Striatolamia cederstroemi Siverson, 1995

Adolfssen, Jan S. & Ward, David J., 2015, Neoselachians from the Danian (early Paleocene) of Denmark, Acta Palaeontologica Polonica 60 (2), pp. 313-338 : 327-328

Striatolamia cederstroemi Siverson, 1995

Fig. 6D–H .

1995 Striatolamia cederstroemi sp. nov.; Siverson 1995: 9, fig. 3K–P. See Siverson (1995) for further synonomy.

Material.— Five specimens ( OESM-10046-5 , OESM-10046- 6 , OESM-10046-11 , OESM-10046-12 , OESM-10046-18 ) and several others in a private collection (Alice Rasmussen, Faxe), all from the Br2 of Faxe .

Description.—Teeth with an elongated main cusp, strongly sigmoid in anteriors, less so in laterals. Cusplets are only present in anterior teeth where they are small and blunt, often with an entirely flattened apex. In lateral teeth, the cusplets are lacking and instead the shoulders are mesio-distally very well developed. Both faces of the crown are in general smooth, but loose smaller cusps found at the same locality with similar affinity carry lingual folds. The root is low and bilobed and has elongated lobes. The lingual face of the root has a prominent median protuberance with a nutrition groove.

Remarks.— S. cederstroemi differs from S. striata by being smooth or lightly lingually striated and having more narrow root extremities, whereas the latter has strong lingual folds and wider root lobes.

Siverson (1995) tentatively assigned Striatolamia to Mitsukurinidae , a position that has been followed by Cappetta and Nolf (2005) and Cappetta (2012). He based his opinion on the similarity of the teeth of Striatolamia to those of a generalised Anomotodon . However, Siverson (1995: 9) also stated “I am not completely convinced that the latter genus [ Anomotodon ] is a true mitsukurinid taxon, hence the assignment of Striatolamia to Mitsukurinidae in a broad sense”. Cunningham (2000), using an artificial tooth set, conducted a detailed, position-by-position comparison of the teeth of Striatolamia macrota (Agassiz, 1843) with those of Recent Carcharias taurus . His data demonstrated a very close similarity between the two, closer than between Recent Carcharias and Odontaspis . On the basis of its dental similarity to C. taurus , we prefer to group Striatolamia with Carcharias in the Carchariidae .

Stratigraphic and geographic range.— Striatolamia cederstroemi is only known from the Danian (early Paleocene) of Denmark and Sweden.

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Figures

Fig. 6. Lamniformes from the Danian of Stevns Kridtbrud, Karlstrup kalkgrav, and Faxe kalkbrud. A–C. Carcharias aff. gracilis (Davis, 1890). A. MGUH 29852 (Ce) anterior tooth in labial view. B. MGUH 29853 (Ce) anterior tooth in labial (B) and lingual (B) views. C. MGUH 29854 (Ce) anterior tooth in 1 2 labial (C) and lingual (C) views. D–H. Striatolamia cederstroemi Siverson, 1995. D. OESM-10046-5 (Br2) anterior tooth in labial (D) and lingual (D) 1 2 1 2 views. E. OESM-10046-6 (Br2) anterior tooth in labial (E) and lingual (E) views. F. OESM-10046-18 (Br2) anterior tooth in lateral (F), labial (F), and 1 2 1 2 lingual (F) views. G. OESM-10046-12 (Br2) lateral tooth in labial (G) and lingual (G) views. H. OESM-10046-11 (Br2) lateral tooth in labial (H) and 3 1 2 1 lingual (H) views. I. Odontaspis speyeri Dartevelle and Casier, 1943, OESM-10046-8 (Br2) anterior tooth in labial (I) and lingual (I) views. J–L. Palae2 1 2 ohypotodus aff. bronni (Agassiz, 1843). J. MGUH 29855 (Ce) anterior tooth in labial (J), basal (J), and lateral (J) views. K. MGUH 298457 (Br1) lower 1 2 3 anterior tooth in labial (K ), lingual (K ) views. L. MGUH 29856 (Ce) posterior tooth in labial (L ) and lingual (L ) views.