Brachycarcharias lerichei (Casier, 1946)

Kovalchuk, Oleksandr, Kriwet, Jürgen, Shimada, Kenshu, Ryabokon, Tamara, Barkaszi, Zoltán, Dubikovska, Anastasiia, Anfimova, Galina & Davydenko, Svitozar, 2023, Middle Eocene cartilaginous fishes (Vertebrata: Chondrichthyes) of the Dnieper-Donets Basin, northern Ukraine, Palaeontologia Electronica (a 32) 26 (2), pp. 1-37 : 12

Brachycarcharias lerichei (Casier, 1946)

Figure 4N–O

1861 Otodus macrotus Ag. (partim); Rogovich, p. 43, pl. V, fig. 23.

1946 Lamna lerichei n. sp.; Casier, p. 80, pl. 2, fig. 7a-b.

1988 Lamna lerichei Casier ; Nolf, pl. 30, figs. 2- 11.

1990 Lamna lerichei Casier ; Kemp et al., p. 9, pl. 3, figs. 9, 10.

2005 Brachycarcharias lerichei (Casier, 1946) ; Cappetta and Nolf, p. 241-242, pl. 2.

2012 Brachycarcharias lerichei (Casier, 1946) ; Diedrich, p. 19, fig. 14.1-14.6.

2013 Brachycarcharias lerichei (Casier, 1946) ; Clayton et al., fig. 2L.

2016 Brachycarcharias lerichei (Casier, 1946) ; Cappetta and Case, pl. 3, figs. 8-22.

2018 Brachycarcharias lerichei (Casier, 1946) ; Marramà et al., p. 291, fig. 4.

2019 Brachycarcharias lerichei (Casier, 1946) ; Ebersole et al., p. 39-41, fig. 13.

2022 Brachycrcharias lerichei ; Perez, p. 635, fig. 4A-B.

Material. One lower lateral tooth, NMNHU-G 391/

52, Vyshhorod.

Description. The lateral tooth has a triangular crown; its height reaches 14.0 mm, and its width is

14.3 mm. The main cusp is slightly inclined distally and has an accentuated apex. There are two pairs of triangular lateral cusplets, the first of which is considerably larger than the second one. The crown surface is smooth and devoid of ornamentation. The root is holaulacorhize with a V-shaped interlobe area. There is a shallow nutritive groove on the lingual root protuberance.

Remarks. The specimen described here is identical in morphology and size to teeth of Brachycarcharias lerichei (Casier, 1946) . It differs from the respective teeth of other species of this genus in their smaller overall size, narrower main cusp, and smaller lateral cusplets (see Ebersole et al., 2019, for more details). In addition, the specimen considered differs from those of the coeval Brachycarcharias atlasi (Arambourg, 1952) in the absence of faint striations at the lingual crown base. The lateral teeth of Hypotodus have smaller and less divergent cusplets compared to B. lerichei . The latter species is characterised by less hooked lateral teeth with larger lateral cusplets than those in Jaekelotodus (Ebersole et al., 2019) . In addition, the surface of the lateral teeth of Striatolamia macrota is ornamented, their lateral cusplets are blunt, and the root lobes are slightly wider. Brachycarcharias lerichei was distributed across the Northern Hemisphere during the early Paleogene (Marramà et al., 2018; Ebersole et al., 2019).

Figures

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 NMNHU- G 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.