Middle Eocene cartilaginous fishes (Vertebrata: Chondrichthyes) of the Dnieper-Donets Basin, northern Ukraine Author Kovalchuk, Oleksandr Author Kriwet, Jürgen Author Shimada, Kenshu Author Ryabokon, Tamara Author Barkaszi, Zoltán Author Dubikovska, Anastasiia Author Anfimova, Galina Author Davydenko, Svitozar text Palaeontologia Electronica 2023 a 32 26 2 1 37 http://dx.doi.org/10.26879/1283 journal article 10.26879/1283 1094-8074 12654814 Notorynchus kempi Ward, 1979 Figure 4D–E FIGURE 4. Hexanchiform, heterodontiform and lamniform shark teeth from the middle Eocene deposits of Vyshhorod: A-C – Hexanchus agassizi Cappetta, 1976 , upper anterolateral tooth NMNHU-G 391/21/2 ( A ), lower lateral teeth NMNHU-G 391/21/3 ( B ) and NMNHU-G 391/21/4 ( C ); D-E – Notorynchus kempi Ward, 1979 , upper anterolateral tooth NMNHU-G 391/20 ( D ), lower lateral tooth NMNHU-G 391/21/1 ( E ); F – Heterodontus sp. , lateral tooth NMNHUG 391/6; G-M – Striatolamia macrota (Agassiz, 1843) , upper lateral teeth NMNHU-G 391/105 ( G-H ), NMNHU-G 391/ 54 ( I-J ), NMNHU-G 391/55 ( K-L ), upper posterior tooth NMNHU-G 391/92 ( M ); N-O – Brachycarcharias lerichei (Casier, 1946) , lower lateral tooth NMNHU-G 391/52. Lingual view in A , H , J -K , M , and O , labial view in B-G, I, L, and N . 1861 Notidanus serratissimus Ag. ; Rogovich, p. 29, pl. III, figs. 23, 24. 1912 Notidanus primigenius Ag. ; Savtchenko, p. 168-170, pl. XIII, figs. 11, 12. 1979 Notorynchus kempi sp. nov. ; Ward, p. 121- 122, pl. 3, figs. 4-7. 1999 Notorhynchus kempi ; Zhelezko and Kozlov, pl. 32, figs. 4a-9b, pl. 34, figs. 1-6. 2006 Notorhynchus kempi Ward, 1979 ; Udovichenko, p. 204, pl. I, fig. 5. Material. One upper left anterolateral tooth, NMNHU-G 391/20; one lower left lateral tooth, NMNHU-G 391/21/1, Vyshhorod. Description. The upper anterolateral tooth ( Figure 4D ) is quite large, 15.6 mm wide and 18.0 mm high, with an erect, convex crown inclined distally and possessing a complete cutting edge. The root is wide, compressed labiolingually, and wedgeshaped in anterior view (the lingual surface is steeply inclined towards the root base); its mesial and apical edges form a right angle. There is a single weakly serrated mesial cusplet and two separated distal cusplets, the first of which is almost two times shorter than the main cusp. The lower lateral tooth ( Figure 4E ) is 24.8 mm wide and 12.3 mm high. Its crown is labiolingually compressed and mesiodistally extended with an acrocone followed by six gradually decreasing lateral cusplets angled posteriorly. There are eight or nine small denticles increasing in size apically on the mesial edge of the main cusp. Remarks. The specimens described were assigned to the genus Notorynchus based on the presence of denticles on the mesial edge of the main cusp of lower lateral teeth (Applegate, 1965; Kocsis, 2007) and a characteristic shape of the upper anterolateral tooth (Cappetta, 2012). These teeth resemble those in Notorynchus kempi Ward, 1979 , in overall morphology and size. The teeth of N. serratissimus (Agassiz, 1843) are considerably smaller, have relatively coarser mesial cusplets as well as less numerous, larger, and less curved distal cusplets (Ward, 1979). As compared to N. kempi Ward, 1979 , N. primigenius is characterised by larger tooth size, coarser mesial cusplets, relatively larger, more pointed, and upright main cusp and distal cusplets (Ward, 1979). The specimens considered differ from N. cepedianus (Péron, 1807) in having a smaller overall tooth size and more erect cusplets. Notorynchus kempi ranged from the middle to late Eocene, being restricted to Zones NP 15–17 (Ward, 1979; Udovichenko, 2006). This species originally was described from the Bartonian of England (Ward, 1979), and later its remains were also found in Kazakhstan (Zhelezko and Kozlov, 1999) and Ukraine (Udovichenko, 2006).