Plant macrofossils from Hungarian Pleistocene II. Angiospermatophyta in GyŐrújfalu, West Hungary*

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1 ANNALES HISTORICO-NATURALES MUSEI NATIONALIS HUNGARICI Volume 88. Budapest, 1996 pp Plant macrofossils from Hungarian Pleistocene II. Angiospermatophyta in GyŐrújfalu, West Hungary* J. BAJZÁTH Department of Botany, Hungarian Natural History Museum H-1087 Budapest, Könyves Kálmán krî. 40, Hungary BAJZÁTH, J. (1996): Plant macrofossils from Hungarian Pleistocene 11. Angiospermatophyta in GyŐrújfalu, West Hungary. - Annls hist.-nat. Mus. natn. hung. 88: Abstract - A great number of plant-remains was found in the gravel-pit near GyŐrújfalu between 20 and 35 metres depth. The age of this assemblage according to the bioslratigraphy of the vertebrates and molluscs is Günz-Mindel (Cromer) interglacial. Among these fossil plants there are tree trunks, cones and seeds of gymnosperms, fruits and seeds of angiosperms and oospores of Characeae. The taxa of angiosperms are mainly herbaceous, aquatic or wetland species. In the assemblage the seeds of Potamogeton, Carex, Ranunculus and oospores of Characeae species dominated. Nine different plant communities could be distinguished by the macrofossils. Almost whole vegetation succession of the filling backwater is reconstructed from the communities. With 26 figures. INTRODUCTION In a previous paper (BAJZÁTH 1995) an important and unique locality of the Hungarian Lower Pleistocene (Günz-Mindel, Cromer interglacial) was reported. The first results of the palaeobotanical investigation were given in that publication. This year the study of gymnosperms was completed with examinations of the angiosperms and the other plant macrofossils. Here follows a general description of the macrofossils (fruits and seeds) which were found in the fluvial deposit in 20 m depth. The greyish, calcareous sand layer, between 20 m and 30 m, contains big clay lenses and silt lenses. The clay boulders I found in the deposit have two types: one is blackish with more humified peat fragments; it contained more fruit- and seed-fossils than the other type which was brown and peaty. In the brown clay the mineral parts were mixed with fragments of leaves and stems, small pieces of trees and seeds. To start the present investigation with I examined the macrofossils found in the clay lens. Having washed through the sieve sequences, I found a great number of macrofossils. 38 taxa of the angiosperms could be determined exactly. In addition three types of the oospores of Characeae were found: Nitellopsis obtusa, Cham sp., Nitella sp. These macrofossils were very well preserved, slightly charred and more or less whole so their identification at low taxonomic level was possible and easier. * Plant macrofossils from Hungarian Pleistocene I. Gymnospermatophyta in Győrújfalu, West Hungary

2 SYSTEMATIC DESCRIPTIONS ANGIOSPERMATOPHYTA Alismataceae Alisma plantago-aquatica LINNAEUS, 1753 Description: The measures of the two whole fruit are 2.5 mm x 1.75 mm. The fruits are obovate and flattened. The base is slightly tapering and plucked out. The pericarps were contiguous with the seed. The seeds are little, mm in length and 0.8 mm in width. Discussion: The exact determination of this species is based on the identification of the fruits. Among the fossils there were two opening fruits and the seeds were seen. This species is very abundant in different interglacials and occurs in the glacials too. Sagittaria sagittifolia LINNAEUS, 1753 Description: The seeds are mm in length and 1.25 mm in width. The shape is horseshoe-like. Discussion: It is very similar to Alisma species, but Sagittaria is longer and the two stems of the seeds are not the same size. It is widespread in the Pleistocene deposits in Europe. Hydrocharitaceae Hydrocharis morsus-ranae LINNAEUS, 1753 Description: Small, obovate and fine seed 0.4 mm long and 0.25 mm in width. The surface of this specimen is very characteristically reticulate. The base and the summit of the seed is tapering. D i s c u s s i o n: This species is a typically intcrglacial aquatic plant. There were no remains in the glacial deposits in Europe (MAI & WALTHER 1988). Stratiotes aloides LINNAEUS, 1753 Description: The whole seeds are 8.5 mm x 2.3 mm in size. It is long-obovate. Its wall is smooth and a little ornamented with ridges. Discussion: This surviving species represents alone the Stratiotes genus. The water aloe genus has an interesting history which extends far back into the Tertiary. All records of the Stratiotes aloides are of interglacial age. It is another typical interglacial plant which indicates (with Hydrocharis) the true interglacial assemblage (GODWIN 1956). Potamogetonaceae Potamogeton perfoliatus LINNAEUS, 1753 (Figs 3^4) Description: This large specimen is mm x mm in size. From lateral view the endocarps are S-shaped or convex. Most of them have a short (0.5 mm long), broad-based beak (Figs 3-4). Discussion: The size and the shape shows great variation. A ALTO (1970) gave the detailed keys to distinguish the Potamogeton species. According to the literature this species is rare in

3 the interglacial deposits but abundant in the sediments of the Late-Glacial period in Central and West Europe. Potamogeton gramineus LINNAEUS, 1753 (Fig. 5) Description: The small endocarps are mm long and mm wide, more or less rounded. There is a very short beak on the top of the endocarp (Fig. 5). Discussion: This species is very remarkable in the interglacial (i. e. Cromer) deposits in Europe but it occurs in the glacial and Late-Glacial phases too. Najadaceae Najas tenuissima (A. BR.) MAGNUS, 1870 Description: The single broken seed is 1.75 mm in length and 0.5 mm in width. The shape is long obovate. The cells of the wall are long, more or less quadrangulate and thick. Discussion: This species is the modern form of the Najas lanceolata C. et E. M. REID which existed in Tertiary in West Europe and in Baskiria (DOROFEEV 1966). Cyperaceae Carex aquatilis WAHLENBERG Description: The achenes arc rounded-obovate 1.8 mm in length and 1.5 mm in width. Toward the base they are tapering. The beak is short. Discussion: It does not exist in modern Hungarian flora. Carex gracilis CURTIS, 1783 Description: The achenes are fine and small with short beak. The shape is elliptic or rounded; 1.5 mm in length and 0.8 mm in width. Carex caespitosa LINNAEUS, 1753 Description: The achenes are rather rounded mm x mm in size. The base of the seeds is thick. D i s c u s s i o n : It is known in Pliocene and Pleistocene localities in Europe. It is a relic species in the modern Hungarian flora. Carex elata ALLIONI, 1785 (Figs 17-18) Description: The relatively large achenes are mm in length and mm in width with short beak. The shape is obovate. The base of the seeds is thick and broad. The remains of the utriculus often stay on the base (Figs ). D i s c u s s i o n : It is a very characteristic species in a similar shape-range. This species is common in the Pleistocene in Europe. Carex elongata LINNAEUS, 1753 D e s c r i p t i o n: The characteristic long ovate achenes are mm in length and mm in width. There is a relatively long beak on the top of the seeds. Discussion: This Carex species indicates the existence of the alder forest. Carex nigra (LINNAEUS) REICHARD, 1778 Description: The achenes are mm mm in size. The shape is elliptic. Discussion: It is very similar to C. elata. It was found in Pliocene and Pleistocene in Europe.

4 Figs Seeds of Angiospermatophyta from GyŐrújfalu. 1-2 = Butomus umbellatus, 3-4 = Potamogeton perfoliatus, 5 = Potamogeton gramineits, 6-7 = Ranunculus lingua, 8-9 = Stachys palustris, = Oenanthe aquatica, 12 = Thalictrumflavum, 13 = Ranunculus aquatilis

5 Figs Seeds of Angiospermatophyta from GyŐrújfalu. 14 = Carex pseudocyperus, 15 = Carex riparia, 16 = Schoenoplectus lacuslris = Carex elata, = Carex rostrata

6 Carex pseudocyperus LINNAEUS, 1753 (Fig. 14) Description: The achenes are 2.5 mm in length and 1.75 mm in width with 0.5 mm long beak. The shape is triangulate and elliptic. Toward the summit and the base it is tapering (Fig 14). Discussion: This species occurred more or less continuously from the Pliocene in Europe. Carex riparia CURTIS, 1783 (Fig. 15) Description: The achenes are mm x mm in size with short, 0.2 mm beak. The shape is triangulate and elliptic. The shoulder of the achenes is angulate (Fig 15). Discussion: It occurred in the Pliocene and in the Pleistocene interglacial deposits in Europe. Carex rostrata STOKES, 1787 (Figs 19-20) Description: The achenes are mm in length and mm in width with 0.8 mm long beak. The shape is triangulate and obovate (Figs 19-20). Discussion: It is very common fossil in Quaternary deposits but in the interglacials it is more frequent in Europe. Carex sp. Description: The achenes are in their utriculus. The length is mm, the width is mm. The fruits are charred, with short beak. The shape is obovate-rounded. The base of the achenes is strong. They are not flattened. Discussion: These fruits are very similar to the C. data-type. Schoenoplectus lacustris (LINNAEUS) PALLA, 1888 (Fig. 16) Description: The measure of achene is 3.1 mm x 2 mm. The shape of the achene is amphora-like (Fig 16). Discussion: This species is very common in the Pleistocene interglacial deposits in Europe. Schoenoplectus tabernaemontani (C. C. GMELIN) PALLA, 1888 Description: The rounded obovate achenes with beak are mm long and mm wide. Discussion: Like Schoenoplectus lacustris this species is common in Europe but scarce in the Pleistocene interglacial and Late-Glacial layers. Scirpus sylvaticus LINNAEUS, 1753 Description: The very flattened but triangulate, fragile, small achenes arc mm long and 1 mm wide. The summit and the base are cuneate. Discussion: This species was already reported from the Middle Miocene in Poland (LANCUCKA-SRODONOWA 1966). In the Pleistocene it occurred in the interglacial layers in Europe. Scirpus sp. Description: The achenes are mm long and 1 mm in width. The shape is long obovate. Toward the strong base their shape are tapering and cuneate. The achenes are charred. Discussion: It is very similar to Dulichium marginatum (C. et E. M. REID) DOROFEEV, 1963 but the stalk of Scirpus sp. is broader.

7 Lemnaceae Lemna trisulca LINNAEUS, 1753 Description:A very small species is mm long and mm wide. The shape is angulate-rounded. The wall of the seed is deeply ribbed. Discussion: This species was found only in the Pliocene and Pleistocene interglacial deposits in Europe. Sparganiaceae Sparganium emersum REHMANN, 1872 Description: They are relatively large mm long and mm wide. The shape is elliptical, tapering toward the base without stalk. There are very fine stripes on the seeds. Discussion: It has been recorded from the Miocene. It was also found in the Pleistocene, mainly in the interglacial deposits. Typhaceae Typha cf. latifolia LINNAEUS Description: The small and fragile seed is 1.6 mm x 0.4 mm in size. The wall is transparent and slightly reticulate. Discussion: This species ranges from the Pliocene till the Present. It is very common in all stages of the Pleistocene in Europe. Butomaceae Butomus umbellatus LINNAEUS, 1753 (Figs 1-2) Description: The seeds are mm in length and 0.5 mm in width. 6-7 sharp, pearl-like ribs run from the top to the base of the seed (Figs 1-2). D i s c u s s i o n : It is known from the Pliocene but mainly its pollen grains were found in Europe. Ranunculaceae Ranunculus aquatilis LINNAEUS, 1753 (Fig. 13) Description: The fruits are mm x mm in size. The shape is ovalrounded. Several cross-lines run around the wall of the nut (Fig. 13). Discussion: It is a very common, pioneer species. Its fossils were found from the Late Pliocene. In the Pleistocene the European aquatic Ranunculus species (see below) occurred mainly in the interglacials and the Late-Glacial. Ranunculus fluitans LAMARCK, 1778 Description: The measures of the fruits are between mm and mm. The shape is broad-rounded. Several cross-lines run around the wall of the nut. Discussion: It seems to be very similar to R. aquatilis but the run of the wall is different. This species is known in Pleistocene deposits. Nowadays in Hungary there is only one locality where it occurs (Szigetköz, NW Hungary).

8 Ranunculus trichophylliis CHAIX, 1786 Description: The achenes are mm in length and mm in width. The shape is obovate and tapering toward the base. Ranunculus lingua LINNAEUS, 1753 (Figs 6-7) Description: The fruits are obovate with tapering summit. The measures are mm x mm (Figs 6-7). Discussion: This Ranunculus species is very common in the interglacial deposits in Europe, mainly in the Cromerien complex (GODWIN 1956). Ranunculus nemorosus A. P. DE CANDOLLE Description: The achene is 2.6 mm x 1.8 mm in size, rounded with tapering base. Discussion: This species is not known in modern Hungarian flora. It was found in the Cromer interglacial in the British Isles. Thalictrum flavum LINNAEUS (Fig. 12) Description: The fruits arc mm in length and mm in width. The shape is oval. There are 9-10 characteristic, deep ribs on the fruits (Fig. 12). Discussion: This well preserved species indicates the wet, swamp habitat which is very favourable for the fossilisation. Bctulaceae Alnus sp. Description: The naked axis of the fruit is 5.75 mm in length and 3.5 mm in width. Around the axis there are the cyclic remains of the seed-scales. Discussion: It could not be identified on a lower taxonomic level, because there were no nutlets among the fossils. Carpinus betulus LINNAEUS, 1753 Description: The nut is rounded triangulate in shape. There are three ribs on one side. Discussion: It is known from the Upper Pliocene in Europe. This species indicates the climatic characteristics during the Pleistocene. It occurred in the interglacial deposits. Polygonaceae Polygonum lapalhiidlium LINNAEUS, 1753 Description: The rounded achene is relatively large. Discussion: In the history of the vegetation this species has been connected mainly with human activity in Europe. The appearance in the Pleistocene deposits shows its natural habitat. Haloragaceae Myriophyllum verticillatum LINNAEUS, 1753 Description: The seeds arc mm x mm. The shape is obovate but the diameter is rounded triangulate. The ventral side is slightly warty. Discussion: It occurred mainly during the Late-Glacial period but it was found in the interglacial deposits too, in Europe.

9 Hippuridaceae Hippuris vulgaris LINNAEUS, 1753 Description: The elliptic fruit is 1.6 mm x 0.8 mm in size. On the ventral side the funiculus-line is seen. Discussion: It appeared together with the former species from the Pliocene. It occurs most often in the Pleistocene deposits chiefly among the temperate fades in Europe. Urn belli ferae Oenanthe aquatica (LINNAEUS) POIRET, 1797 (Figs 10-11) Description: 2-3 mm x mm. The shape of the mericarpium is drop like (Figs 10-11). Discussion: This species is a characteristically interglacial plant in Europe. Labiatae Stachys palustris LINNAEUS, 1753 (Figs 8-9) Description: The measure is mm x mm. The shape is rounded oval. The diameter is rounded triangulate (Figs 8-9). Discussion: It is another interglacial species, but occurred from the Pliocene in Europe. THE INTERGLACIAL FLORA Thirty-eight species from 22 genera of angiosperms have been identified. Only three fossils could not be determined on the species level (Table 1). This interglacial flora, including the Characeae and the gymnosperms seems to be very similar to the modern flora of the temperate zone. Some species have a longer history going back to Pliocene; these survived the glacial periods (Stratiotes aloides, Lemna trisulca, Butomus umbellalus etc.). There are no characteristic Tertiary elements in this interglacial layer. Temperature, humidity and acidity values show the ecological requirements of plants (Figs 21-23). PLANT COMMUNITIES AND THE PAST ENVIRONMENT From the seed-flora in GyŐrújfalu various plant communities were reconstructed (Table 2). These différent communities represent a diversity of habitats around the Danube in the catchment area. As we know the fluvial sand and gravel continuously change and move so these fossils can not form an autochthonous assemblage. This locality must have been an old and broad bed of a branch of the Danube. Considering the great quantity of clay lens and tree trunks I can infer frequent and heavy floods at that time (RAL- SKA-JASIEWICZOWA & STARREL 1988). The contents of the clay boulders were very similar so I can suppose that the examined macrofossils (in clay) originated from one

10 Table 1. The seed-flora is characterized by the relative frequency of taxa taxa frequency taxa frequency Alisma plantago-aquatica 3 Oenanthe aquatica 5 Alnus sp. 1 Picea abies 5 Butomus umbellatus 2 Pinus sylvestris 5 Carex aquatilis 1 Polygonum lapathifolium 1 Carex caespitosa I Potamogeton gramineus 3 Carex elata 5 Potamogeton perfoliatus 5 Carex elongata 3 Ranunculus aquatilis 2 Carex gracilis 1 Ranunculus fluitans 1 Carex nigra 1 Ranunculus lingua 5 Carex pseudocyperus 2 Ranunculus nemorosus 1 Carex riparia 2 Ranunculus trichophyllus 1 Carex rost rata 1 Sagittaria sagittijblia 1 Carex sp. 3 Schoenoplectus lacustris 1 Carpinus betulus 1 Schoenoplectus tabernaemontani 2 Chara sp. 2 Scirpus sp. 3 Hippuris vulgaris 1 Scirpus sylvaticus 2 Hydrocharis morsus-ranae 1 Sparganium emersum 2 Lemna trisulca 1 Stachys palustris 4 Myriophyllum verticilla turn 4 Stratiotes aloides 3 Najas tenuissima 1 Thalictrum fiavum 1 Nitellopsis obtusa 5 Typha cf. latifolia 1 time and one area. If these fossils were associated in time, it is possible that they were also associated in space as communities (BIRKS & BIRKS 1980). The reconstruction uses indicator species approach based on the assumption that the ecological requirements and tolerance of the taxa have not changed significantly in time. If groups of taxa occur in the same way together either in the past or in the present our statement seems to be affirmed (BIRKS & BIRKS 1980). The fossil material (vertebrates, molluscs and plants) from the washing residue of the clay boulders indicates the environment around the Danube. Among the molluscs there are mainly aquatic and wetland species. Several species must have lived in alluvial forest. There are only few xerotherm elements of the fauna. These statements correspond to the results of my investigation based on the plant communities. These species and communities show the past vegetation which existed along the catchment area of the Danube. The origin of the tree trunks and the cones are very doubtful. I suppose this fossil material is mainly driftwood and maybe younger than the angiosperms.

11 Figs = Macrofossil diagram based on the climatic requirements of taxa in Győrújfalu ( I = cool-wet, 2 = temperate, 3 = atlantic-temperate, 4 = atlantic-submediterranean); 22 = Macrofossil diagram based on the humidity requirements of taxa in Győrújfalu (1 = temperately dry habitats - 7 = aquatic habitats); 23 = Macrofossil diagram based on the acidity requirements of taxa in Győrújfalu (1 = indifferent - 5 = calcareous habitats); 24 = Macrofossil diagram based on the warming water requirement of the obligate aquatic plants (1 = indifferent, 2 = warming water)

12 Plant community (some ecological characteristics) OPEN WATER AQUATICS Eutrophic, warming water FLOATING-LEAVED MACROPHYTES Table 2. The plant communities in GyŐrújfalu Eutrophic, warming and clean water, not drying out Taxa Nitellopsis obtusa Chara sp. Nitella sp. Lcinna trisulca Stratiotes aloides Hydrocharis morsus-ranae Najas tenuissima SUBMERGED MACROPHYTES Potamogeton perfoliatus Potamogeton g ram incus Eutrophic, clean and warming water, maximum Myriophyllum verticillatum 1 m deep, rarely drying out Ranunculus aquatilis Ranunculus trichophyllus Ranunculus fluitans REED SWAMP COMMUNITIES Eutrophic, warming, maximum 30-^10 cm deep water occasionally, shorter period of drying out all rooting in the substratum below water SEDGE SWAMP COMMUNITIES maximum 50 cm deep water occasionally water cover and drying out WET SWAMPLAND all rooting in organic deposits waterlogged ALDER SWAMP FOREST stable water-body occasionally drying out rooting in organic deposits A Usina plantago-aquatica Typha cf. latifolia Sag itta ria sag itt if o lia Schoenoplectus lacustris Scirpus sylvaticus Sparganium einer sum Stachys palustris Ranunculus lingua Oenanthe aquatica Hippuris vulgaris Butomus umbellatus Schoenoplectus tabernaemontani Carex pseudocyperus Carex riparia Carex rostrata Carex gracilis Carex aquatilis Carex caespitosa Carex elata Thal ic I rum flav urn Polygonum lapathyfolium Ranunculus nemorosus Alnus sp. Carex elongata Scirpus sylvaticus Carex pseudocyperus (Pinus sylvestris) (Picea able s)

13 Table 2 (continued) A. MIXED DECIDUOUS FOREST Pinus sylvestris Picea abies Carpinus betulus B. DECIDUOUS FOREST Carpinus betulus high ground water, growing on alluvial soil C. CONIFEROUS FOREST Pinus sylvestris growing on higher grounds outside the backwater area Picea abies A B C D E F G F G F H A B C I E G J Figs = The ideal sketch of the biotic succession of the present vegetation around the backwater in Szigetköz (after ZÓLYOMI 1937, SIMON 1975). 26 = The reconstructed, ideal sketch of the biotic succession of the past vegetation around the backwater near GyŐrújfalu (A = aquatic communities, B = reed swamp. C = sedge swamp, D = willow swamp, E = alder swamp forest, F = oak-ash-elm hardwood forest, G = hornbeam-oak forest, H = loess steppe with oak forest, I = open swampland, J = spruce-pine forest) Annlxhist.-nat. Mus. natn. hung. HS, 1996

14 From these communities more or less the whole succession of aquatic (backwater) and flood plain vegetation could be reconstructed. I can compare the past vegetation with the modern one around the backwaters of the Mosoni-Duna branch (Figs 25-26). The obligate aquatic species (Characeae, Myriophyllum, Potamogeton etc.) and their communities indicate the starting point of the vegetation succession. These plants must have lived in the broad backwater of the Danube which was cut off the main overdeveloped, meandering river. This water must have been maximum 2 metres deep, rich in nutrients (eutrophic), slightly calcareous (FELFÖLDY 1981, 1990) and getting warm (Fig. 24). Nowadays the dominant plant community is the Potamion on the open water surface. The following reedswamp communities (Phragmition) show the first phase of the filling near the bank. These plants (Typha, Schoenoplectus, Scirpus, Stachys palustris, Oenanthe aquatica etc.) stood in shallow, still water occasionally drying out. In higher places on the accumulated organogenic, reed peat sedge, tall herbs (Carex spp.) swamp communities (Magnocaricion) grew. The water table was shallow and often drying out. These plants such as Carex elata formed tussocks. The plants of relatively lower water-requirement (Thalictrum, Polygonum) formed marsh or swampland community on the wet, open habitats of the flood plain. The first step of the whole organogenic filling was indicated by the swamp forest, alder forest community (Alnion). I found only one pieces of fossil alder. But several typical Carex elongata species were found indicating the alder community. This community stood on the accumulated peat originating from reed and sedge plants. Finally on the same altitude of the highest flood plain alluvial, deciduous, hornbeam forest or mixed deciduous (hornbeam-pine) forest might have grown. This hornbeam forest was very similar to the modern Que reo robori-carpinetum. This community plays an interesting, unique role in the vegetation of Szigetköz nowadays. The hornbeam-oak forest is between the tipical alluvial hardwood forest (oak-ash-elm) and the climax dry oak forest in wet, but higher habitats. Under the trees there are no elements of the hardwood forest. The characteristic understorey plants belong to the Fagion. Unfortunately I have not found fossils which characterize this forest community. On the higher grounds of the northern area (outside the backwater area) coniferous forest may have existed. Picea abies was very common element of West European interglacial floras. I suppose that the driftwoods, pine and spruce of the coniferous forest may have come from the temporary, later part of this Cromer interglacial (or younger glacial period of the Pleistocene). The water plant associations were very similar in each interglacial, so these edaphic communities are not used for the exact climatic interpretation. We can infer the characteristics of this interglacial climate only in an indirect way. Considering the climatic requirements of both animals and plants, it can be said that this interglacial climate was very similar to the present temperate one, but more humid (JÁNOSSY & KROLOPP 1994). Nevertheless one important question emerges. If the age of the fossil assemblage is Cromer interglacial, then why the tipical, indicator Tertiary elements can not be found in the fluvial deposit? Among the fauna there are extant species indicating the exact age of the assemblage. But we must not exclude the redeposition of the sediment at the top

15 level, i. e. between m depth. It is proved by the examination of the mollusc fauna (JÁNOSSY & KROLOPP 1994). Nevertheless the great percentage of the Lower-Pleistocene indicator elements of the fauna define the stratigraphical position and age of this assemblage. We examined both the plants and molluscs in same clay boulders. On the basis of our results we can be sure that they originated in one time. According to the literature (WEST 1964) the climate of the Cromerian interglacial was rather temperate than warm and the Tertiary elements did not appear in significant amounts in West Europe. Another possible answer to the question is that these fossils came from the temporary later part of the interglacial cycle when the characteristic species were mixed and lived together. It is confirmed by the existence of coniferous forest. SUMMARY The age of the unique, very rich fossiliferous fauna and flora - layed in the fluvial deposit between metres depth - can be assessed in the upper part of the Lower- Pleistocene (Günz-Mindel, Cromer interglacial). This statement is based on the stratigraphy of the vertabrates (JÁNOSSY 1979) and molluscs (KROLOPP 1983). This layer seems to be very homogeneous biostratigraphically but we can not exclude the redeposition of the sediment on the top level. From the rich fossiliferous macroflora in Győrújfalu various plant communities could be reconstructed. The aquatic, wetland and terrestrial plant communities are very similar to the modern vegetation. Almost the whole vegetation succession can be traced in the catchment area from the eutrophic, open water to the drier and higher flood plain. In the bottom of the backwater the sediment accumulated, and gradually filled the backwater bed. Plants colonized the shallow riparian area. Fen communities occupied the margin of the backwater. As fen peat accumulated the wet habitats became drier and were colonized by trees. The terrestrial, woodland communities, the spruce forest and mixed pine-spruces forest may be younger than the others and grew in later or latest part of the interglacial. After the examination of the great number of driftwoods I can say more about this problem. The aquatic (probably a slowly flowing part of the river, i. e. a backwater) and the shore communities are the following: obligate aquatics (reed-grass-type, submerged communities, floating-leaved communities), fen communities (reed- and sedge swamp communities, the alder swamp forest). On the higher flood plain alluvial hornbeam forest close the vegetation sequences. * * * Acknowledgements -1 wish to say thanks to Z. TÓTH for his photos of the macrofossils. This study was supported by the Hungarian Scientific Research Fund (OTKA 14893).

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