Guitarfish are benthic batoids inhabiting warm, shallow waters, of the continental shelf. The genus Rhinobatos is represented by 26 living species, only two of which can be found off the East Coast of the United States (from North Carolina south) - R. percellens (WALBAUM 1792) and R. lentiginosus GARMAN 1880. Two other species inhabit California waters - R. productus GIRARD 1855 and R. glaucostigma JORDAN & GILBERT 1883. The dentition is of a crushing design, incorporating hundreds of juxtaposed small teeth.

Dating to the Lower Jurassic, guitarfish are a relatively conservative chondrichthyan family. Unlike so many batoids, the rhinobatid genera are well represented by fossil skeletons and evolutionary changes have been noted in body design, but not the teeth. Cappetta (1987:137) included nine genera as being represented in the fossil record, but only one Rhinobatos, as represented in North American deposits.

The teeth of the species are very small and usually require mesh sizes of 1.2 mm or less to be recovered. The teeth appear to have a rather globular crown, but magnification reveals a transverse ridge and strong lingual & relatively strong lateral, uvulae. The roots extend beyond the lingual face of the crown, and when viewed basally, narrow lingually and have a strong nutrient groove. The lateral faces of the root are strongly notched and usually reveal the associated margino-lingual foramina.

Reports from North America include (there are more):

  • Cappetta (1973) described Rhinobatos incertus for teeth from the Turonian of South Dakota.
  • Cappetta & Case (1975:25-26) included R. casieri as from the Campanian of New Jersey.
  • Case (1981: 68, pl 3.9) included as R. cf casieri a single tooth from the Twiggs Clay, Barnwell Fm (Late Eocene) of Georgia.
  • Manning & Standhardt (1986:146) included as R. cf casieri guitarfish teeth from Yazoo Clay (Priabonian) of Louisiana.
  • Welton and Farish (1993:131) included R. casieri (Campanian) and R. incertus (Turonian-Coniacian) in the Cretaceous of Texas.
  • Williamson et al (1993:458; fig. 8) included Rhinobatos sp in the Cenomanian-Turonian of Arizona.
  • Case & Cappetta 1997 erected two new species based on teeth from the Maastrichtian of Texas.
    - R. uvulatus (p146; pl 11.4) included the tooth-design (short marginal uvulae) reported by Cappetta & Case (1975) and Welton & Farish (1993:131, fig 1-4) as R. casieri, and
    - R. craddocki (p146; pl 12.8) which had no marginal uvulae.
  • Hartstein et al (1999:18) included as Rhinobatos sp teeth from the Severn Fm. of Maryland.
  • Müller 1999:55 reported teeth from the Piney Point Fm (Ypresian) of Virginia as R. aff bruxelliensis JAEKEL 1894.
  • Kent (1999:39) included guitarfish teeth from the Nanjemoy Fm (Ypresian, VA) as R. bruxelliensis.
  • Cappetta & Case 1999 erected three new species from the Late Cretaceous of Texas.
    - R. kiestensis (p31; pl 19.1-3) Turonian-Coniacian
    - R. ladoniaensis (p31; pl 18.6-7 Lower Campanian
    - R. lobatus (p32; pl 18.1-5) Turonian-Coniacian
  • Purdy et al (2001:89) attributed Lee Creek guitarfish teeth (Pungo River, Units 4,6 - Middle Miocene) as Rhinobatos sp. Teeth of this design are included on this website as Rhynchobatus.
  • Shimada & Fielitz (2006:197) included Rhinobatos sp. in the Niobrara of Kansas.
  • Shimada et al (2006:18) reported Rhinobatos sp. from the Greenhorn Ls of Colorado.
  • Bourdon et al (2011:40) included Rhinobatos sp. is the Santonian of New Mexico.
  • Hamm & Cicimurri (2011:120) included as Rhinobatos lobatus, guitarfish-like teeth from the Atco Formation (Early Coniacian) of Texas.

    The teeth of Rhinobatos casieri have a high crown and relatively strong transverse ridge. The lingual uvula is strong and the lateral uvulae less extended. The tooth's enameloid is smooth and the labial visor is convex in profile. Anterior to the transverse ridge, there are weak depressions on either side of the crown. The central pore is large and the margino-lingual foramina, usually distinct.

    Cappetta (1987:137) listed two Eocene species from Western Europe, R. bruxelliensis (JAEKEL 1894) and R. steurbauti CAPPETTA & NOLF 1981 but none from North America. Insufficient information has been located to suggest a positive identification for the below Nanjemoy specimens


     

    Selected References

    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., 1973. Selacians of the Carlile Shale (Turonian) of South Dakota. Journal of Paleontology, 47(3) pp 504-514.
    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., 1975. Contribution à l'étude des sélaciens du groupe Monmouth (Campanien - Maestrichtian) du New Jersey. Palaeontographica Abteilung A, 151:1-46.
    Case, G., 1981. Late Eocene selachians from South-Central Georgia. Palaeontographica Abt. A, 176: 52-79.
    Case, G. and Cappetta, H.. 1997. A new selachian fauna from the late Maastrichtian of Texas. Münchener Geowissenschaften Abhandungen 34:131-189.
    Everhart, M.J., 2007. New stratigraphic records (Albian-Campanian) of Rhinobatos sp. (Chondrichthyes; Rajiformes) from the Cretaceous of Kansas: Transactions of the Kansas Academy of Science, v. 110, p. 225-235.
    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.
    Hartstein, E., Decina, L. and Keil, R., 1999. A Late Cretaceous (Severn Formation) Vertebrate Assemblage from Bowie, Maryland. The Mosasaur, 6:17-23.
    Kent, B. 1999. Sharks from the Fisher/Sullivan Site. In: Weems, R. & Grimsley, G., Early Eocene Vertebrates and Plants from the Fisher/Sullivan Site (Nanjemoy Formation) Stafford County, Virginia. Virginia Division of Mineral Resources, Pub 152: 11-37.
    Manning, E. and Standhardt, B., 1986. Late Eocene sharks and rays of Montgomery Landing, Louisiana. In: Schiebout, J. and van den Bold, W. (eds), Montgomery Landing site, marine Eocene (Jackson) of central Louisiana:. Gulf Coast Accoc. of Geo. Societies<, Symposium Proceedings pp 133-161.
    Müller, A. 1999. Ichthyofaunen aus dem atlantischen Tertiär der USA. Leipziger Geowissenschafteb, Leipzig, 9/10: 1-360.
    Purdy, R., Schneider, V., Appelgate, S., McLellan, J., Meyer, R. & Slaughter, R., 2001. The Neogene Sharks, Rays, and Bony Fishes from Lee Creek Mine, Aurora, North Carolina. In: Geology and Paleontology of the Lee Creek Mine, North Carolina, III. C. E. Ray & D. J. Bohaska eds. Smithsonian Contributions to Paleobiology, No 90. Smithsonian Institution Press, Washington D.C. pp. 71-202.
    Shimada, K. and Fielitz, C., 2006. Annotated checklist of fossil fishes 2from the SSmoky Hill Chalk of the nobrara Chalk (Upper Creeaceous) in Kansas. NMMNH Science Bulletin 25; pp 193-213
    Shimada, K., Schumacher, B., Parkin, J. and Palmero, J., 2006. Fossil Marine vertebrates from the lowermost Greenhorn Limestone (Upper Cretaceous: Middle Cenomanian) in southeastern Colorado. Journal of Paleontology, 80(2 II) pp 1-45.
    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.
    Williamson, T., J. Kirkland and S. Lucas, 1993. Selachians from the Greenhorn cyclothem ("Middle" Cretaceous: Cenomanian-Turonian), Black Mesa, Arizona, and the paleogeographic distribution of Late Cretaceous selachians. Journal of Paleontology 67(3), pp 447-474.

     

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