Journal of Paleontology, 91(6), 2017, p. 1258–1271 Copyright © 2017, The Paleontological Society 0022-3360/17/0088-0906 doi: 10.1017/jpa.2017.73


The Kvabebi Canidae record revisited (late Pliocene, Sighnaghi, eastern Georgia)


Lorenzo Rook,1 Saverio Bartolini Lucenti,1,2 Maia Bukhsianidze,3 and David Lordkipanidze3


1Dipartimento di Scienze della Terra, Università di Firenze, Via G. La Pira 4, 50121 Firenze, Italy ⟨lorenzo.rook@unifi.it⟩ 2Dottorato di Ricerca in Scienze della Terra, Università di Pisa, Via S. Maria 53, 56126 Pisa, Italy ⟨saverio.bartolini@dst.unipi.it⟩ 3Georgian National Museum, 3, Rustaveli ave., Tbilisi-0105, Georgia ⟨maiabukh@gmail.com⟩; ⟨dlordkipanidze@museum.ge⟩


Abstract.—Unlike the Asian and North American Pliocene record, fossil occurrences of Canidae in Europe (and Africa) are uncommon and fragmentary. The revision of canid material from the late Pliocene site of Kvabebi (eastern Georgia) revealed the contemporaneous occurrence of three different taxa: (1) Nyctereutes megamastoides


(a derived species of the Eurasian Pliocene raccoon dog-like canids); (2) Vulpes cf. V. alopecoides (representing the first occurrence of a member of the vulpine taxon V. alopecoides, a species that was the most widespread fox in the early Pleistocene in western Europe); and (3) Eucyon sp. The latter occurrence at Kvabebi completes our knowledge of the late Pliocene evolutionary history of the latest representatives of the genus in Western Europe and Central Asia. Our revision of Kvabebi canids registers a previously undocumented case of established niche partition- ing among early Pliocene sympatric Canidae.


Introduction


The European record of Pliocene canids is relatively scanty and consists mainly of a few specimens in isolated occurrences. The most common taxon recovered from early Pliocene sites is the genus Nyctereutes Temminck, 1838, whereas the genus Eucyon Tedford and Qiu, 1996 is more elusive during this period. The genus Vulpes Frisch, 1775, which has been present in North America and Africa since the late Miocene, is documented in Eurasia only from the early Pliocene (Wang and Tedford, 2008). Vekua (1972) described the fossil assemblage of Kvabebi,


a late Pliocene site (MN16a in the European Land Mammal biochronology). Mein (1975a, b) and Agustí et al. (2009) reported the co-occurrence of Nyctereutes megamastoides (Pomel, 1842) and Canis sp. in Eastern Georgia. Agustí et al. (2009) provided a general revision of the Kvabebi fauna and its chronological position. The authors, by providing a magneto- stratigraphic calibration of the Kvabebi succession to the late Pliocene (chron 2An.1r), reviewed the faunal list ascribing the canid record to the genera Nyctereutes and Eucyon. In the framework of a joint collaborative project between the University of Florence and the Georgian National Museum (GNM), the Kvabebi Canidae sample has been revised to examine its role in determining the evolutionary history of the Plio-Pleistocene canid guild of the OldWorld. This revision of all the available material from Kvabebi housed in the GNM paleontological collections allowed us to identify the co-occurrence of three different canids in the same fossil assemblage: Nyctereutes, Eucyon,and Vulpes. This association is remarkable for its diversity and because it includes the first occurrence of a Vulpes alopecoides-like fox in the European fossil record.


Geological and chronological context of the Kvabebi site.— Kvabebi is located south of Magaro village, in the area of the Sighnaghi region of eastern Georgia that surrounds Kvabebi Mountain, on the southern edge of the Iori Plateau. The Kvabebi section sits in the sedimentary infill of the Kura Basin. The latter, since the late Neogene, has been bordered by the Greater Caucasus to northeast and by the Lesser Caucasus and the Talysh ranges to the southwest (Agustí et al., 2009, fig. 1), and it formed as a northward inland ingression of the Caspian (Popov et al., 2006). The Kvabebi section, which is in the middle part of theAkchagylian stage of the Caspian Paratethys (Vekua, 1972), is ~170m thick and displays a general regressive trend. The lower 110m of the section is built up of a succession of brownish


and bluish laminated mudstones. The brownish sediments are of fluvio-lacustrine origin, whereas the bluish color testifies to transgressive (marine) events characterized by a Pliocene (Akchagylian)mollusk fauna (Djikia, 1968). The upper part of the section (from 110m to the top) is formed by a succession of alluvial reddish-brown sediments with no marine fauna. The sec- tion is characterised by the occurrence of several sandstone layers, including the one that yielded the Kvabebi fossil vertebrate assemblage (at meter 40), which is the result of accumulation due to tractive processes in a fluvial-influenced environment (Agustí et al., 2009). Recent re-prospecting and re-excavating conducted at


Kvabebi allowed a re-evaluation of the geochronological setting of the section and a revision of the vertebrate fauna assemblage (Agustí et al., 2009). A magnetostratigraphic study allowed placement of the fossiliferous level within the polarity reversals chron 2An.1r, with an age of ca. 3.07 Ma for the Kvabebi site (Agustí et al., 2009). The updated revised list of the Kvabebi


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