NLR): after having identified the NLR of every morphotaxa, the overlap between NLR climatic parameters (e.g. mean annual temperature, warmest month temperature, mean annual precipitation) is used to define the paleoclimatic parameters of the site (Mosbrugger and Utescher, 1997). As it is a non-probabilistic method, it does not provide statistical uncertainty (Gibson et al., 2022).

In addition, Climate Reconstruction SofTware (CREST) was applied to Bultu-Zile floral data (embryophytes except Pinaceae) using the R package *crestr* (Chevalier et al., 2014; R Core Team, 2021; Chevalier, 2022). This probability density function (PDF)-based quantitative method uses GBIF global plant distribution data to infer the climatic parameters of the fossil site from its plant assemblage. We applied it here using two types of approaches. First, we treated the sporomorph counting as presence-absence data, meaning that each taxon was given equal weight in the analysis. Second, we treated the counting as relative abundance data, where the most abundant taxa were assigned greater weight. When a morphotaxon corresponded to several NLR taxa, all NLRs were included in the analyses and weighted to avoid overrepresentation. To balance computational efficiency and precision, we set the minimum number of unique presence data necessary to estimate a species' climate response to 10, and the number of points to be used to fit the PDFs to 50,000.

In aiming to reconstruct deep-time climate with CREST, a caveat must be considered. Like CA, CREST applies the principle of actualism using nearest living relatives (NLRs). The further back in time we go, the more cautiously results must be interpreted, since the ecological and

climatic preferences of plant taxa may have changed over macroevolutionary time scales (Grimm and Denk, 2012; Grimm et al., 2016; Grimm and Potts, 2016). Nevertheless, successful applications of the NLR approach in deep time do exist and justify its use – with caution – on Eocene flora, such as the studies of Uhl et al., (2003), Roth-Nebelsick et al. (2004), Mosbrugger et al. (2005), Poole et al. (2005), Pross et al. (2012), Klages et al. (2020), which demonstrated that an NLR-based method on Cretaceous or Paleogene flora are consistent with geochemical reconstructions or alternate paleobotanical proxies that are not based on the Coexistence Approach (such as CLAMP).

# 4. Results

## 4.1. Taxonomic composition

A total of 7,154 pollen and spores have been counted in the 19 studied samples (including 3,653 bisaccate pollen grains, Fig. 3 A-B, 51%). Among the 49% of non-bisaccate pollen and spores, there are 2,318 fern and lycophyte spores (66.2% of the non-bisaccate pollen and spores; Table 1), 592 non-bisaccate conifer pollen (16.91%), 13 cycad-ophytes pollen (0.37%), 3 monocotyledon angiosperm pollen (0.09%) and 575 eudicotyledon angiosperm pollen (16.42%).

Non-pollen palynomorphs (NPP) are also present in our samples. *Azolla* Lam. (Lamarck, 1783) ferns are documented for the first time in the Paleogene of Türkiye; 299 *Azolla* microspore massulae have been counted in Bultu-Zile samples (Fig. 3C). *Ovoidites* Potonié, 1951 charophyte spores (Fig. 3D) have also been found, as well as *Botryococcus Kützing*, 1849 trebouxiales algae (Fig. 3E). Fungi are also common in Bultu-Zile assemblage (Fig. 3F). We also note the great amount of organic debris (Fig. 3G).

There are 2,318 ferns and lycophytes spores, which represents 66.2% of the 3,501 non-bisaccate pollen and spores. Among them, we note the presence of Salviniaceae spores (a family which includes the genus *Azolla*): *Hydrosporis levis* (27 spores, 1.16%; Fig. 4A). *Leiotriletes* (Fig. 4B) is by far the most common fern genus, with 1,402 spores (60.5% of fern and lycophyte spores). Different kind of ferns are documented: *Lycopodium* (*Retitriletes* sp., Fig. 4C; 182), Polypodiaceae (*Polypodiaceoisporites* sp., Fig. 4D, *Verrucatosporites* sp.; 119), *Pteris* (*Polypodiaceoisporites* sp., *P. saxonicus*; 119), *Osmunda* (*Baculatisporites* sp., *B. nanus*; 41), Lygo-diaceae (*Leiotriletes maxoides maxoides*, *Trilites multivalatus*, *T. embry-onalis*; 9), Gleicheniaceae (*Gleicheniidites* sp.; 9), Dennstaedtiaceae (*Leiotriletes microlepidioides*, *Verrucatosporites favus*, Fig. 4E; 7). *Tripla-nosporites* spp. fern spores are also present (Fig. 4F; 170). Finally, some lycophytes are present through the Selaginellaceae family (*Echinatisporis* sp., Fig. 4G; 95).

Cycadophytes (13 specimens, 0.37% of non-bisaccate sporomorphs) are only represented by *Cycadopites* sp. and *C. lusaticus*, and conifers are represented by Cupressaceae (*Inaperturopollenites* spp., Fig. 4H) and *Tsuga* (*Zonalapollenites* sp.; Fig. 4I). The only counted monocotyledons are Sparganiaceae (*Sparganiaceaeapollenites polygonalis*, Fig. 4J).

Another taxon is documented in the Eocene of Türkiye for the first time, the genus *Corsinipollenites* (Onagraceae), through the species *C. oculusnoctis* (*Ludwigia*) which represents 81.4% of angiosperm pollen from Bultu-Zile (468 grains; Fig. 4 K-L). Apart from *C. oculusnoctis*, eudicotyledons are mainly represented by Fagaceae (most of *Tricol-popollenites* spp. and *Tricolporopollenites* spp., 40 pollen grains; 7% of eudicotyledon pollen), Myricaceae (*Triatriopollenites* spp., Fig. 4M; 30; 5.2%) and Cyrillaceae/Clethraceae (*Tricolporopollenites megaexactus*; Fig. 4N, 7; 1.2%).

The detailed level-by-level counting is available in Supplementary data 1 and detailed taxa plates in Supplementary data 2.

## 4.2. Environmental patterns

To reconstruct paleoenvironmental patterns we have used the taxa environmental affinity of Akkiraz (2008). First, we note a very high
<figure><img src="image_7.png" /><figcaption>**Fig. 3.** Bisaccate pollen and non-pollen palynomorphs (NPP) from the Bultu-Zile section. A-B: bisaccate pollen (Pinaceae). C: *Azolla* microspore massulae (Salvinaceae). D: *Ovoidites* (charophytes). E: *Botryococcus* (trebouxiales). F: fungi. G: structured vegetal debris. Scale: 10 µm.</figcaption></figure>

amount of swamp-freshwater taxa (1955, 55.8% of the non-bisaccate assemblage, 93.2% of the environment informative assemblage; Figs. 5-6). This assemblage includes mostly ferns (e.g. *Leiotriletes*, *Trilites*, *Triplanosporites*) and lycophytes, as well as *Inaperturopollenites* (Cupresaceae), *Corsinipollenites oculusnoctis* (Ludwigia), which are all indicators of swamp-freshwater environment. *Azolla* fern is also an indicator of calm swamp-freshwater environment (Barke et al., 2012).

Apart from this swamp-freshwater dominance, we note the presence of 98 lowland-riparian taxa (2.8% of the non-bisaccate assemblage,

4.7% of the environmental informative assemblage; Fig. 5). This environmental component is supported by the Cycadales, the different *Tricolporopollenites* species, *Tetracolporopollenites* spp. (Sapotaceae), most of the triporate pollen such as *Triatriopollenites* spp. (Myrica) and *Momipites* (*Engelhardia*, *Oreomunnea* or *Alfaroa*).

We also identified 45 montane pollen (1.3% of the non-bisaccate assemblage, 2.1% of the environmental informative assemblage; Fig. 5), which are *Zonalapollenites* (*Tsuga*) and most of the *Tricolpopollenites* species (mostly Fagaceae).
<caption>**Table 1**</caption>

Bultu-Zile counting summary. Environmental affinity according to Akkiraz (2008): SF: swamp-freshwater; LR: lowland-riparian; M: montane; ?: Unknown. Detailed level-by-level counting available in Supplementary data 2.

<table><thead><tr><th>Taxa</th><th>Botanical affinity</th><th>Environmental affinity</th><th>Number</th><th>Percentage among category</th><th>Percentage among total</th></tr></thead><tbody><tr><td colspan="6"><strong>Pteridophytes and lycophytes</strong></td></tr><tr><td>Leiotriletes sp. (Naumova, 1937) Potonié and Kremp, 1954</td><td>Pteridophyte</td><td>?</td><td>1395</td><td>60.18%</td><td>39.85%</td></tr><tr><td>Leiotriletes maxoides Krutzsch, 1962 maxoides Krutzsch, 1962</td><td>Lygodium japonicum (Lygodiaceae)</td><td>SF</td><td>5</td><td>0.22%</td><td>0.14%</td></tr><tr><td>Leiotriletes microlepioidites Krutzsch, 1962</td><td>Microlepia (Dennstaedtiaceae)</td><td>SF</td><td>1</td><td>0.04%</td><td>0.03%</td></tr><tr><td>Leiotriletes neddenlioides Krutzsch, 1962</td><td>Pteridophyte</td><td>SF</td><td>1</td><td>0.04%</td><td>0.03%</td></tr><tr><td>Triplanosporites sp. Pflug ex Thomson and Pflug, 1953</td><td>Pteridophyte</td><td>SF</td><td>143</td><td>6.17%</td><td>4.08%</td></tr><tr><td>Triplanosporites microsinuosus Pflanzl, 1955</td><td>Pteridophyte</td><td>SF</td><td>23</td><td>0.99%</td><td>0.66%</td></tr><tr><td>Triplanosporites sinuosus Pflug ex Thomson and Pflug, 1953</td><td>Pteridophyte</td><td>SF</td><td>4</td><td>0.17%</td><td>0.11%</td></tr><tr><td>Retitriletes sp. (Van der Hammen, 1956 ex Pierce, 1961) emend Döring et al., 1963</td><td>Lycopodium (Lycopodiaceae)</td><td>SF</td><td>182</td><td>7.85%</td><td>5.20%</td></tr><tr><td>Baculatisporites sp. Thomson and Pflug, 1953</td><td>Osmunda (Osmundaceae)</td><td>SF</td><td>38</td><td>1.64%</td><td>1.09%</td></tr><tr><td>Baculatisporites nanus (Wolff, 1934) Krutzsch, 1959</td><td>Osmunda (Osmundaceae)</td><td>SF</td><td>3</td><td>0.13%</td><td>0.09%</td></tr><tr><td>Cicatricosiporites sp. Potonié and Gelletich, 1933</td><td>Pteridophyte</td><td>SF</td><td>24</td><td>1.04%</td><td>0.69%</td></tr><tr><td>Trilites sp. Cookson, 1947</td><td>Pteridophyte</td><td>SF</td><td>178</td><td>7.68%</td><td>5.08%</td></tr><tr><td>Trilites multivallatus (Pflug in Thomson and Pflug, 1953) Krutzsch, 1959</td><td>Lygodium (Lygodiaceae)</td><td>SF</td><td>3</td><td>0.13%</td><td>0.09%</td></tr><tr><td>Trilites embriyonalis Krutzsch, 1967</td><td>Lygodiaceae</td><td>SF</td><td>1</td><td>0.04%</td><td>0.03%</td></tr><tr><td>Echinatisporis sp. Krutzsch, 1959</td><td>Selaginellaceae</td><td>SF</td><td>95</td><td>4.10%</td><td>2.71%</td></tr><tr><td>Polypodiaceoisporites sp. Potonié, 1956</td><td>Polypodiaceae, Pteris (Pteridaceae)</td><td>SF</td><td>118</td><td>5.09%</td><td>3.37%</td></tr><tr><td>Polypodiaceoisporites gracillimus Nagy, 1963</td><td>Pteridophyte</td><td>SF</td><td>1</td><td>0.04%</td><td>0.03%</td></tr><tr><td>Polypodiaceoisporites saxonicus Krutzsch, 1967</td><td>Pteris (Pteridaceae)</td><td>SF</td><td>1</td><td>0.04%</td><td>0.03%</td></tr><tr><td>Gleichenioides sp. Dettmann, 1963</td><td>Gleicheniaceae</td><td>SF</td><td>9</td><td>0.39%</td><td>0.26%</td></tr><tr><td>Laevigatosporites sp. Ibrahim, 1933</td><td>Pteridophyte</td><td>SF</td><td>32</td><td>1.38%</td><td>0.91%</td></tr><tr><td>Laevigatosporites gracilis Wilson and Webster, 1946</td><td>Pteridophyte</td><td>SF</td><td>3</td><td>0.13%</td><td>0.09%</td></tr><tr><td>Laevigatosporites haardti (Potonié and Venitz, 1934) Thomson and Pflug, 1953</td><td>Pteridophyte</td><td>SF</td><td>22</td><td>0.95%</td><td>0.63%</td></tr><tr><td>Laevigatosporites major Cookson, 1947 ex Krutzsch, 1959</td><td>Pteridophyte</td><td>SF</td><td>1</td><td>0.04%</td><td>0.03%</td></tr><tr><td>Verrucatosporites sp. Thomson and Pflug, 1953</td><td>Polypodiaceae</td><td>SF</td><td>1</td><td>0.04%</td><td>0.03%</td></tr><tr><td>Verrucatosporites favus (Potonié, 1931a) Thomson and Pflug, 1953</td><td>Dennstaedtiaceae</td><td>SF</td><td>6</td><td>0.26%</td><td>0.17%</td></tr><tr><td>Punctatosporites sp. Ibrahim, 1933</td><td>Pteridophyte</td><td>?</td><td>1</td><td>0.04%</td><td>0.03%</td></tr><tr><td>Hydrosporis levis Krutzsch, 1962</td><td>Salviniaceae</td><td>SF</td><td>27</td><td>1.16%</td><td>0.77%</td></tr><tr><td><strong>Total ferns and lycophytes</strong></td><td></td><td></td><td><strong>2318</strong></td><td></td><td><strong>66.21%</strong></td></tr><tr><td colspan="6"><strong>Non-bisaccate conifers</strong></td></tr><tr><td>Inaperturopollenites sp. Thomson and Pflug, 1953</td><td>Cupressaceae</td><td>SF</td><td>81</td><td>13.68%</td><td>2.31%</td></tr><tr><td>Inaperturopollenites dubius (Potonié and Venitz, 1934) Thomson and Pflug, 1953</td><td>Taxodium, Glyptostrobus (Cupressaceae)</td><td>SF</td><td>141</td><td>23.82%</td><td>4.03%</td></tr><tr><td>Inaperturopollenites magnus (Potonié, 1934) Thomson and Pflug, 1953</td><td>Taxodioideae (Cupressaceae)</td><td>SF</td><td>340</td><td>57.43%</td><td>9.71%</td></tr><tr><td>Zonalapollenites sp. Pflug, 1953</td><td>Tsuga (Pinaceae)</td><td>M</td><td>30</td><td>5.07%</td><td>0.86%</td></tr><tr><td><strong>Total non-bisaccate conifers</strong></td><td></td><td></td><td><strong>592</strong></td><td></td><td><strong>16.91%</strong></td></tr><tr><td colspan="6"><strong>Cycadophytes</strong></td></tr><tr><td>Cycadopites sp. Wodehouse ex Wilson and Webster, 1946</td><td>Cycadaceae</td><td>LR</td><td>9</td><td>69.23%</td><td>0.26%</td></tr><tr><td>Cycadopites lusaticus Krutzsch, 1970</td><td>Cycas? (Cycadaceae)</td><td>LR</td><td>4</td><td>30.77%</td><td>0.11%</td></tr><tr><td><strong>Total cycadophytes</strong></td><td></td><td></td><td><strong>13</strong></td><td></td><td><strong>0.37%</strong></td></tr><tr><td colspan="6"><strong>Monocotyledons</strong></td></tr><tr><td>Sparganiaceaeopollenites polygonalis Thiergart, 1937</td><td>Sparganiaceae</td><td>SF</td><td>3</td><td>/</td><td>0.09%</td></tr><tr><td colspan="6"><strong>Eudicotyledons</strong></td></tr><tr><td>Corsinipollenites oculusnoctis (Thiergart, 1940) Nakoman, 1965</td><td>Ludwigia (Onagraceae)</td><td>SF</td><td>468</td><td>81.39%</td><td>13.37%</td></tr><tr><td>Triatriopollenites rurensis Thomson and Pflug, 1953</td><td>Myrica (Myricaceae)</td><td>LR</td><td>27</td><td>4.70%</td><td>0.77%</td></tr><tr><td>Triatriopollenites bituitus (Potonié, 1931a) Thomson and Pflug, 1953</td><td>Myrica (Myricaceae)</td><td>LR</td><td>2</td><td>0.35%</td><td>0.06%</td></tr><tr><td>Triatriopollenites excelsus (Potonié, 1931a) minor Thomson and Pflug, 1953</td><td>Myricaceae</td><td>LR</td><td>1</td><td>0.17%</td><td>0.03%</td></tr><tr><td>Momipites punctatus (Potonié, 1931a) Nagy, 1969</td><td>Engelhardia, Oreomunnea, Alfaroa (Juglandaceae)</td><td>LR</td><td>3</td><td>0.52%</td><td>0.09%</td></tr><tr><td>Triporopollenites sp. Thomson and Pflug, 1953</td><td>?</td><td>LR</td><td>6</td><td>1.04%</td><td>0.17%</td></tr><tr><td>Labrapollis labraferus (Potonié, 1931b; Krutzsch, 1968)</td><td>Lythraceae</td><td>LR</td><td>2</td><td>0.35%</td><td>0.06%</td></tr><tr><td>Compositoipollenites sp. Potonié, 1960</td><td>Asteraceae</td><td>LR</td><td>1</td><td>0.17%</td><td>0.03%</td></tr><tr><td>Compositoipollenites rhizophorus (Potonié, 1934) Potonié; 1960 burghasungensis (Mürriger and Pflug, 1952) Thomson and Pflug, 1953</td><td>Icacinaceae</td><td>LR</td><td>1</td><td>0.17%</td><td>0.03%</td></tr><tr><td>Pentapollenites pentangulus (Thomson and Pflug, 1953) Krutzsch, 1957</td><td>?</td><td>LR</td><td>1</td><td>0.17%</td><td>0.03%</td></tr><tr><td>Tricolpopollenites sp. Thomson and Pflug, 1953</td><td>?</td><td>LR</td><td>2</td><td>0.35%</td><td>0.06%</td></tr><tr><td>Tricolpopollenites henrici (Potonié, 1931a) Thomson and Pflug, 1953</td><td>Quercus (evergreen; Fagaceae)</td><td>M</td><td>3</td><td>0.52%</td><td>0.09%</td></tr></tbody></table>

(continued on next page)
<table><caption>**Table 1 (continued)**</caption><thead><tr><th>Taxa</th><th>Botanical affinity</th><th>Environmental affinity</th><th>Number</th><th>Percentage among category</th><th>Percentage among total</th></tr></thead><tbody><tr><td>Tricolpopollenites liblarensis (Potonié et al., 1950) Thomson and Pflug, 1953 liblarensis (Potonié et al., 1950) Thomson and Pflug, 1953</td><td>Fagaceae</td><td>M</td><td>7</td><td>1.22%</td><td>0.20%</td></tr><tr><td>Tricolpopollenites microhenrici (Potonié, 1931c) Thomson and Pflug, 1953</td><td>Quercus (evergreen; Fagaceae)</td><td>M</td><td>5</td><td>0.87%</td><td>0.14%</td></tr><tr><td>Tricolpopollenites cingulum (Potonié, 1931c) Thomson and Pflug, 1953 fusus (Potonié, 1931c) Thomson and Pflug, 1953</td><td>Trigonobalanus (Fagaceae)</td><td>LR</td><td>1</td><td>0.17%</td><td>0.03%</td></tr><tr><td>Tricolpopollenites cingulum (Potonié, 1931c) Thomson and Pflug, 1953 pusillus (Potonié, 1934) Thomson and Pflug, 1953</td><td>Castanea, Castanopsis, Lithocarpus, Pasania (Fagaceae)</td><td>LR</td><td>8</td><td>1.39%</td><td>0.23%</td></tr><tr><td>Tricolpopollenites cingulum (Potonié, 1931c) Thomson and Pflug, 1953 oviformis (Potonié, 1931c) Thomson and Pflug, 1953</td><td>Castanea, Castanopsis, Lithocarpus, Pasania (Fagaceae)</td><td>LR</td><td>16</td><td>2.78%</td><td>0.46%</td></tr><tr><td>Tricolpopollenites megaexactus (Potonié, 1931c) Thomson and Pflug, 1953 bruhlensis (Potonié et al., 1950) Thomson and Pflug, 1953</td><td>Cyrillaceae, Clethraceae</td><td>LR</td><td>6</td><td>1.04%</td><td>0.17%</td></tr><tr><td>Tricolpopollenites megaexactus (Potonié, 1931c) Thomson and Pflug, 1953 exactus (Potonié, 1931c) Thomson and Pflug, 1953</td><td>Cyrillaceae, Clethraceae</td><td>LR</td><td>1</td><td>0.17%</td><td>0.03%</td></tr><tr><td>Tricolpopollenites marcodurensis Thomson and Pflug, 1953</td><td>Cissus, Parthenocissus (Vitaceae)</td><td>LR</td><td>1</td><td>0.17%</td><td>0.03%</td></tr><tr><td>Tricolpopollenites microreticulatus Thomson and Pflug, 1953</td><td>Oleaceae</td><td>LR</td><td>2</td><td>0.35%</td><td>0.06%</td></tr><tr><td>Tricolpopollenites oleoides Krutzsch and Vanhoorne, 1977</td><td>Armeria (Plumbaginaceae)</td><td>LR</td><td>1</td><td>0.17%</td><td>0.03%</td></tr><tr><td>Tricolpopollenites edmundi (Potonié, 1931c) Thomson and Pflug, 1953</td><td>Mastixiaceae</td><td>LR</td><td>2</td><td>0.35%</td><td>0.06%</td></tr><tr><td>Tricolpopollenites satzveyensis Thomson and Pflug, 1953</td><td>Mastixiaceae</td><td>LR</td><td>1</td><td>0.17%</td><td>0.03%</td></tr><tr><td>Retitricolpites sp. (Van der Hammen, 1956) Pierce, 1961</td><td>?</td><td>?</td><td>2</td><td>0.35%</td><td>0.06%</td></tr><tr><td>Ilexpollenites margaritatus (Potonié, 1931a) Thiergart, 1937 ex Potonié, 1960</td><td>Ilex (Aquifoliaceae)</td><td>LR</td><td>2</td><td>0.35%</td><td>0.06%</td></tr><tr><td>Tetracolpopollenites sapotoides Thomson and Pflug, 1953</td><td>Planchonella (Sapotaceae)</td><td>LR</td><td>1</td><td>0.17%</td><td>0.03%</td></tr><tr><td>Tetracolpopollenites obscurus Thomson and Pflug, 1953</td><td>Sapotaceae</td><td>LR</td><td>1</td><td>0.17%</td><td>0.03%</td></tr><tr><td>Polycolporites sp. Mehrotra, 1983</td><td>?</td><td>?</td><td>1</td><td>0.17%</td><td>0.03%</td></tr><tr><td>Total eudicotyledons</td><td>/</td><td>/</td><td>575</td><td>/</td><td>16.42%</td></tr><tr><td>TOTAL</td><td>/</td><td>/</td><td>3501</td><td>/</td><td></td></tr></tbody></table>

Importantly, we did not discover marine dinocysts and foraminiferal linings in the samples, and we did not find mangrove or back-mangrove taxa such as *Spinizonocolpites* (Nypa type palm), *Psilatricolporites crassus* (*Pelliciera*), *Proxapertites* (Araceae), and *Avicennia*. (Verbenaceae or Avicenniaceae) either.

The clustering analysis (Fig. 5A) highlights an environmental shift separating a lower and an upper section around the sample 23BZ2.07 (10.3 m above the base of the section). This sample is characterized by an unusually low swamp-freshwater component (44% of the assemblage). However, this anomaly can be explained by the unusually low number of sporomorphs in this sample (63), which is the only one containing fewer than 141 sporomorphs.

The NMDS ordination plot (Fig. 5B) confirms that the different samples are dominated by both swamp-freshwater and lowland-riparian components – confirming the environmental affinity proposed by Akkiraz (2008).

## 4.3. Climatic reconstruction

### 4.3.1. Coexistence Approach

The CA was applied to each Bultu-Zile sample based on 37 different taxa (Table 2). No incongruence was detected among the 19 different samples (see Supplementary data 4). *Tricolpopollenites oleoides* (Oleaceae) was particularly constraining in the initial CA analysis: six of the seven climatic parameters were limited at their maximum values by this species. Since *T. oleoides* was represented by only a single specimen, the CA was repeated without it.

Since the sporomorphs were deposited in a swamp-freshwater environment, typical non-angiosperm sporomorphs (e.g. fern spores and Cupressaceae pollen) were included in the analysis. The CA results based on angiosperms only (21 taxa) are very similar to those obtained

when all taxa are considered (Table 2). The two datasets differ only in MATmax (by 4.5 °C), CMTmax (by 3.0 °C), WMTmax (by 0.1 °C) and MPWETmax (by 101 mm).

Considering all taxa, we obtained a mean annual temperature (MAT) ranging from 17.2 to 21.9 °C, bounded at the lower end by *Trigonobalanus* (Fagaceae, *T. c. fusus*) and at the upper end by *Tsuga* (Pinaceae, *Zonalapollenites* sp.). The coldest month temperature (CMT) ranges from 9.6 to 15.6 °C, bounded at the lower end by Mastixiaceae (*T. edmundi* and *T. satzveyensis*) and *Microlepiia* (Dennstaedtiaceae, *Leio-triletes microlepioidites*), and at the upper end by *Tsuga* (Pinaceae, *Zonalapollenites* sp.). The warmest month temperature (WMT) ranges from 24 to 28.1 °C, bounded at the lower end by *Trigonobalanus* (Fagaceae, *T. c. fusus*) and at the upper end by *Azolla* sp. (Salviniaceae). The mean annual precipitation (MAP) ranges from 1,217 mm to 1,551 mm, bounded at the lower end by *Trigonobalanus* (Fagaceae, *T. c. fusus*) and at the upper end by *Cissus-Parthenocissus* (Vitaceae, *T. marcodur-ensis*). The mean precipitation of the wettest month (MPWET) ranges from 254 to 265 mm, bounded at the lower end by *Trigonobalanus* (Fagaceae, *T. c. fusus*) and at the upper end by *Taxodium-Glyptostrobus* (Cupressaceae, *Inaperturopollenites dubius*). The mean precipitation of the driest month (MPDRY) ranges from 34 to 51 mm, bounded at the lower end by *Planchonella* (Sapotaceae, *T. sapotoides*) and at the upper end by *Osmunda* (Osmundaceae, *Baculatisporites* sp. and *B. nanus*). And that of the warmest month (MPWARM) ranges from 120 to 214 mm, bounded at the lower end by *Trigonobalanus* (Fagaceae, *T. c. fusus*) and at the upper end by *Cissus-Parthenocissus* (Vitaceae, *T. marcodurensis*). These climatic parameters indicate a warm and wet temperate climate (subtropical). The important overlap between MPWET and MPWARM indicates that the wettest period of the year occurred in summer. According to the Köppen-Geiger classification, the climate corresponds to type Cfa (wet temperate with hot summer; Köppen, 1900; Geiger, 1954,
<figure><img src="image_8.png" /><figcaption>**Fig. 4.** Key sporomorph taxa from the Bultu-Zile section. A: *Hydrosporis levis* cluster. B: *Leiotriletes* sp. C: *Retitriletes* sp. D: *Polypodiaceoisporites* sp. E: *Verrucatosporites* sp. F: *Triplanosporites* sp. G: *Echinatisporis* sp. H: *Inaperturopollenites* sp. I: *Zonalapollenites* sp. J: *Sparganiaceae*pollenites polygonalis. K-L: *Corsinipollenites* oculusnoctis. M: *Triatriopollenites* rurensis. N: *Tricolporopollenites* megaexactus bruhlensis. Scale: 10 µm.</figcaption></figure>
<figure><img src="image_9.png" /><figcaption>**Fig. 5.** (A) Palynological summary diagram of Bultu-Zile section with cluster analysis based on CONISS in Tilia v3.0.3 (Grimm, 1987). Blue: swamp-freshwater indicators. Green: lowland-riparian indicators. Red: montane indicators. Depth in meters. (B) NMDS ordination plot of the 19 palynological samples from the Bultu-Zile section. Red: environment labels. Black: sample labels (depth in meters). Script and data are available in Supplementary data 3.</figcaption></figure>

<figure><img src="image_10.png" /><figcaption>**Fig. 6.** Reconstruction of the unique swamp-freshwater floral profile in Bultu-Zile and its area. *Azolla* and *Ludwigia* (enlarged) are new taxa for the Eocene of Türkiye.</figcaption></figure>

**Table 2**

Coexistence intervals of combined samples from Bultu-Zile flora. MAT: mean annual temperature (°C). CMT: coldest month temperature (°C). WMT: warmest month temperature (°C). MAP: mean annual precipitation (mm). MPWET: mean precipitation of the wettest month (mm). MPDRY: mean precipitation of the driest month (mm). MPWARM: mean precipitation of the warmest month (mm).

<table><thead><tr><th></th><th>MAT</th><th>CMT</th><th>WMT</th><th>MAP</th><th>MPWET</th><th>MPDRY</th><th>MPWARM</th><th>Taxa number</th></tr></thead><tbody><tr><td colspan="9"><strong>BULTU-ZILE COEXISTENCE DATA (ALL TAXA)</strong></td></tr><tr><td>Max</td><td>21.9 °C</td><td>15.6 °C</td><td>28.1 °C</td><td>1551 mm</td><td>265 mm</td><td>89 mm</td><td>214 mm</td><td>37</td></tr><tr><td>Min</td><td>17.2 °C</td><td>9.6 °C</td><td>24 °C</td><td>1217 mm</td><td>254 mm</td><td>34 mm</td><td>118 mm</td><td></td></tr><tr><td colspan="9"><strong>BULTU-ZILE COEXISTENCE DATA (ANGIOSPERMS ONLY)</strong></td></tr><tr><td>Max</td><td>26.4 °C</td><td>18.6 °C</td><td>28.2 °C</td><td>1551 mm</td><td>366 mm</td><td>89 mm</td><td>214 mm</td><td>21</td></tr><tr><td>Min</td><td>17.2 °C</td><td>9.6 °C</td><td>24 °C</td><td>1217 mm</td><td>254 mm</td><td>34 mm</td><td>118 mm</td><td></td></tr></tbody></table>

1961).

### 4.3.2. Crest

Results from CREST differ depending on the use of absence-presence
sporomorph counting or relative abundance (Table 3).

The CREST analysis based on absence-presence sporomorph counting yields a 95% confidence interval that is congruent with the CA results. However, the optima inferred from CREST suggest a somewhat colder (e.g. MAT of 15.2 °C compared to 17.2–21.9 °C) and drier climate (e.g. MAP of 1,132 mm compared 1,217–1,551 mm) than the CA. Nevertheless, the reconstruction still corresponds to a Cfa climate (wet temperate with hot summer) in the Köppen-Geiger classification (Köppen, 1900; Geiger, 1954, 1961). As observed in the CA results, the MPWET and MPWARQ values are consistent, supporting the conclusion that the wettest period of the year occurred in summer.

The CREST analysis based on relative abundances of the sporomorph counts yields a 95% confidence interval which partially overlaps with our CA results. The optima from this second CREST analysis are even colder (e.g. MAT of 10.8 °C) and drier (MAP of 813 mm) than those from the previous CREST analysis. They yet still fit with a Cfa climate.

The complete R script and data are available in Supplementary data 5.

# 5. Discussion

## 5.1. Paleoenvironmental reconstruction

All known palynofloras of the Balkanatolian Eocene (Table 4) were deposited at the end of a fluvial system. Consequently, their dominant environmental component is the mangrove (or back mangrove) vegetation. In contrast, the Bultu-Zile locality differs from these sites (e.g. Arabınköy, Çiçekdağı mine and Eski-Çeltek mine) by the absence of mangrove indicators such as *Nypa* palms (Arecaceae), *Avicennia* (Verbenaceae) and *Pelliciera* (Tetrameristaceae) (Akgün, 2002; Akgün et al., 2002; Akkiraz et al., 2008). Bultu-Zile also lacks back-mangrove indicators, including *Acrostichum aureum* (Pteridaceae), Ephedraceae, Araceae, *Mauritia* and other Arecaceae, and Restionaceae.

Therefore, the Bultu-Zile locality provides us with a unique insight into the first calm-freshwater (lacustrine or marshy) palynoflora (Fig. 6) documented among Balkanatolia endemic sites. This interpretation is supported by the high abundance and diversity of swamp-freshwater indicators, including several fern families (e.g. Gleicheniaceae, Polyodiaceae, Osmundaceae), Selaginellaceae, Cupressaceae conifers, and Sparganiaceae. In addition, Bultu-Zile yields freshwater indicators which were not previously recorded from the Eocene of Türkiye: *Azolla* ferns (Salviniaceae) and *Ludwigia* (Onagraceae). However, some taxa that have been documented in the Eocene of Türkiye do not occur at Bultu-Zile, including Nymphaceae, *Nyssa* (Nyssaceae), and *Crudia* (Fabaceae).

The lowland-riparian indicators discovered in Bultu-Zile are commonly known for the Eocene of Türkiye. In Bultu-Zile, we have found Cycadaceae, *Ilex* (Aquifoliaceae), Cyrillaceae-Clethraceae, *Castanea* (Fagaceae), *Icacinaceae*, Juglandaceae, Mastixiaceae, Myricaceae, *Armeria* (Plumbaginaceae), Sapotaceae. However, other lowland-riparian indicators from the Eocene of Türkiye are missing: *Sambucus* (Adoxaceae), *Anacardiaceae*, *Araliaceae*, *Alnus* and other Betulaceae, *Celtis* (Cannabaceae), *Corylaceae*, *Eucommia* (Eucommiaceae), *Myrtaceae*, *Platanus* (Platanaceae), *Rhamnaceae*, *Rutaceae*, *Poaceae*, *Salix* (Salicaceae), *Simaroubaceae*, *Ulmus* (Ulmaceae).

Bultu-Zile also presents a minority (1,3% of the non-bisaccate assemblage) montane indicators: Pinaceae, *Quercus* and other Fagaceae. But it lacks Symplocaceae.

As all the other Turkish floras of Balkanatolian age, Bultu-Zile also lacks Mediterranean xerophytes. This is congruent with our knowledge of the Proto-Irano-Turanian floristic region, which is assumed to reach Türkiye during the end of the Eocene or the beginning of the Oligocene (Manafzadeh et al., 2014, Manafzadeh et al., 2017). The Bultu-Zile flora thus confirms, along with the other localities (Table 4), that Mediterranean xerophytes were absent in the Lutetian of Türkiye.

The absence of mangrove and back-mangrove indicators, together with the overabundance of swamp-freshwater indicators, supports the interpretation that the Bultu-Zile ecosystem was located further inland than the previously described Lutetian paleofloras. The similar climatic reconstructions between Bultu-Zile and the Çankırı and Suluova basins (Fig. 7) suggest that Bultu-Zile was situated at a higher elevation – by at most a few hundred meters.

We note that two key taxa, *Azolla* (Salviniaceae) and *Corsinipollenites oculusnoctis* (Ludwigia), as yet have only been documented in Türkiye in younger strata and thus suggest a younger age for the locality. Indeed, *Azolla* is only documented in current Turkish floras (Gevrek, 2015), and *Corsinipollenites oculusnoctis* is only known for records of Oligocene age and younger (Akgün and Akyol, 1999; Kayseri and Akgün, 2008; Güvenli, 2015). However, outside of Türkiye both taxa are documented in localities older than Bultu-Zile: *Azolla* is known since the Cretaceous in the Americas (Hall, 1974; Hermsen et al., 2019) and in the early Eocene Arctic basin in Europe (Brinkhuis et al., 2006), whereas *Corsinipollenites* is known since the Paleocene in South America (Pocknall and Jarzen, 2009) and in the Middle Eocene of Eckfeld in Germany (Wilde and Frankenhäuser, 1998).

As both *Azolla* and *Corsinipollenites* are restricted to freshwater environments (Martins, 1866; Barke et al., 2012; Utescher et al., 2024) and as there is so far no described freshwater pollen assemblage in the Eocene of Türkiye, it is thus probable that their absence in previously studied Eocene localities of Türkiye is related to the depositional environment of these localities.

## 5.2. Remarks on CREST climatic reconstruction

Our CREST optimum results indicate lower values of temperature and precipitation compared to the CA results (see section 4.3). As the CA is non-probabilistic (Mosbrugger and Utescher, 1997), the derived coexistence intervals do not provide information about the actual climatic optima within those intervals, unlike CREST (Chevalier et al., 2014). However, we observe that the climatic optima obtained with

<caption>**Table 3**</caption>

CREST results on the Bultu-Zile Lutetian palynoflora (optimum values, 50% and 95% confidence intervals). MAT: mean annual temperature (°C). CQT: mean temperature of the coldest quarter (°C). WQT: mean temperature of the warmest quarter (°C). MTWET: mean temperature of the wettest quarter (°C). MAP: mean annual precipitation (mm). MPWET: mean precipitation of the wettest month (mm). MPDRY: mean precipitation of the driest month (mm). MPWARQ: mean precipitation of the warmest quarter (mm).

<table><thead><tr><th>Confidence intervals</th><th>MAT</th><th>CQT</th><th>WQT</th><th>MTWET</th><th>MAP</th><th>MPWET</th><th>MPDRY</th><th>MPWARQ</th><th>Taxa number</th></tr></thead><tbody><tr><td colspan="10"><strong>BULTU-ZILE CREST DATA (absence-presence)</strong></td></tr><tr><td>Optima</td><td>15.2 °C</td><td>4.7 °C</td><td>18.8 °C</td><td>21.9 °C</td><td>1132 mm</td><td>118 mm</td><td>47 mm</td><td>291 mm</td><td rowspan="3">36</td></tr><tr><td>50%</td><td>12.8—17.1</td><td>3.3—9.5</td><td>17.3—22.8</td><td>18.5—24.1</td><td>842—1339</td><td>92—183</td><td>36—63</td><td>199—398</td></tr><tr><td>95%</td><td>9.0—21.0</td><td>-0.9—16.2</td><td>15.6—27.4</td><td>11.4—28.2</td><td>528—2485</td><td>64—389</td><td>17—104</td><td>140—885</td></tr><tr><td colspan="10"><strong>BULTU-ZILE CREST DATA (relative abundance)</strong></td></tr><tr><td>Optima</td><td>10.8 °C</td><td>4 °C</td><td>17.8 °C</td><td>12.7 °C</td><td>813 mm</td><td>101 mm</td><td>45 mm</td><td>203 mm</td><td></td></tr><tr><td>50%</td><td>9.1—12.6</td><td>1.1—6.8</td><td>16.3—19.4</td><td>9.8—17.4</td><td>634—1092</td><td>75—128</td><td>34—59</td><td>158—287</td><td></td></tr><tr><td>95%</td><td>5.6—18.8</td><td>-6.0—13.7</td><td>13.6—25.8</td><td>5.9—26.3</td><td>329—2033</td><td>42—279</td><td>11—97</td><td>76—696</td><td></td></tr></tbody></table>
<table><caption>**Table 4**

Review of the fossil flora localities from the Ypresian to the Bartonian of Türkiye.</caption><thead><tr><th>Locality</th><th>Age</th><th>Mammal locality</th><th>Material</th><th>Mangrove</th><th>Back-mangrove</th><th>Swamp-freshwater</th><th>Lowland-Riparian</th><th>Montane</th><th>References</th></tr></thead><tbody><tr><td>Çorum-Bayat</td><td>early Eocene or Lutetian</td><td>No</td><td>Palyno.</td><td>No</td><td>Yes</td><td>Yes</td><td>Yes</td><td>No</td><td>(Akyol, 1980)</td></tr><tr><td>Çakıroğlu creek</td><td>late Ypresian to Lutetian</td><td>No</td><td>Palyno.</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>(Akkiraz et al., 2022)</td></tr><tr><td>Western part of Yozgat-Çiçekdağ and Sorgun area (including Çiçekdağı mine)</td><td>Lutetian</td><td>Yes</td><td>Palyno.</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>(Akgün et al., 2002; Akkiraz et al., 2008)</td></tr><tr><td>Arabınköy</td><td>Lutetian</td><td>Yes</td><td>Palyno.</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>(Akgün et al., 2002; Akkiraz et al., 2008)</td></tr><tr><td>Eastern part of Yozgat-Sorgun area</td><td>Lutetian</td><td>No</td><td>Palyno.</td><td>Yes</td><td>No</td><td>Yes</td><td>Yes</td><td>Yes</td><td>(Nakoman, 1966)</td></tr><tr><td>Eski-Çeltek mine</td><td>Lutetian</td><td>Yes</td><td>Palyno.</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>(Akgün, 2002; Akkiraz et al., 2008)</td></tr><tr><td>Mengen Coal Basin</td><td>Lutetian to Bartonian</td><td>No</td><td>Palyno.</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>No</td><td>(Durak et al., 2025)</td></tr><tr><td>Denizli- Başçeşme</td><td>Lutetian or Bartonian to Priabonian</td><td>No</td><td>Palyno.</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>(Akkiraz et al., 2006)</td></tr><tr><td>Burdur Basin</td><td>Lutetian or Bartonian to Priabonian</td><td>No</td><td>Palyno.</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>(Akkiraz, 2008; Toker et al., 2012)</td></tr><tr><td>Ankara-Çubuk-Susuzköy</td><td>middle Eocene</td><td>No</td><td>Phytoliths</td><td>Woodland or forest with abundant bamboos</td><td></td><td></td><td></td><td></td><td>(Strömberg et al., 2007)</td></tr><tr><td>Sarıkaya</td><td>Lutetian</td><td>No</td><td>Leaves + wood</td><td>Tropical-subtropical forest</td><td></td><td></td><td></td><td></td><td>(Akkemik et al., 2021; Akkemik et al., 2023a, 2023b; Akkemik et al., 2025)</td></tr></tbody></table>

CREST are often not centred within the 95% confidence intervals. This attenuation of climatic parameter values in CREST, compared to the CA, has already been documented in other regions (Gibson et al., 2022).

Our CREST results when using pollen relative abundance indicate lower values of temperature and precipitation than when using absence-presence pollen counting (see section 4.3). This may be due to the fact that palynological proportions do not accurately reflect the actual proportions of plant taxa in the environment (Davis, 1963). As a result, the CREST analysis based on relative abundance tends to overweight taxa that are overrepresented in the pollen assemblage, even if these taxa are not the most common in the local flora. In the case of Bultu-Zile, *Ludwigia* and several fern taxa – which dominate the pollen assemblage – appear to be associated with colder climatic conditions than the rarer taxa. Cupressaceae – also abundant in the Bultu-Zile assemblage – seem to prefer drier conditions than the other taxa. This may be due to the ecological diversity within Cupressaceae, which include both swamp-adapted species (e.g. *Taxodium distichum*) and desert-adapted ones (e. g. *Cupressus dupreziana*; Camus, 1926; Conner et al., 1986). Therefore, in the remainder of this manuscript we only discuss the CREST results derived from absence-presence sporomorph counting.

### 5.3. Ecosystems of the Lutetian in Balkanatolia

The Bultu Zile site, characterized by a swamp-freshwater habitat, represents one of the first documented occurrences of embrithopods outside a mangrove-dominated ecosystem. In Balkanatolia, embrithopod remains have also been reported from in paleosols and fluvial channels in the Orhaniye Basin (Maas et al., 1998; Licht et al., 2017). Embrithopods were previously interpreted as mangrove inhabitants, based on the depositional environments in which their fossils were recovered (Sen and Heintz, 1979). These two sites indicate that embrithopod regularly ventured beyond the Neotethyan coastal wetlands and does not contradict a terrestrial behaviour.

Excluding its distinctive freshwater signature, the Bultu-Zile flora shows strong similarities with other Lutetian pollen localities of Balkanatolia (Table 4), allowing a synthetic reconstruction of their ecosystems. The Lutetian paleofloras of Balkanatolia were dominated by

evergreen broad-leaved forests, associated with fern- and Cupressaceae-rich swamps, as well as mangrove and back-mangrove communities along the shoreline. The corresponding climate was wet temperate with hot and wet summers mimicking monsoonal rainfall (as suggested by Licht et al., 2017), and appears to have been relatively homogeneous across Lutetian mammal-bearing localities (Fig. 7). Both the CA and CREST-based reconstructions for these sites show substantial overlap.

These reconstructions can be compared with the Lutetian ecosystems of biogeographic provinces located east and west of Balkanatolia along the Neotethyan shorelines. To the west, in the southwestern Europe, the Iberian paleofloras are characterized by several fern families (e.g. Schizaceae), Cupressaceae, *Nypa* palms, *Nyssa*, and Juglandaceae (Postigo Mijarra et al., 2009; Kvacek, 2010). These taxa are also documented in Balkanatolia at the same interval and correspond to back-mangrove, swamp-freshwater and evergreen broad-leaved forest environments. In the Paris basin, several environmental components have been identified, including mangroves (e.g. *Avicennia*), back-mangroves (e.g. *Nypa*), swamp-freshwater (e.g. Characeae, Nymphaceae), evergreen seasonal forests (e.g. *Nerium*, Euphorbiaceae) and evergreen broad-leaved forests (e.g. Juglandaceae, Fagaceae; De Franceschi, 2009). Geochemical climatic reconstructions from the Lutetian Paris Basin (Huyghe et al., 2012) indicate a warm temperate climate with marked seasonality, with sea-surface mean annual temperature (MAT) between 15 and 23 °C and warmest months temperatures (WMT) between 22 and 30 °C. In Messel (Lutetian of Germany), the vegetation represents an evergreen broad-leaved forest dominated by evergreen Fagaceae and Juglandaceae, together with Sapotaceae, Mastixiaceae, and Icacinaceae (Lenz and Wilde, 2018). Palynological data from the locality indicate an orbitally-controlled alternation between warm-wet temperate and tropical conditions (Lenz et al., 2015).

A summer wet season for the Lutetian of Europe and Balkanatolia is shown in climate simulations with late middle Eocene climate boundary conditions (Van Horebeek et al., 2025). They show a seasonal weakening of the westerly winds blowing over the mid latitudes, enabling the set-up of a summer low pressure zone over Europe that enhance intense, convective rainfall mimicking monsoonal rainfall distribution.

In Central Asia, the southernmost Lutetian paleofloras are
<figure><img src="image_11.png" /><figcaption>**Fig. 7.** Comparison of CA (red) and CREST (green) climatic reconstructions in Bultu-Zile, Yozgat-Çiçekdağ, Yozgat-Sorgun, Eski-Çeltek. A: mean annual temperature (MAT). B: mean annual precipitation (MAP). CREST: the black line corresponds to the optimum, the dark green to the 50% confidence interval and the light green to the 90% confidence interval.</figcaption></figure>

documented from Kazakhstan (Akhmetiev and Zaporozhets, 2014). Blyakhova et al. (1971) described a Lutetian palynoflora dominated by evergreen Fagaceae (e.g. *Quercus* and *Castanopsis*). In the Pavlodar-Irtysh region, Makulbekov (1972) reported macroremains mainly of *Castanopsis*, along with other evergreen forest taxa (e.g. *Quercus*, *Lauraceae*, *Myrica*, *Podocarpus*), and fragmentary palm leaves indicative of back-mangrove environments. In the Zaisan Depression near Mount Kiin-Kerish, Romanova (1974) and Il'inskaya (1986) described macrofloras including *Liquidambar* (Altingiaceae), *Ficus* (Moraceae), *Dryophyllum* (Nothofagaceae), *Coccoloba* (Polygonaceae), *Idesia* (Flacourtiaceae), *Populus* (Salicaceae), *Sterculia* (Malvaceae), *Cassia* (Caesalpiniaceae), *Eugenia* (Myrtaceae), *Rhus* (Rhutaceae), *Sapindus* and *Ungnadia* (Sapindaceae), and *Phragmites* (Poaceae). *Akhmetiev and Zaporozhets* (2014) interpreted the Lutetian paleoflora as indicative of a monsoon-type climate. Other paleofloras from the Zaisan Depression were described by *Akhmetiev* (1985), including *Osmunda* (Osmundaceae), *Salvinia* (Salviniaceae), “Hibiscus” (Malvaceae), *Populus* (Salicaceae), Fabaceae, *Ulmus* (Ulmaceae), *Ailanthus* (Simaroubaceae), *Liquidambar* (Altingiaceae), *Celtis* (Cannabaceae), *Magnolia* (Magnoliaceae), *Comptonia* (Myricaceae), *Lindera*, *Neolitsea* and *Lindera* (Lauraceae), *Rutaceites* (Rhutaceae), *Ungnadia* (Sapindaceae), *Alnus* (Betulaceae), *Dyophyllum* (Nothofagaceae) and *Nitophyllites*. As in previous cases, this flora is consistent with a warm and humid climate (monsoon-like) climate.

Altogether, these data indicate an overall continuity of ecosystems along the Neotethyan margin from Western Europe to Central Asia

through Balkanatolia, although each of these regions displays local variations in their floral assemblages. The coastal zones were all characterized by similar mangrove and back-mangrove taxa (e.g. *Avicennia*, *Nypa*), while inland areas are dominated by warm and humid evergreen forest taxa (e.g. Fagaceae, Juglandaceae, Sapotaceae, Mastixiaceae, Myricaceae, Sapindaceae) and swamp-freshwater assemblages (e.g. Salviniaceae, Schizaceae, Osmundaceae, Nymphaceae). These floras collectively indicate a seasonal, warm-humid climate with hot and wet summers, though the monsoonal signature of this seasonality remains to be shown (Licht et al., 2017). This pattern does not support the existence of a strong climatic or environmental barrier among the three Eurasian biogeographic provinces (Stehlin, 1909; Licht et al., 2022) as an explanation for Balkanatolian faunal endemism. Instead, the persistence of this endemism appears more consistent with the geographic isolation of Balkanatolia (Métais et al., 2018).

### 5.4. The end of the Lutetian Balkanatolian ecosystems: A trigger for the end of Balkanatolian endemism?

Post-Lutetian Eocene ecosystems of Balkanatolia, synchronous with the decline and extinction of the endemic fauna, remain poorly documented, and it is unclear how long their relative stability lasted after the end of the Lutetian. Only a few Balkanatolian paleofloras of Bartonian and Priabonian age are known, with ages poorly constrained between the latest Eocene and earliest Oligocene: the Zeyvegediği-Kabaktepe flora (Akgün et al., 2021) and the Mersin-Mut flora (Kayseri et al.,
2006). These paleofloras do not appear to differ substantially from earlier assemblages, although the Zeyvegediği-Kabaktepe flora indicates the emergence of mid-altitude forest and steppe environments (Akgün et al., 2021). The inferred climate is broadly consistent with that reconstructed for Bultu-Zile, although minimum temperature estimates are less well constrained at the younger locality. In contrast, the Mersin-Mut lower mean annual temperature (MAT) and coldest month temperature (CMT), but not warmest month temperature (WMT), relative to Bultu-Zile (Kayseri-Özer, 2013), points to a cooling and an increased seasonality during the latest Eocene or earliest Oligocene. Finally, the early Oligocene remained characterized by a warm temperate climate (evidenced by the presence of *Nypa* palms and *Pelliciera* mangroves), although conditions became progressively cooler as the Oligocene advanced (Akgün et al., 2013).

In Iberia, the global trend toward a colder and more arid climate led to the regional extinction of mangrove vegetation, which was replaced during the Bartonian-Priabonian by taxa characteristic of more open environments, such as Ephedraceae and Chenopodiaceae (*Cavagnetto and Anadón, 1996; Postigo Mijarra et al., 2009*). From the Priabonian to the early Oligocene, aridification and cooling intensified, as indicated by the appearance of *Acacia* and dry-climate-adapted Cupressaceae (*Cavagnetto and Guinet, 1994; Cavagnetto and Anadón, 1996; Postigo Mijarra et al., 2009*). In southern Central Asia, a comparable cooling and aridification event occurred during the late Lutetian or Bartonian, when *Quercus-Laurus* forests were replaced by sclerophyllous arboreal-frutescent maquis (*Akhmetiev and Zaporozhets, 2014*). The Oligocene is marked by the expansion of temperate deciduous and mesophyllous coniferous-broad-leaved forests (*Akhmetiev and Zaporozhets, 2014*).

Both western Europe and central Asia thus experienced an opening of their environments and the emergence of sclerophyllous vegetation as early as the latest Lutetian or the Bartonian-Priabonian (Pound and Salzmann, 2017; Semmani et al., 2024). This transition appears to have been delayed until the Early Oligocene in Balkanatolia, although the dating of the available localities remains poorly constrained. Until better age constraints become available for these localities and new Bartonian pollen assemblages are described, the Balkanatolian faunal turnover that occurred during the late Middle Eocene (Licht et al., 2022) will be difficult to associate with any specific paleoenvironmental trigger. Therefore, the proposed Bartonian-Priabonian opening, aridification, and cooling of Balkanatolia remain hypothetical.

## 6. Conclusion

Bultu-Zile represents a unique freshwater-deposited palynoflora from the Middle Eocene of Türkiye. Sporomorph counting reveals a significant proportion of fern spores, along with Cupressaceae and charophyte spores, all indicative of freshwater environments. Lowland-riparian and montane vegetations are also represented by various angiosperms, including Fagaceae, Myricaceae, Cyrillaceae/Clethraceae, Juglandaceae, Mastixiaceae, Lythraceae, Sapotaceae, *Ilex, Armeria*, Icacinaceae, and *Vitaceae*. Bultu-Zile thus provides the first evidence of embrithopod mammals in swamp-freshwater environments. This unique depositional environment explain the occurrence of two taxa newly reported from the Eocene of Türkiye: *Azolla* fern and *Corsinipollenites oculusnoctis* (*Ludwigia*, Onagraceae), both indicators of freshwater environments.

Both the CA and CREST reconstructions indicate a wet temperate with warm and wet summers climate for the Lutetian of Bultu-Zile. These results are consistent with evidence from other Balkanatolian mammal-bearing localities (e.g. the nearby Çankırı and Suluova basins), as well as with other known Lutetian palynofloras from the region. During the Lutetian, southern Eurasia appears to have experienced a relatively continuous warm-wet temperate with hot and wet summers climate, accompanied by evergreen Fagaceae and Juglandaceae forests and mangrove along the shoreline, extending from Western Europe through Balkanatolia to Central Asia. This pattern suggests that

Balkanatolian faunal endemism was not driven by a strong climatic or environmental heterogeneity.

By analogy with the Eocene-Oligocene faunal turnover in Western Europe, we suggest that the extinction of Balkanatolian endemic faunas during the Bartonian-Priabonian might have been caused by a combination of competition with the incoming Asia-derived mammals and environmental stress related to climatic cooling, aridification, and the opening of the environments – an ecosystemic change that appears to have started roughly simultaneously in Balkanatolia, Western Europe and Central Asia, between the Late Lutetian and the early Oligocene. However, Balkanatolian paleofloras from the critical Bartonian-Priabonian interval remain poorly documented and imprecisely dated. To better constrain the environments and climate of Balkanatolian during the Middle and Late Eocene, we emphasize the need to refine the chronological framework of known paleofloras (e.g. through geochronological dating) and to discover and analyze new Bartonian-Priabonian assemblages.

## CRediT authorship contribution statement

**Benjamin Raynaud:** Writing – review & editing, Writing – original draft, Visualization, Investigation, Formal analysis, Conceptualization. **M.Serkan Akkiraz:** Writing – review & editing, Validation, Supervision, Conceptualization. **Anaís Boura:** Writing – review & editing, Validation, Supervision, Conceptualization. **Carina Hoorn:** Writing – review & editing, Validation, Supervision, Conceptualization. **Martha Gibson:** Writing – review & editing, Formal analysis. **Adele Giobbini:** Writing – review & editing, Investigation. **Paul Botté:** Writing – review & editing. **Leny Montheil:** Writing – review & editing. **Mustafa Kaya:** Writing – review & editing. **Faruk Ocakoğlu:** Writing – review & editing. **Deniz İbilioğlu:** Writing – review & editing. **Grégoire Métais:** Writing – review & editing, Funding acquisition. **K.Christopher Beard:** Writing – review & editing, Funding acquisition. **Pauline Coster:** Writing – review & editing. **Alexis Licht:** Writing – review & editing, Validation, Supervision, Project administration, Funding acquisition, Conceptualization.

## Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

## Acknowledgements

We thank Hasan Can (Direnç Jeolojik Danışmanlık, Türkiye) for the pollen extraction. We also thank Cyril Willig (assistant engineer, CEMIM, MNHN, France) and all the CEMIM team (MNHN, France) for their help on the NanoZoomer S60 Digital slide scanner. We thank Helanlin Xiang (PhD student, IBED, University of Amsterdam, Netherlands) and Hanna van den Hil (MSc student, IBED, University of Amsterdam, Netherlands) for their help with the NMDS analysis. We thank Elodie Gazquez (communication manager, CEREGE, France) for her work on Fig. 6. Finally, we thank Vincent Lebreton (professor, HNHP, MNHN, France), Lionel Dubost (technician, HNHP, MNHN, France) and Rafael Cabral (PhD student, HNHP, MNHN, France) for having giving us the access to their microscope photography material. This work was supported by grants from the U.S. National Science Foundation, United States (EAR-1543684 and EAR-2141115) to KCB, National Geographic Society, United States (CRE GRANT #9215-12) to GM, and the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 101043268) to AL.

## Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi.
org/10.1016/j.jseaes.2026.106980.

## Data availability

We have attached our dataset in the Supplementary material depository.

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