The Late Early Pleistocene Flora Of Oriolo, Faenza (Italy): Assembly Of The Modern Forest Biome Author Denk, Thomas Author Sami, Marco Author Teodoridis, Vasilis Author Martinetto, Edoardo text Fossil Imprint 2022 2022-08-26 78 1 217 262 http://dx.doi.org/10.37520/fi.2022.009 journal article 10.37520/fi.2022.009 2533-4069 7167867 Acer aemilianum SORDELLI , 1896 Text-fig. 13a, d–g 1896 Acer aemilianum SORDELLI , p. 156, pl. 30, fig. 8. 1988 Acer polymorphum SIEBOLD et ZUCC. pliocenica SAPORTA; Jorda et al., p. 54, pl. 1, figs 10–13. M a t e r i a l. Oriolo MSF 645, 645-1, 660, 660-1, 661, 661-1. D e s c r i p t i o n. Leaf, petiolate, petiole ca. 3 cm long, with widened proximal part, lamina up to 52 mm long, 71 mm wide, primary venation palmate, number of primary veins 7–9 (–11), number of lobes 7–9 (–11), lobe apex attenuate, secondary venation craspedodromous, margin finely serrate or double-serrate along the upper 2/3 or 4/5 of the free lobes. R e m a r k s. The leaf remains from Oriolo clearly belong to A . aemilianum described by Sordelli (1896) from strata referred to as “Pliocene” (but possibly Early Pleistocene) in the surroundings of Fidenza (Emilia-Romagna). Leaves belonging to Acer section Palmata ( Van Gelderen et al. 1994 , Grimm et al. 2006 , Renner et al. 2008 ; including close to 50 modern species) from Miocene and Pliocene strata of western Eurasia have been referred to as Acer vindobonensis (ETTINGSH.) BERGER, 1955 ( Ettingshausen 1851 , Berger 1955 ) and A . sanctae-crucis STUR, 1867 ( Stur 1867 , Knobloch 1998 ; Tab. 1 ). Acer vindobonensis was based on a leaf fragment from Late Miocene strata of Austria ( Ettingshausen 1851 ; as Sterculia vindobonensis ETTINGSH. ) and described as palmate leaf with five entire margined lobes. Acer sanctae-crucis , described from Middle Miocene strata of Slovakia , has 7-lobed leaves, the lobes being elongate triangular with finely serrate margin. Subsequent authors either treated A . sanctae-crucis as synonym of A . vindobonensis (e.g., Menzel 1906 , Zastawniak 1972 , KovarEder 1988, Kovar-Eder et al. 1996 , Walther and Zastawniak 2005 ) or as distinct species (e.g., Berger 1955 , Iljinskaya 1968, Knobloch 1998 ). In addition, two fossil-species of sect. Palmata originally described from East Asia were reported from Europe. Of these, A . protojaponicum TANAI et ONOE, 1959 , is distinct by its shallowly lobed leaves, whereas A . nordenskioeldi NATH., 1883 , reported by Berger (1955 , 1957 ), resembles A . vindobonensis ( Tab. 1 ). Further, Saporta (1873 , 1879 ; see also Andreanszky 1959 ) used the name of a modern East Asian species for Pliocene (Cantal, France ) maple leaves, A . polymorphum SIEBOLD et ZUCC., 1845 (synonym of A . palmatum THUNB., 1784 ), and added pliocenicum without indicating a taxonomic rank. Similarly, Menzel (1906) used the modern name A . polymorphum and added miocenicum . While it is not the aim of this paper to revise western Eurasian Acer remains of sect. Palmata , we note that most of the taxonomic disagreement between previous authors discussing possible differences or conspecifity between A . vindobonensis and A . sanctae-crucis may be due to the fact that all previous authors compared these fossil-taxa (with the exception of the distinct A . protojaponicum ) to a single modern species, A . palmatum ( A . polymorphum ). One exception is the work by Stur (1867) , who indicated similarities with various species of sect. Palmata . Table 1 summarizes leaf characteristics of previously described fossil members of sect. Palmata from western Eurasia and lists similarities to modern species. This is highly informative in the case of A . vindobonense , for which a subentire margin has been refuted (e.g., Walther and Zastawniak 2005 ), perhaps simply because such a margin is not found in the modern A . palmatum . However, there are other members of sect. Palmata that can be compared with the subentire to remotely serrate leaves of A . vindobonensis , such as Acer sinense ( Tab. 1 ), which produces leaves nearly identical to A . vindobonensis . Thus, considering a broader set of modern species as possible modern analogues of fossil-taxa, we suggest that a thorough revision of both western Eurasian and East Asian fossil-taxa of sect. Palmata is needed (T. Denk, in preparation). Text-fig. 13. a, d–g: Acer aemilianum . b, c: Acer palmatum and A . sieboldianum modern leaves (NMNS Cleared Leaf Database). a: Oriolo MSF 661, 7-lobed leaf. b: Specimen U 1049, lobe detail showing finely serrate leaf margin. c: Specimen T 0246, 9-lobed leaf with coarsely serrate leaf margin. d: Oriolo MSF 645-1, 9-lobed leaf with two small additional lobes. e: Oriolo MSF 645. f: Oriolo MSF 660, 9-lobed specimen. g: Oriolo MSF 660-1. White arrows indicate position along lamina lobes where marginal serration starts. Scale bars 10 mm (a–c, f, g), 50 mm (d, e). Table 1. Comparative morphology of fossil-taxa of Acer sect. Palmata . aBerger 1955, bBerger 1955, 1957, cGivulescu and Ghiurca 1969, dLeroy and Roiron 1996, eGirard et al. 2019, fTanai 1976, 1983, gRayushkina 1979. Notes: Saporta (1873 , 1879 ) assigned leaves from Pliocene strata of France (Cantal) to Acer polymorphum SIEBOLD et ZUCC., 1845 pliocenicum SAPORTA , 1873. These leaves are 7–9-lobed, have remotely dentate lobes, teeth distinct and simple; similar to A . sinense var. longilobum W.P. FANG, 1939 . Menzel (1906) assigned leaves from the Late Miocene of Germany to Acer polymorphum SIEBOLD et ZUCC., 1845 miocenicum MENZEL , 1906. These leaves are 5-lobed with two basal additional lobes and are remotely dentate; they would need to be re-examined for taxonomic assessment. Barrón and Diéguez (2001) described a leaf from Early Miocene deposits of Spain as A . vindobonensis . Although this leaf differs markedly from A . vindobonense by the rhombic shape of the lobes, it might belong to sect. Palmata .

Western Eurasia Records of Acer sect. Palmata
Taxon	Acer vindobonensis (ETTINGSH.) BERGER, 1955	A. sanctae-crucis STUR, 1867	A. nordenskioeldi NATH., 1883	A. aemilianum SORDELLI , 1896	A. protojaponicum TANAI et ONOE, 1959
Age	Middle Miocene to Pliocene	Middle Miocene, Pliocene	Late Miocene	Piacenzian to latest Early Pleistocene	Late Miocene, Early Pleistocene
Morphology:
No. of lobes	5 lobed	7 lobed	7 lobedb	9 lobed, 7–11 lobed	9 lobed
Margin	Entire; weakly serratea	Finely serrate	Subentire, remotely serrateb	Finely serrate upper 2/3 of lobe	Serrate
Lobation	Deeply disected	Deeply disected	Deeply disected	Deeply disected	Shallowly disected
Geography:	Austria, Poland, Romania, Czech Republic, Hungary	Slovakia, Germany,?Romania,?Ukraine	Austria, Italy	Italy, France	France, Romaniac,d,e
Remarks	Similar to Acer sinense PAX, 1897 [ A campbellii subsp. sinense (PAX)	Similar to Acer sect. Palmata , incl. A. palmatum THUNB. ex MURRAY, 1784	Similar to Acer sinense PAX, 1897 [ A. campbellii subsp. sinense (PAX)	Similar to Acer sect. Palmata , e.g. Acer sieboldianum MIQ., 1865 .	Similar to Acer japonicum THUNB. ex MURRAY, 1784 .
P.C.DE JONG, 1994].	subsp. amoenum (CARRIÈRE) H.HARA ,	P.C.DE JONG, 1994].	Among fossil-taxa, leaves with 9 or
1954, A. ceriferum REHDER, 1911 , but not A. sinense .	Revision needed: These records may belong to A. vindobonensis .	more lobes are otherwise only seen in A. polymorphum pliocenicum ( Saporta, 1873 , 1879 ).
Taxon
Remarks

Underlined character states and countries refer to original descriptions and from where the fossil-species were described. Text-fig. 14. a, b: Acer aff. campestre . a: Oriolo MSF 664. b: Oriolo MSF 666. c, d: Acer aff. monspessulanum . c: Oriolo MSF 641. d: Oriolo MSF 662. e: Acer aff. opulus subsp. obtusatum Oriolo MSF 669. f, g: Acer aff. cappadocicum subsp. lobelii . f: Oriolo MSF 675. g: Oriolo MSF 631. h, i: Cornus sp. Oriolo MSF 655, two views of a strongly folded leaf impression. Scale bars 50 mm (a, e–g), 10 mm (b–d, h, i). The specimens from Oriolo differ from previously described fossil-species of Acer section Palmata by the lobe margin, which is serrate along most of the lamina, and by the variable and high number of lobes. According to Tanai (1983) , lobe number is taxonomically informative in extant and fossil species of A . sect. Palmata . For example, in A . nordenskioeldi from East Asia , a great number of examined specimens consistently had 5–7 lobes. Among modern members of sect. Palmata , A . sieboldianum produces leaves that match A . aemilianum by its number of lobes and the serrate margin. During the Middle Miocene to Pliocene, representatives of sect. Palmata were rare elements of several floras in western Eurasia ( Menzel 1906 , Knobloch 1969 , Kovar-Eder 1988 ). Acer sanctae-crucis s. str. might have had its last occurrence in the Pliocene flora of Willershausen, and Acer protojaponicum in the Early Pleistocene of France (ca. 2 Ma; Bernasso; Leroy and Roiron 1996 , Girard et al. 2019 ; Tab. 1 ). The new record from Oriolo extends the fossil record of sect. Palmata in Europe into the Pleistocene, ca. 0.84 Ma, before it was extirpated from Europe and Asia Minor . A time-calibrated molecular phylogeny of maples suggested that the Asian members of the Palmata clade ( Grimm et al. 2006 ) diverged from the single North American member during the Middle Miocene ( Renner et al. 2008 ). The fossil record further provides evidence that the section was fairly diverse in western Eurasia before it was extirpated in the Pleistocene.