Little is known about the large toothed mitsukurinids. The connection between Scapanorhynchus lewisii and Mitsukurina olsoni is easier as the dentition design is similar and body design is known from the Lebanese chalk. In contrast, S. texanus has much larger teeth, lacks evidence of intermediate files and is known from nearshore waters. Mitsukurina is discussed elsewhere on the website (Scapanorhynchus).

North American reports of the Scapanorhynchus tooth-design include:

  • Morton (1834: 31, pl. 11, fig 2 and possibly 3 & 11); Manning (pers. com. 2008) notes that "From the text (p. 31), it's unclear if two of these teeth (2 & 3) are from New Jersey, Alabama, or South Carolina, but one (fig. 11) is definitely from N.J." (Ref. accompanying Fig. -L.)
  • Morton (1835: 276) would subsequently report that Mantell showed these figures to Agassiz who identified them as Lamna acuminata (pl XI.11) and Lamna plicata (pl XI.2,3). Agassiz (1843) would erect Lamna raphiodon (which was depicted a year later) based on a group of isolated anterior cusps (see Fig. ).
  • Roemer (1849: 52, pl 1 Fig 7) 'described' the generalized tooth-design as Lamna texana (Late Cretaceous, Texas (accompanying Fig. -cR).
  • Gibbes (1849: pl 26, fig 119) reported Lamna contortidens AGASSIZ 1833 (=Scapanorhynchus LA1) from the Late Cretaceous of New Mexico (accompanying Fig. -cL).
  • Emmons (1856: 239, figs 70-71) included Lamna elegans AGASSIZ 1833 (=cf texanus) from the "Miocene" marls of NC (Fig. -R).
  • Williston (1900: 40) appears to have been the first to use Woodward's generic name in NA1; in doing so he synonymized S. texana with S. raphiodon.
  • Although White (1956: 124) used S. texanus when commenting on some of Woodward's (1889) Alabama determinations, Miller (1967:223) attributed Black Creek (NC) teeth to Carcharias? sp & Isurus sp.
  • Meyer (1974: 227-243) included as S. ? raphiodon, Scapanorhynchus teeth lacking short folds on the lower labial crown face (Santonian and older) and as S. ? texanus, teeth with these folds (Campanian and younger).

    East Coast and Gulf. The watershed moment appears to be Cappetta & Case (1975); they attributed these abundant2 NJ Upper Campanian teeth to Scapanorhynchus texanus and provided an excellent series of images (pl 1 13-16, pl 2 fig 1-36) and noted (trans.) "This species most probably derives from S. "raphiodon". Those authors go on to make particular note of the lingual 'tuberculés' (ridges) below the base of the crown. Following their paper, S. texanus has been reported along the East and eastern Gulf coasts by:

  • Case (1979: 80-81) Peedee Fm.(Late Maastrichtian) NC;
  • Schwimmer (1986: 114) Blufftown Fm (Campanian), western GA;
  • Manning & Dockery (1992:28-29) as S. raphiodon texanus from the Frankstown Sand, Demopolis Fm (Late Campanian / Early Maastrichtian), MS;
  • Robb (1992: 79-80) Black Creek Fm.(Campanian), NC;.
  • Hartstein et al (1999) did not recover examples from the Severn Fm (Late Maastrichtian) of MD;
  • Becker et al. (2006) did not report from the Arkadelphia Fm. (Late Maastrichtian).
    Western Interior Seaway. Gibbes' (1849) "Lamna contortidens" (see above) appears to be the earliest report of S. texanus from the (southern) Western Interior Seaway. However, more northerly reported assemblages most often include older horizons than seen on the East Coast and specimens are largely attributed to Scapanorhynchus "raphiodon".
  • Bourdon et al (2011: 25-27) reported S. cf texanus from the Early Santonian of New Mexico. They noted that the teeth generally lacked the ridged necks and basal folds folds seen in the Campanian. The anteriors were nearly identical but the laterals were narrower & more erect, and there may or not be a small secondary cusplet [Compare Campanian (Fig. ) and Santonian (Fig. ) upper first laterals].
    Texas provides an excellent Cretaceous marine fossil record which has been studied extensively over the years.
  • Meyer's (1974: 231-37) earliest report of S. ?raphiodon was from the Uppermost Woodbine Fm (Cenomanian); and latest, from the Austin Group (Lower Coniacian) of Texas. S. ?texanus ranged from the Tombigbee Sand (Santonian) of Mississippi through the Coffee Sand (Upper Campanian) of Mississippi.
  • Welton & Farish (1993: 94-95) include S. "raphiodon" as represented in Turonian-Coniacian sediments and S. texanus from the Campanian-Maastrichtian.
  • Cappetta & Case (1999: 19-21) included S. texanus from the Campanian of Texas.

    Dentition-design

    Based solely on tooth-design (awl-like anteriors and rather broad-bladed laterals) Late Cretaceous Scapanorhynchus teeth appear to have had functionality similar to the extant Shortfin mako; a cutting / clutching dentition optimized for larger teleosts. This is much different than the extant goblin shark with it's awl-like laterals. The actual tooth formula is less clear.
    Relying on Arambourg (1952, pl II & III), captions, he deemed S. rapax to have three upper anteriors and the lower anteriors to be represented by a parasymphyseal (A0) and two anteriors. However, based on lateral profile, one of his figured UA3's (pl II, fig 3) is clearly a lower tooth not represented by his LA1 & LA2 figures. The resulting tooth-formula (Fig. ) would represent 3 upper and 4 lower anteriors as seen in the extant taxon.
    Cappetta & Case (1975) provided a good set of S. texanus images, but other than the A1 positions, they figured no lateral profiles in association with other perspectives; their captions (and text) made no positional assignments other than anterior vs. lateral. The tooth they proposed as the parasymphyseal (aka A0; pl 2, fig. 7) was only a lateral profile which was not lingually directed (more likely an upper tooth). Another figure (pl 2, fig 30) was only imaged laterally but could have been an A0. Based on root-design, another tooth (pl 2, fig 23) did not compare well with other upper laterals (?Serratolamna serrata) and was excluded from consideration. The resulting arrangement (Fig. ) better defines the lateral hollow than Arambourg's images, but is less definitive with the anterior hollows.

    Herman (1977) provided another group of excellent multi-perspective images, in this case, S. raphiodon. The positions represented are less than the other authors, but they clearly depict three 'significant' lower anteriors (ref. Fig. ).

    Tooth-Design

    The Late Cretaceous representative of the genus in the Mid-Atlantic States, S. texanus is characterized by strongly striated awl-like anterior teeth (Figs. - ) and usually distinctive laterals (Figs. - ). The anteriors can be broadly described as having slender and elongated bilobate roots that have a lingual protuberance with a short but deep groove. The crowns are long and narrow with distinct striations; lateral cusplets may be present based on position. The lateral teeth have broader roots, and the crowns can be nearly smooth or have weak (lingual) striations, and bear one or more lateral cusplets. The neck of anterior and upper teeth bear closely spaced lateral ridges which appear to merge near the base of the crown, joining to form the strong lingual striations (when present).
    Anteriors. The first anterior position is relatively erect, lacks cusplets and has a mesodistally-compressed root. The second anterior is more distally inclined, may or may not have small pair of single cusplets and has more splayed roots. In the third position the cusp is shorter, distally inclined but may be mesially recurved, single cusplets are more common and the root lobes more greatly splayed. In each position, the lower tooth tends to be more lingually directed than its upper counterpart; the latter's cusp tends to be sigmoidal in profile.

    Laterals. The laterals tend to have moderately broad and smooth lingual crown faces although they may bear striations particularly laterally. Cusplet pairs (larger medial, smaller lateral) are present and the root is much more robust than seen in extant goblins. Upper teeth are more distally inclined and labially curved than their lower counterparts that are more erect. There appears to be propensity for the uppers to become progressively more inclined distally. Lower teeth remain quite erect, but become shorter distally.

    Contrasting the dentition-design of Scapanorhynchus texanus with that of Mitsukurina owstoni, the greatest difference can be seen in the upper laterals in which the former's cutting-design (broad and cuspleted crowns) are simply narrow grasping-like teeth in the latter.


     

    Acknowledgements

    I need to thank Tom Caggiano, Kim Greene & Howie Cohn for providing specimens, Roberta Dann for her help with the original page, Pieter DeSchutter & David Ward for modern literature, Mikael Siverson for his insight & comments and Earl Manning for obscure literature, obtaining comparative material & observations on the topic.

    Footnotes

    1.   Manning (pers com 2008) notes: "The first published report of American fossil material as Scapanorhynchus is Williston (1900, pp. 251-2 [in part], pl. 24, figs. 2-2a [after Leidy, 1873, pl. 18, figs. 48-9]; not pl. 26, figs. 2 & 4, or pl. 32, figs. 4-5), from the lt. Santonian of Mississippi, which Leidy had called Lamna sp and Williston half-correctly called S. raphiodon."
    2   Lauginiger (1986: 55) provided some interesting statistics on the abundance of these teeth while screening Big Brook, (Late Campanian, NJ). Over a five year period, students collected 3500+ teeth using a 1/4" mesh; of these, 55% represented Squalicorax and 19% Scapanorhynchus.

    Selected References

     

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