Extant sandtigers are large (reaching 3.5 m), usually bottom dwelling sharks of continental and insular shelves in temperate and tropical seas. Sandtigers, alone or in groups, feed on bony fishes, other sharks & rays, squid and crustaceans. The grasping-cutting dentition is characterized by 2 or 3 awl-like anterior teeth, one or more smaller intermediates (upper), a series of shorter & broader laterals and numerous small posterior teeth. According to Compagno (2001: 58-62), the common living species is the Largetooth sand tiger, C. taurus (RAFINESQUE, 1810). It has a scattered distribution, reported from temperate - tropical waters of the Atlantic and Indo-West Pacific shelf from the surf to 191 m. The Indian sand tiger, C. tricuspidatus (DAY, 1878) (?syn C. taurus) is a poorly known inshore & offshore (to 1600 m) species from the Indian Ocean (possibly extending into Western Pacific). Over the years, these species have bounced between various genera (Eugomphodus GILL, 1861, Synodontaspis WHITE, 1931 & Carcharias), leading to some confusion.
The dentition of Carcharias taurus has been extensively studied and is well known. The anterior teeth have long and slender cusps (sigmoid in profile) with lateral cusplets. The lingual face is strongly convex and bears irregular folds. The labial face is flat and smooth and the cutting edge is incomplete. The root is high with well-separated lobes, a prominent lingual protuberance and sharp nutrient groove. The lateral teeth are shorter, broader (particularly at the base) and flatter (more blade-like), and bear a cutting-edge which reaches the lateral cusplets (one or two pair). The strong folds or wrinkles seen in anterior teeth weaken significantly or disappear. The root lobes are more widely separated and the root-face flatter. Well over a dozen posterior files are present (per side). These teeth are short and relatively thick and gradate distally from a low cusp with lateral cusplets to a non-cuspidate design.
Fossil teeth, sometimes from isolated positions and at other times intermixed, have formed the basis for new species. The quantity of described taxa is overwhelming, so the focus will be limited to Eastern North America.
Cappetta & Case (1975a,b) erected four species, Carcharias amonensis & C. tenuiplicatus from the late Lower to early Upper Cretaceous Interior Sea area of Texas and C. holmdelensis & C. samhammeri from the late Upper Cretaceous of the East Coast.
Case (1987) erected Odontaspis cheathami for a sand tiger tooth-design from the Late Campanian of Wyoming. Case & Cappetta (1997: 141) moved this design to Carcharias and noted, "So. C. cheathami and C. holmsdelensis appear to be very close, if not identical species". They do note that the latter's anteriors tend to be more slender with smaller cusplets. This tooth design is included below as ?holmsdelensis.
Welton & Farish (1993: 89-90) included C. amonensis as Late Albian - Cenomanian and C. tenuiplicatus as Cenomanian only.
Kent (1994: 39-43) noted both C. holmdelensis & C. samhammeri as being present in the Campanian - Maastrichtian of New Jersey & Delaware (Marshalltown, Mt. Laurel & Severn Fm) and the former in Georgia as well.
Welton & Farish (pp 91-92) also noted additional undescribed sand tiger-type teeth in the Texas fauna. Case & Cappetta (1997: 140-41) reporting on the Kemp Clay (Maas. TX) included C. holmdelensis & C. samhammeri and erected C. heathi for a smooth crown tooth-design.
Glikman and Averianov (1998) argued, that based on positional tooth-counts, Cretaceous sandtigers from the Russian platform could not support an assignment to the extant genus (Carcharias) and used Eostriatolamia for their studied material; they went on to comment that some North American taxa might belong to that genus as well — E. amonensis?, E. holmdelensis and E. samhammeri?.
Cappetta (2006) includes Eostriatolamia, but applies it to E. venusta (LERICHE, 1906c) and taxa from the Russian platform; not to North American sandtigers.
Becker et al (2006: 705) reported C. cf holmdelensis from the Arkadelphia Fm. (Maastrichtian) of Arkansas.
Elasmo.com (2010) adopts usage of Eostriatolamia for certain sandtigers from North America; moving E. holmsdelensis and E. amonensis.
Bourdon et al (2011: 27-29) reported Carcharias sp. from the Pt Lookout Ss. (Santonian) of New Mexico.
Over the years, a number of species have been attributed to Carcharias and reported from the western North Atlantic.C. whitei (ARAMBOURG, 1952) - Palaeocene [Brightseat Fm]
C. hopei (AGASSIZ 1843) - Late Palaeocene - Eocene [Aquia, Nanjemoy & Piney Pt Fm]
C. acutissima (AGASSIZ, 1844) - Late Eocene [Piney Pt Fm]
Ward & Wiest (1990: 84) included in their Paleogene fauna of the Chesapeake Bay (MD & VA):
Kent (1994) went on to include in this fauna:
C. teretidens WHITE, 1931, - Late Palaeocene - Eocene [Aquia Frm]
C. robusta? (LERICHE, 1921) - Early Eocene
Müller (1999: 36-38) reported C. hopei from the Piney Pt Fm., C. vincenti (WOODWARD, 1899) from the Aquia & Nanjemoy and Hypotodus verticalis (AGASSIZ 1843). Elasmo.com (1999) went on to add C. koerti (STROMER 1905) to this Western Atlantic fauna; finally documented by Parmley et al (2003).
Cappetta & Nolf (2005) did a revisionary study of Paleogene sand tigers of Europe. This paper's reassignments significantly affects their Western Atlantic counterparts and also required the reassignment of the koerti-design on the website.
C. hopei see: Hypotodus verticalis
C. teretidens see: Sylvestrilamia teretidens
C. robusta see: Jaekelotodus robustus
Cappetta & Nolf discuss a previously undescribed Carcharias-like species that they tentatively refer to as Carcharias sp. These striated teeth (see Fig. ) are commonly encountered in the Paleogene of Europe (de Schutter pers com 2005) and anecdotally referred to as C. acutissima (based on their similarity with that taxon). Some teeth from the Eocene of the Chesapeake Bay area compare well with this new taxon and may be present in the Nanjemoy fauna. In addition, the Nanjemoy yields other Carcharias-like teeth (see Fig. & ) that don't fit into the tooth-designs associated with the previously mentioned taxa.
Out of scope for their study were the teeth referred to as "Carcharias koerti", long known from the Eocene sediments of Dixie. The Cappetta & Nolf revised definition of Carcharias would most certainly not include this tooth-design if considered; elasmo.com has determined it better belongs in Serratolamna.
Neogene sand tigers of the Western North Atlantic seem to be no less bewildering to paleontologists than their Paleogene counterparts had been.
Kent (1994: 39-43) summarized the Neogene Carcharias taxa of the Chesapeake area as:
C. acutissima (AGASSIZ 1843), Oligocene - Pliocene
C. reticulata (PROBST, 1879), Oligocene - Miocene
C. cuspidata (AGASSIZ 1843), Oligocene - Miocene
C. taurus (RAFINESQUE, 1810), Pleistocene
Müller (1999: 36-38) reported C. acutissimus as Oligocene-Pliocene and C. cuspidatus as Miocene - Pliocene.
Purdy et al (2001:101-104) concerned themselves with the Lee Creek fauna only and included:
C. taurus RAFINESQUE 1810 , Pliocene - Pleistocene
C. cuspidata (AGASSIZ 1843), Pliocene - Miocene
C. sp (similar to C. contortidens (AGASSIZ 1843), Miocene
Odontaspis cf O acutissma (AGASSIZ 1843), Miocene. Their figured teeth appear to be those referred to by Kent (1994) as C. reticulata and on this website as O. reticulata.
Until the experts reconstruct these dentitions following the methodology proposed by Cunningham (2000), all of these identifications must be called into question or at least treated with extreme caution.
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