Palaeofloral and stratigraphic context of a new fossil forest from the Pliocene of NW Italy

In Pliocene sedimentary successions of northern and central Italy, fossil swamp forests are relatively common.Most of them pertain to the Piacenzian stage and show a dominance of the coniferGlyptostrobus europaeusasan arboreal element. A new fossil forest that recently cropped out at Fossano in the Piedmont region representsthefirst Zanclean assemblage of this type. Herein, we describe the context of the site and report the consistentstratigraphic and palaeofloral results so far obtained, also highlighting the need of more detailed future studies.Our results demonstrate that the fossil stumps exposed at Fossano pertain to two superposed forest beds, and theupper one is covered by a dense buried litter ofGlyptostrobus europaeusshoots. Therefore, this conifer species isreconstructed as a dominant arboreal plant also in this fossil forest. Other interesting palaeontological informa-tion about the Pliocene succession of this relatively neglected area is provided by underlying and overlayinglayers. Detailed macropalaeobotanical studies on leaves, fruits and seeds, provide good evidence for thepalaeoecological and biochronological characterization of the succession. The integrated plant records (pollenand plant macrofossils) studied in a short interval of the succession correspond with the macrofossil records ofthe rest of the succession and point to the reconstruction of a“subtropical humid forest”grown under a verywarm temperate climate regime, with a small range of temperatures and abundant and well-distributed rainfallthroughout the year.© 2017 Elsevier B.V. All rights reserved.Keywords:PalaeobotanyCarpologyLeavesPiedmontLate Cenozoic1. IntroductionIn northern and central Italy, the infilling of marine andfluvio-lacus-trine basins during the Pliocene created favorable environments for thegrowth of swamp communities and for their preservation at the fossilstate, thanks to a still consistent subsidence combined with sea andlake level changes. In several of these sites, such as Dunarobba(Ambrosetti et al., 1995; Martinetto, 1994a; Martinetto et al., 2014), LaCassa (Martinetto, 1994a), Le Matole in the Upper Valdarno Basin(Bertini et al., 2014; Ielpi, 2012), Nole Canavese (Martinetto, 1994a;Martinetto et al., 2007; Vassio et al., 2008), Villafranca d'Asti-RDB Quar-ry (Forno et al., 2015; Martinetto and Mai, 1996), the coniferGlyptostrobus europaeushas been detected as a dominant arboreal ele-ment. Also in the late Cenozoic swamp forests of other parts of Europe(Erdei et al., 2009; Kovar-Eder et al., 2001)Glyptostrobus europaeushas been recognized as a characteristic tree and some recent evidenceeven suggests its survival until the Holocene on the southern shores ofthe Black Sea (Biltekin et al., 2015).A new fossil forest was recently detected close to the small town ofFossano (Cuneo province), in the bed of the Stura di Demonte river(Fig. 1), a site where a thick Pliocene succession crops out (Sacco,1886a), showing a complete palaeoenvironmental trend from a shallowmarine to afluvial-alluvial environment. However, the palaeofloral con-text of this interesting succession had not been investigated so far. TheFossano Fossil Forest is particularly interesting for the stratigraphic con-text in which it crops out and for the occurrence of animal fossils (landsnails) in several layers, including the palaeosols supporting the fossilstumps.Sacco (1886b)reported a diverse assemblage of continentalmolluscs with several extinct species from the continental layers ofthis succession, and more recent studies pointed out a high degree ofendemism among them (Esu and Ciangherotti, 2004). Given that thecontinental molluscs studied in other successions of northern Italy, ei-ther older (Colombero et al., 2017)oryounger(Ciangherotti et al.,Review of Palaeobotany and Palynology 248 (2018) 15–33⁎Corresponding author.E-mail address:edoardo.martinetto@unito.it(E. Martinetto).https://doi.org/10.1016/j.revpalbo.2017.08.0050034-6667/© 2017 Elsevier B.V. All rights reserved.Contents lists available atScienceDirectReview of Palaeobotany and Palynologyjournal homepage:www.elsevier.com/locate/revpalbo