Macrorhizodus praecursor (Leriche, 1905)

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 : 16

publication ID

https://doi.org/ 10.26879/1283

persistent identifier

https://treatment.plazi.org/id/A1525343-662B-FF9C-FF6A-B7DDFBBFF9C3

treatment provided by

Felipe

scientific name

Macrorhizodus praecursor (Leriche, 1905)
status

 

Macrorhizodus praecursor (Leriche, 1905)

Figure 6A–H View FIGURE 6

1861 Lamna lata Rog. ; Rogovich, p. 49, pl. VII, figs. 1-2a.

1861 Oxyrhina Desorii [sic] Ag.; Rogovich, p. 54, pl. VIII, figs. 1-3.

1905 Oxyrhina desori praecursor ; Leriche,

p. 128.

1928 Oxyrhina desori Sismonda ; Menner,

p. 304, pl. X, figs. 28-31.

1928 Oxyrhina desori mut. praecursor Leriche ; Menner, p. 305.

1942 Oxyrhina praecursor americana ; Leriche, p. 45, pl. 3, figs. 6-13.

2002 Cosmopolitodus praecursor ; Mustafa and Zalmout, p. 82, pl. 1, figs. 7-11.

2005 Cosmopolitodus praecursor (Leriche, 1905) ; Mustafa et al., p. 408-409, figs. 14- 20.

2006 Isurus praecursor (Leriche) ; Udovichenko, p. 202, pl. I, fig. 16.

2011 Macrorhizodus praecursor (Leriche, 1905) ; Underwood et al., p. 54, fig. 4C, D.

2012 Macrorhizodus praecursor (Leriche, 1905) ; Cappetta, p. 221-222, fig. 207.

2012 Isurus praecursor (Leriche, 1905) ; Diedrich, p. 15, fig. 11.1-11.10.

2012 Macrorhizodus praecursor (Leriche, 1905) ; Zalmout et al., p. 76, fig. 4A-V.

2013 Macrorhizodus praecursor (Leriche, 1905) ; Otero et al., fig. 3.28-3.34.

2013 Macrorhizodus praecursor (Leriche, 1905) ; Malyshkina et al., pl. 13, fig. 7.

2017 Macrorhizodus praecursor (Leriche, 1905) ; Zalat et al., p. 207; pl. 1, fig. 5.

2019 Macrorhizodus praecursor (Leriche, 1905) ; Ebersole et al., p. 56-58, fig. 20.

2019 Macrorhizodus praecursor (Leriche, 1905) ; Trif et al., p. 8, fig. 5.1-5.4.

2021 Macrorhizodus praecursor (Leriche, 1905) ; Adnet et al., p. 31, fig. 4.1-4.4.

2021 Macrorhizodus praecursor (Leriche, 1905) ; Zouhri et al., p. 125, fig. 2H-K.

2022 Macrorhizodus praecursor (Leriche, 1905) ;

Perez, p. 635, fig. 4L, M.

Material. One anterior tooth, NMNHU-G 391/101; one anterolateral tooth, NMNHU-G 391/103, Vyshhorod; one additional anterior tooth, NMNHU-G 391/68, and one additional anterolateral tooth, NMNHU-G 391/69, also from Vyshhorod, tentatively identified to this taxon.

Description. NMNHU-G 391/101 ( Figure 6A–B View FIGURE 6 ) is quite large, although the crown is broken at the tip; therefore, it is not possible to measure its apicobasal height. The main cusp is stout, has a lingual inclination in profile, and is not accompanied by any cusplets. Both the labial and lingual faces of the crown are smooth and convex. The cutting edges extend from the apex to the crown base. The robust root ends with lanceolate lobes, one of which is partly broken.

NMNHU-G 391/68 ( Figure 6C–D View FIGURE 6 ) represents a crown broken at the base near its junction with the root. The crown is triangular and reaches 19.4 mm mesiodistally. Its labial face is almost flat, whereas the lingual face is convex. The cutting edges extend to the crown base.

NMNHU-G 391/103 ( Figure 6E–F View FIGURE 6 ) measures 23.8 mm apicobasally and 17.6 mm mesiodistally. The triangular cusp is shorter than that in the anterior tooth. The root lobes with slightly pointed tips are unequal in length. There is a weak lingual protuberance on the root.

NMNHU-G 391/69 ( Figure 6G–H View FIGURE 6 ) measures 22.8 mm apicobasally and ca. 20.5 mm mesiodistally. It is preserved better, albeit its root is broken. The cusp is asymmetrical and lateral cusplets are absent. Both the mesial and distal cutting edges are convex.

Remarks. The specimens described are morphologically similar to those in Macrorhizodus praecursor and fit well into the diagnosis of this species. Macrorhizodus praecursor had a worldwide distribution during the middle and late Eocene (Cappetta, 2012; Adnet et al., 2021). However, the taxonomic identification of NMNHU-G 391/68 and NMNHU-G 391/69 is tentative because of their poor state of preservation, particularly due to the absence of roots.

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