Promephitis maeotica ALEXEJEW, 1915

Tesakov, Alexey S., Titov, Vadim V., Simakova, Alexandra N., Frolov, Pavel D., Syromyatnikova, Elena V., Kurshakov, Sergey V., Volkova, Natalia V., Trikhunkov, Yaroslav I., Sotnikova, Marina V., Kruskop, Sergey V., Zelenkov, Nikita V., Tesakova, Ekaterina M. & Palatov, Dmitry M., 2017, Late Miocene (Early Turolian) Vertebrate Faunas And Associated Biotic Record Of The Northern Caucasus: Geology, Taxonomy, Palaeoenvironment, Biochronology, Fossil Imprint 73 (3 - 4), pp. 383-444 : 414-415

Promephitis maeotica ALEXEJEW, 1915

Text-figs 16a–c , 17

M a t e r i a l. p 4 dex (GIN-1144-302): Gaverdovsky.

D e s c r i p t i o n. The fourth lower premolar corresponds in size (L × W = 3.8 × 2.5) and shape to p4 of the fossil skunk Promephitis from the European Turolian ( Text-fig. 16a–c ). As in other Promephitis , the high crowned p4 has an almost triangular occlusal outline with significant distal broadening of the crown. It also corresponds with Turolian skunks in the presence of two roots and a single tall main cusp with a well developed posterior cingular cusp(id) as well as in the presence of a weak anterior and more distinct posterior cingulae. In addition, the main cuspid of p4 from Gaverdovsky bears mesial and distal ridges and a prominent lingual crest. A well developed lingual cingulum which forms a bulge at the junction of the lingual crest with the base of the crown is also present.

C o m p a r i s o n a n d d i s c u s s i o n. Among European taxa, p4 from Gaverdovsky is larger than in Promephitis majori and lies within the variability range of the Turolian species P. maeotica and P. lartetii (Textfig. 17). A variety of views on the systematics of these two species have been recently published. Therefore it is worth discussing their taxonomic position before any morphological comparison is made.

Fossil skunks Promephitis were common elements of the Turolian carnivoran assemblages. They were widespread in Late Miocene of Eurasia and survived till the Pliocene in Asia. The genus includes about ten species with some of them being poorly defined thus leading to an ongoing discussion on the taxonomic composition of the genus ( Wang and Qiu 2004, Koufos 2006, Geraads and Spassov 2016).

Werdelin (1996) recognised four species among European Promephitis : P. pristinidens , P. maeotica , P. lartetii , and P. brevirostris . According Ginsburg’s (1999) concept, Europe was inhabited by only three species, the Vallesian P. gaudryi and P. pristinidens , and Turolian P. lartetii , while P. majori and P. maeotica were considered as synonyms of the latter species.

In a recent revision Geraads and Spassov (2016) questioned the affiliation of the Vallesian species P. gaudryi and P. pristinidens to Promephitis , listed two other taxa P. brevirostris and P. malustenensis as problematic and found that Turkish species P. hootoni is a synonym of P. lartetii . Finally they recognized only three species in the Turolian of Western Eurasia: the largest being P. maeotica from Novoelizavetovka ( Ukraine) (MN 12), the slightly smaller P. lartetii (= P. hootoni ) from Pikermi, Perivolaki ( Greece), Küçükyozgat, Akkaşdaği ( Turkey), Hadjidimovo, and Kalimantsi ( Bulgaria) (MN 11–12), and the notably smaller P. majori from Samos ( Greece) and Hadjidimovo ( Bulgaria) (MN 11–12).

Thanks to the new finds from Greece and Bulgaria, the cranial-based distinctions between P. lartetii and P. maeotica finally excluded their synonymy ( Koufos 2006, Geraads and Spassov 2016). The important derived feature of P. maeotica from different stratigraphical levels of Turolian is the long m1. The length range of p 4 in the three discussed species is quite narrow (3.0–4.0 mm, n = 11; Text-fig. 16 ) while the length difference between m1 of P. maeotica (9.5–10.8 mm, n = 6) and P. majori and P. lartetii (7.9–9.3 mm, n = 11) is considerable and the values do not overlap.

As noted above the p4 of Turolian skunks do not significantly differ in linear dimensions, but their L/W ratio is not a stable characteristic ( Text-fig. 16 ). The skunk from Gaverdovsky has a relatively long and narrow p4 that is more similar to P. majori than to other discussed taxa. Wang and Qiu (2004) speculated that the broadening of p4 is a derived condition shared by advanced species of Promephitis and concluded that P. majori is the most plesiomorphic taxon among the discussed forms. From this point of view P. maeotica from Novoelizavetovka and Grebeniki as well as all specimens assigned to P. lartetii are derived relative to the Gaverdovsky skunk. Text-fig. 17 however shows the wide variability range of the character which therefore questions its reliability as a taxonomic marker.

Unfortunately, the morphology of p 4 in Promephitis is insufficiently known. Nevertheless, none of the students described the presence of the strong lingual cingulum plus crest and bulge on the internal wall of p 4 in P. majori and P. lartetii , which are present on the Gaverdovsky tooth. On the other hand, Krokos (1939) noted the presence of a strong lingual cingulum in p3 and p4 of the early Turolian skunk from Grebeniki. Our examination of the material from the middle Turolian site of Novoelizavetovka showed the presence of cingula in lower premolars, though somewhat less expressed in premolars of the specimen PIN-355. It is therefore possible to assign the skunk from Gaverdovsky to P. maeotica . The specific morphological features of the described form, such as the complex structure of the lingual wall and lack of the anterior cingular cusp characterise a somewhat more basal morphotype of p4 that most likely fits the early Turolian age of the fauna.

Figures

Text-fig. 16. Carnivorans from Gaverdovsky and Volchaya Balka, Late Miocene, North Caucasus. a–c – Promephitis maeotica, p4, dex, GIN-1144-302, a – labial, b – lingual, c – occlusal view; d–e –?Procyonidae gen., occlusal view; d – dP3, sin, GIN-1143-401, e – dP4, sin, GIN-1144-301.

Text-fig. 17. Scatter diagram of length and width of Promephitis species from Late Miocene faunas of southern Europe and western Asia. a – Promephitis maeotica, p4, dex, Gaverdovsky, GIN-1144-301: labial (left) and lingual (right) views. b – P. maeotica, p4, sin, reversed, Novoelizavetovka, PIN-355: labial (left) and lingual (right) views. Scale 1 mm.

Text-fig. 4. Palynological diagrams of Late Miocene deposits, North Caucasus. a. Tuapse highway bridge. b. Gaverdovsky. c. Volchaya Balka.