Squalicorax coquandi, Vullo & Cappetta & Néraudeau, 2007
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publication ID |
https://doi.org/ 10.5281/zenodo.13741981 |
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persistent identifier |
https://treatment.plazi.org/id/03A787AC-1654-FFAE-F216-836BCB93FAAD |
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treatment provided by |
Felipe |
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scientific name |
Squalicorax coquandi |
| status |
sp. nov. |
Squalicorax coquandi sp. nov.
Fig. 2E View Fig .
Holotype: Specimen UM PDB 1 .
Derivation of the name: Species named in memory of Henri Coquand (1811–1881), for his work on the palaeontology of the Cretaceous of Charentes (1859).
Type locality: Port−des−Barques, Charente−Maritime.
Type horizon: Lowermost Turonian, base of subunit T1, lithological unit T 1m.
Material.—One complete tooth. Only known from the type locality.
Diagnosis.—This large−sized species of Squalicorax is easily distinguishable from all other species of the genus by its tooth morphology, characterized by an acute, slim cusp showing subrectilinear edges (according to the single available specimen). The cutting edges are very finely and regularly serrated. There is a clear and rounded distal notch.
Description.—The single but perfectly preserved specimen (UM PDB 1; Fig. 2E View Fig ) is 22 mm high and probably corresponds to an antero−lateral tooth, slightly broader than high. This tooth has a narrow, slim and acute cusp, bent toward the rear. The edges are practically straight: the mesial one is very slightly convex and the distal one very slightly sigmoid. The distal notch is rather open (110 °) and is both clear and slightly rounded. The distal heel, well developed, is long, oblique, and almost rectilinear. The cutting edge serrations are very fine and very regular. The basilo−labial bulge of the crown is not very prominent and disappears laterally. The root is rather high and not very thick, with lobes separated by a broad median concavity. It displays a series of foramina under the labial bulge of the crown.
Remarks.—It is sure that the definition of a new species based on a single tooth can be discussed and criticized. However, it is important to note that the species of Squalicorax are generally characterized by a weak gradient monognathic and dignathic heterodonty (see Welton and Farish 1993). Thanks to this relative homodonty, one tooth can be enough to display the diagnostic dental features of a species. In this precise case, the holotype is perfectly preserved and clearly different from all other previously described species. A second specimen, unfortunately lost, has also been studied. This large−sized species seems to be very rare. Collecting additional specimens may take a lot of time. So, it seems to us that the description of this new taxon is justified.
By its tooth morphology, Squalicorax coquandi sp. nov. differs clearly from the other described species of the genus. However, Antunes and Cappetta (2002: pl. 7: 6–8) have figured, under the name of Squalicorax sp. , some teeth from the Upper Turonian of Iembe ( Angola) showing similarities with S. coquandi sp. nov. (narrow and acute cusp, subrectilinear edges). These teeth, however, differ in their smaller size and in having a more acute and angular distal notch. The large size of teeth of S. pelagicus sp. nov. is unlike that of other Squalicorax of earliest Turonian age. The analogy existing between the teeth of Squalicorax and the upper teeth of some large pelagic species of Carcharhinus Blainville, 1816 was underlined by Cappetta and Case (1999). If the teeth of S. falcatus , with a broader and more robust crown, can be compared for example with those of C. longimanus Poey, 1861 , S. coquandi sp. nov. reminds by its more sharp teeth another oceanic species, C. falciformis Müller and Henle, 1841 . It also reminds the tooth morphology of the genus Sphyrna Rafinesque, 1810 .
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