Scyliorhinus Blainville, 1816
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https://doi.org/ 10.4202/app.2012.0123 |
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persistent identifier |
https://treatment.plazi.org/id/C45E8796-696C-1961-FC91-3FEDFBFBB6B2 |
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treatment provided by |
Felipe |
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scientific name |
Scyliorhinus Blainville, 1816 |
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Genus Scyliorhinus Blainville, 1816 View in CoL
Type species: Squalus canicula Linnaeus, 1758 ; Recent , Northeast Atlantic , Mediterranean, Canary Islands, and Ivory Coast .
Remark.—Many fossil sharks have been affiliated with modern genera with which they have most in common. This is, however, not always desirable, besides having genera ranging for more than 60 Myr, and in the case of Scyliorhinus our knowledge of the inter- and intraspecific variation is limited. This leaves us with the choice of either assigning fossil species to a modern genus or erecting a new genus to contain the fossils with morphology close to a modern genus. Either solution is undesirable and has taxonomic repercussions. We have here continued to use the Recent genus Scyliorhinus in its wide, traditional palaeontological sense, but in quotation marks, rather than to erect new fossil genera prematurely. This problem was aired by Müller and Diedrich (1991) who saw the use of Scyliorhinus as a last resort rather than to be a desirable solution.
“ Scyliorhinus ” elongatus ( Davis, 1887)
Fig. 8A–F View Fig .
Material.— 41 teeth from the Ce of Stevns Kridtbrud ( MGUH 29861–29866 View Materials , GMV2012-71 [batch number]), 35 specimens from the Br1 of Kulstirenden ( GMV2012-72 [batch number]), and a few in a private collection from the Br2 of Faxe. The majority are fragmentary .
Description.—Teeth with a high degree of monognathic heterodonty. Anterior teeth are robust, taller than wide with a prominent main cusp flanked by a pair of cusplets. Lateral teeth are lower and wider.The main cusp is biconvex and with a convex labial face and a very strongly convex lingual face. The cusplets are acute and converging towards the main cusp. Anterior teeth have vertical folds on the cusplets and on the lingual face of the main cusp, whereas lateral teeth also carry vertical folds on the main cusp, both labial and lingual. The crown-root boundary of the main cusp is labially indented. The root is low labially and bilobed with a flat basal face. The lingual face of the root is more prominent than the labial with a strong protuberance with a median foramen. Lingually, below the cusplets, is a foramen present. Posterior teeth are low crowned with up to two pairs of cusplets covered with vertical folds. There is no indentation at the median crown-root junction and in general the posterior teeth are more mesio-distally elongated than teeth from other jaw positions. Teeth reaching 2.4 mm in height and 2.0 mm in width.
Remarks.— Cappetta (1980), in his re-description of the fossils from Sahel Alma ( Lebanon), had several specimens at different ontogenetic stages, but he did not mention teeth with more than one pair of cusplets. However, female and juvenile teeth of the Recent S. canicula frequently have more than one pair of cusplets in more lateral files ( Ellis and Shackley 1995). This can also be observed in S. stellaris JSA , personal observation). S. elongatus is long ranging both from a stratigraphical and a geographic point of view and may represent a species group rather than a single species, much in the same way as Cretalamna appendiculata .
Stratigraphic and geographic range.—Late Cretaceous: Santonian of Lebanon ( Davis 1887; Cappetta 1980), Campanian of England, France, and Belgium (Herman 1977; Vullo 2005; Underwood and Ward 2008) to the late Maastrichtian Morocco ( Noubhani and Cappetta 1997) and the Danian early Paleocene) of Denmark.
“ Scyliorhinus ” biddlei Halter, 1995
Fig. 8G–I View Fig .
1995 Scyliorhinus biddlei sp. nov.; Halter 1995: 77, pls. 1–5, text-figs. –10.
Material.— 22 specimens from the Ce of Stevns Kridtbrud MGUH 29867 View Materials , MGUH 29868 View Materials , GMV2012-73 [batch number]) and six from the Br 1 at Kulstirenden ( MGUH 29869 View Materials , GMV2012-74 [batch number]) .
Description.—Teeth belonging to this species display monognathic heterodonty. Anterior teeth have an elongated biconvex main cusp slightly inclined towards the commissure. The labial face is smooth and convex with some short folds below the shoulders at the crown-root junction. The base of the crown overhangs the root and is deeply indented medially. The shoulders are both inclined labially. The lingual face of the crown is strongly convex and carries folds almost up to the apex of the main cusp, with the most prominent folds being below the shoulders. Roots are missing in all anterior teeth.
Lateral teeth have a prominent elongate main cusp declining towards the commissure and a small distal cusplet. The labial face is convex and smooth, with the exception of the crown-root junction and at the shoulders, which carries short strong vertical folds. The crown overhangs the root. The lingual face of the crown is strongly convex and carries several longitudinal folds on the main cusp and a more reticulated ornamentation on the shoulders. The labial face of the root is low with multiple foramina. The root is bilobed with a flat basal face and a prominent lingual protuberance. There are multiple foramina below the shoulders on the lingual face of the root and foramina in the lingual protuberance. Teeth reaching up to 1.2 mm in height and 1.2 mm in width.
Remarks.—In his description of the type, Halter (1995) states that young individuals have lingual folds on their crowns reaching almost the apex, which is the case for many of our specimens and they are also in general smaller than the specimens described by Halter (1995) (2 mm high and 1.5 mm wide). This suggests that the specimens from Stevns Kridtbrud may have been from juveniles to sub-adults. Interestingly enough, anterior teeth are almost always missing the root, whereas this is not the case of the laterals.
Stratigraphic and geographic range.— Scyliorhinus biddlei is known from the Maastrichtian (Late Cretaceous) of Belgium (Eben-Emael) and the Netherlands ( Halter 1995) and the Maastrichtian (Late Cretaceous) and, Danian (early Paleocene) of Denmark.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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Scyliorhinus Blainville, 1816
| Adolfssen, Jan S. & Ward, David J. 2015 |
Scyliorhinus biddlei
| Halter, M. C. 1995: 77 |