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 denticles (spines) have a dorso-ventrally compressed crown (cap) 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 & Interior Sea) reported occurrences include:

  • Slaughter & Steiner (1968: 268) attributed their Late Cretaceous Texas rostral spines to S. atavus.
  • 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 denticles of this taxon have a strongly-barbed posterior profile. (Note the high root relative to those of S. fanninensis.)
  • 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 denticles. 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
  • Becker et al (2006:707) reported Sclerorhynchus sp from the Maastrichtian of Arkansas.

    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
    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. R., and H. Cappetta. 1997. A new selachian fauna from the late Maastrichtian of Texas. Muünchener Geowissenschaften Abhandungen 34:131-189.
    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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