Heptranchias howelli ( Reed, 1946 )

Szabó, Márton & Kocsis, László, 2016, A preliminary report on the Early Oligocene (Rupelian, Kiscellian) selachians from the Kiscell Formation (Buda Mts, Hungary), with the re-discovery of Wilhelm Weiler’s shark teeth, Fragmenta Palaeontologica Hungarica 33, pp. 31-64 : 40

Heptranchias howelli ( Reed, 1946)

( Figs 18–23 )

1938 Fam. et gen. indet. (Inc. sed.) – WEILER, pl. 1, fig. 15.

1946 Notidanion howelli n. sp. – REED, pp. 1–3, figs 1–4.

1995 Heptranchias sp. – SIVERSON, pp. 4–5, figs 2A-C.

2009 Heptranchias howelli ( Reed, 1946) – BIEŃKOWSKA-WASILUK & RADWAŃSKI, pp. 238–239, pl. 1, figs 1–5.

2012 Heptranchias howelli ( Reed, 1946) – CAPPETTA, p. 99, fig. 86.

2014 Heptranchias howelli Reed, 1946 – CARLSEN & CUNY, p. 64, figs 16A-B.

2014 Heptranchias sp. – REINECKE et al., pp. 10–11, pl. 5, figs 1–5.

2015 Heptranchias howelli ( Reed, 1946) – ADOLFFSEN & WARD, pp. 7–8, figs 2L-M.

Referred material: 3 teeth (V.61.814., VER 2016.3452., VER 2016.3453.).

Remarks: In general, teeth of Heptranchias have typical hexanchid morphology (see above at N. primigenius and H. agassizi ). The lower teeth are wider than the upper teeth, while cusplets of the upper teeth are distally bent, and more elongated. The upper anteriors bear no cusplets, but an elongated main cusp, strongly sigmoid in shape from labiolingual view ( Figs 18–19 ). The upper lateral teeth have a distally bent (or sometimes weakly sigmoid) main cusp, which outgrows the distally also bent distal and mesial cusplets ( Figs 20–21 ). The principal cusp of the lower lateral teeth is longer than the distal cusplets, which are nearly in the same size – except the most distal 1–2 cusplets ( Figs 22–23 ; see CAPPETTA 2012, fig. 86E-F; TRIKOLIDI 2014, fig. 15). The root is mesiodistally wide, and labiolingually flattened on every file. Among all tooth positions, lower laterals are the taxonomically most significant.

One upper anterior tooth (morphologically identical with the figured specimen of CAPPETTA 2012, fig. 86A) is known in the collection of the HNHM ( Figs 18–19 ). The upper lateral figured by WEILER (1938, pl. 1, fig. 15; also Fig. 21 of this work) is closely identical with the one figured by CAPPETTA (2012, fig. 86C, D). This tooth (VER 2016.3453.) was found among the non-catalogued HNHM material, with an old, handwritten label under it (“ Inc. sed. Taf. I. Fig. 15 ”).

Heptranchias is a neritic (relatively deep water) form known from the Late Cretaceous (Campanian), exists up to nowadays with one recent species, Heptranchias perlo (Bonnaterre, 1788) , also known as sharpnose sevengill shark. Fossils of the genus are all isolated tooth remains, which are not common in any geological deposits ( CAPPETTA 2012). The genus has also been reported by REINECKE et al. (2014) from the Chattian of the Thalberg Beds (Bavaria, Germany), which material seems to show affinity with the species H. howelli , however, only upper anteriors and upper laterals have been published there. Lower laterals of H. howelli have been reported from the Lower Oligocene Menilite Formation of the Polish Outer Carpathians ( BIEŃKOWSKA-WASILUK & RADWAŃSKI 2009), from the Early Paleocene (Danian) of Denmark ( ADOLFFSEN & WARD 2015) and from the Middle Eocene (Late Ypresian to Middle Lutetian) Lillebaelt Clay of Denmark ( CARLSEN & CUNY 2014).

Figures

Figs 18–23. Heptranchias howelli (Reed, 1946). – 18–19. Upper anterior tooth (VER 2016.3452.). – 18. Lingual view. – 19. Labial view. – 20. Upper lateral tooth (VER 2016.3453.), lingual view. – 21. Specimen VER 2016.3453. as figured by WEILER (1938). – 22. Imprint of a lower lateral tooth (V.61.814.); tooth contour of the specimen has been reconstructed based on the specimen on Fig. 23. – 23. Lower lateral tooth, lingual view (specimen in private collection of Peter Picard). – Figs 24–27. Araloselachus cuspidatus (Agassiz, 1843). – 24. Anterior tooth (V.61.671.), labial view. – 25–27. Distal tooth (VER 2016.3447.). – 25. Lingual view. – 26. Apical view. – 27. Labial view. Scale bars: 18–20, 22–23: 5 mm; 24–27: 10 mm