Similar to extant sawfishes (), Sclerorhynchus had a flattened shark-like body with a spine-edged rostrum. They are represented in Late Cretaceous fossil records of the Tethys region and North America. S. atavus WOODWARD 1889 is known from complete skeletons (to 1 meter in length) from the Late Santonian of Lebanon.

The skin-mounted rostral spines have a dorso-ventrally compressed cap (crown) which broadens basally and anterior/posterior cutting edges; depending on species. The peduncle (root) is shorter than the crown, bilobate and the dorso-ventral faces weakly undulated.

The oral teeth are small (1.5 mm class) representing a durophagous crushing dentition. The crowns are generally triangular and stout with a short but distinct cusp. The labial face projects beyond the roots and bears meandering apically directed ridges. The lingual face is smooth (without magnification) with a sometimes weak uvula. The roots are broader than the crown and when viewed basally, the lobes are triangular and separated by a parallel groove.

In North America (East/Gulf Coast & Western Interior Seaway) reported occurrences include:

  • Slaughter & Steiner (1968: 268) attributed their Late Cretaceous Texas rostral spines to S. atavus.
  • Meyer (1974: 101-11) attributed four rostral spine designs to Sclerorhynchus from Texas and the Gulf Coast:
    - Sclerorhynchus atavus Santonian-Campanian of Mississippi & Texas
    - Sclerorhynchus sp.1 Santonian of Texas (=S. priscus below; also similar to Figs. & below).
    - ?Sclerorhynchus sp.2 Sant. MS (=Borodinopristis schwimmeri CASE, 1987).
    - Sclerorhynchus sp.3 Campanian of Mississippi (=S. pettersi below).
  • Welton & Farish (1993: 146) included this design as Sclerorhynchus sp. in reporting on their Texas material (Coniacian-Campanian).
  • Case and Cappeta (1997: 148, pl 12.5-6) erected S. pettersi (fig. - below), for rostral & oral material from the Kemp Clay (Late Maastrichtian), TX. The rostral spines of this taxon have a strongly-barbed posterior profile. (Note the high root relative to those of S. fanninensis.) They also included an image (149, text fig 8) an example from the Late Maastrichtian of NJ.
  • Cappetta & Case (1999: 36-37) erected S. fanninensis (fig. & below, which included: Slaughter & Steiner's (1968) S. atavus, Meyer's (1974) S. atavus, and Welton & Farish's S. sp) for (Lower Campanian) oral teeth and rostral spines. SEM images clearly show the pitted occlusal surface which Cappetta (1987: 155-56) uses to differentiate these NA specimens from those of Lebanon.
  • Cappetta & Case (1999: 37) also erected S. priscus [which included Meyer's (1974: 107) S. sp. 1] for Turonian-Coniacian teeth from Dallas Co., TX.
  • Becker et al (2004:788) reported Sclerorhynchus sp from the Maastrichtian of South Dakota
  • Kriwet (2004) wrote that using cladistic principles and phylogenic analysis, appeared to represent a sister group to the Pristiformes and proposed the order Sclerorhynchiformes.
  • Becker et al (2006:707) reported Sclerorhynchus sp from the Maastrichtian of Arkansas.
  • Bourdon et al (2011:37) reported Sclerorhynchus sp from the E-M Santonian of New Mexico. Without oral teeth, the authors lacked evidence to choose between S. atavus and S. priscus. (See Figures & below.)
  • Hamm & Cicimurri (2011:118) included S. cf priscus in the Atco Formation (Early Coniacian) of Texas.

    S. pettersi vs S. fanninensis. Viewing the above rostral spine examples of S. pettersi (Maas., Fig. ) and fanninensis (Camp., Fig. , Cappetta & Case 1999 tendered no examples of the latter's oral teeth), the spine-designs do appear different; the former has a distinct barb and bears striations (not mentioned in the description) while the latter is more S. atavus-like with a posterior bulge and smooth crown. In the Campanian-Maastrichtian of Mississippi, these characteristics appear less relevant. Figure depicts a Late Campanian smooth-cusped barbed spine and Figure a non-barbed example form the M-L Maastrichtian. Reworked examples (?Maas) depict smooth but also striated (Figs & ) cusps with varying posterior edges. In the Campanian-Maastrichtian of Mississippi fauna, this rostral spine design appears more chronologically variable than indicated by Cappetta & Case suggesting a single species (or more than proposed by them). Because S. pettersi has priority over S. fanninensis and is represented by oral and more numerous rostral examples, all the Mississippi specimens are included herein as S. cf pettersi.

     

    Selected References

    Becker, M., Chamberlain, J. and Terry, D., 2004. Chondrichthyans from the Fairpoint Member of the Fox Hills Formation (Maastrichtian), Meade County, South Dakota. Journal of Vertebrate Paleontology, 24(4):780-793,
    Becker, M, Chamberlain, J and Wolf, G., 2006. Chondrichthyans from the Arkadelphia Formation (Upper Cretaceous: Upper Maastrichtian) of Hot Spring County, Arkansas. Journal of Paleontology; 80:4; pp 700-716
    Bourdon, J., Wright, K., Lucas, S.G., Spielmann, J.A. and Pence, R., 2011. Selachians from the Upper Cretaceous (Santonian) Hosta Tongue of the Point Lookout Sandstone, central New Mexico. New Mex. Mus. Nat. His. and Sc., Bulletin 52; 54pp.
    Cappetta, H., 1987. Chondrichthyes II. Mesozoic and Cenozoic Elasmobranchii. In: Handbook of Paleoichthyologie, vol. 3b, Gustav Fischer Verleg, Stuttgart, 193 pp.
    Cappetta, H. and Case, G., 1999. Additions aux faunes de sélaciens du Crétacé du Texas (Albien supérieur-Campanien). Palaeoichthyologica, 9, 5-111.
    Case, G., 1987. Borodinopristis schwimmeri, a new Ganopristine sawfish from the Upper Blufftown Formation (Campanian) of the Upper Cretaceous of Georgia. Bull. NJ Acad. Sci, 32:1, pp 25-33.
    Case, G. R., and H. Cappetta. 1997. A new selachian fauna from the late Maastrichtian of Texas. Muünchener Geowissenschaften Abhandungen 34:131-189.
    Hamm, S.A. and D.J. Cicimurri, 2011. Early Coniacian (Late Cretaceous) selachian fauna from the basal Atco Formation, Lower Austin Group, north central Texas; Paludicola [Rochester Institute of Vertebrate Paleontology] 8(3):107-127.
    Kriwet, J., 2004. The systematic position of the Cretaceous sclerorhynchid sawfishes (Elasmobranchii, Pristorajea) In: Mezozoic Fishes 3 - Systematics , Palaeoenvironments and Biodiversity. Arratia & Tintori (eds.); Pfeil, Germany. pp 57-73.
    Meyer, R., 1974. Late Cretaceous elasmobranchs from the Mississippi and East Texas embayments of the Gulf Coastal Plain. Unpubl. PhD dissertation, Southern Methodist Univ., Dallas, xiv+419 p.
    Slaughter, B and Steiner, M. 1968. Notes on the Rostral teeth of Ganopristine Sawfishes, with special reference to Texas material. Paleontological Notes. Journal of Paleontology, 42(1) pp 233-239.
    Welton, B. and Farish, R., 1993. The Collector's Guide to Fossil Sharks and Rays from the Cretaceous of Texas. Before Time, Texas. 204 pp.
    Woodward, A., 1889. Catalogue of the fossil Fishes in the British Museum. Part I. - XLVII. Brit Mus. Nat. Hist. 474 pp.

     

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