The teeth of this genus represent a heterodont dentition in which the roots become more flattened, elongated and rectilinear distally, while the smooth cusps become more flattened and triangular. The genus has at times been placed in (Leriche 1905 & Casier 1958), (Glikman 1964) and (Cappetta 1987, Kent 1994, Case & Borodin 2000). It is difficult to recognize the characteristics which would support attributing these teeth to any of these families.

The roots of the anteriors and antero-laterals show short, but distinct, branching lobes. The cusp of the anterior teeth are mesial-distally compressed, labio-lingually expanded and bear cutting-edges on the labial and sometimes lingual faces. The cutting-edge of the antero-laterals (and laterals) runs along the mesial and distal margins of the cusp.

Lateral teeth are strongly compressed labio-lingually,distally inclined and bear a short distal heel. The root has a flat basal margin and face, the latter bears a circular foramen.

Cappetta (1987: 97) noted three species and attributed them to deep-water deposits:

  • The type species, Xiphodolamia ensis LEIDY 1877 (Lower Eocene), is from New Jersey marls and has been found elsewhere in North America, the UK and Kazakhstan.
  • X. barbadica (CASIER 1958) has been reported from the Middle Eocene of the West Indies, and
  • X. eocaena (WOODWARD 1889) from the Lwr Eocene (Ypresian ) England & Denmark and the Mid Eocene (Lutetian) of Belgium.
    The genus had also been reported from the Middle Eocene of West Africa.

    In a study of this genus, Adnet et al (In Press) included Xiphodolamia in and synonymized X. barbadica and eocaena with X. ensis. In addition, they erected X. serrata for serrate examples from the Late Eocene of Africa and the Middle East. These authors provided excellent positional descriptions for X. ensis, acknowledged an inability to differentiate uppers from lowers and proposed certain positional placements (including a parasymphyseal and "intermediate").

    Along the east coast of North America, the few published reports include: Leidy 1877: Xiphodolamia ensis (Lower Eocene) of New Jersey, Kent (1994: 63) Xiphodolamia ensis Nanjemoy Fm (Lower Eocene) of the Chesapeake Bay area and Case (2000: 24) Xiphodolamia sp (based on two very worn specimens) from Castle Hayne Fm (Middle Eocene) NC.


     

    Selected References

    Adnet, S., R. Hosseinzadeh, M. Antunes, A. Balbino, V. Kozlov and H. Cappetta, In Press. Review of the enigmatic Eocene shark genus Xiphodolamia (Chondrichthyes, Lamniformes) and description of a new species recovered from Angola, Iran and Jordan. Journal of African Earth Sciences, 2009.
    Cappetta, H., 1987. Chondrichthyes II: Mesozoic and Cenozoic Elasmobranchii. Handbook of Paleoichthyology, 3B. Gustav Fischer Verlag, Stuttgart and New York, 193 pp.
    Case.G. & Borodin, P., 2000. A Middle Eocene Selachin Fauna from the Castle Hayne Limestone Formation of Duplin County, NC, Munchner Geowiss. Abh.. 39:17-32.
    Casier, E., 1958. Contribution à l'étude des poissons fossiles des Antilles. Schweis. Pal. Abl., no 74, 95pp.
    Glikman, L., 1964. Class Chondrichthyes, subclass Elasmobranchii. In: Fundamentals of Paleontology, Academii Nauk SSSR, 11:292-352.
    Leidy, J., 1877. Description of vertebrate remains, chiefly from the phosphate beds of South Carolina. Journal of the Academy of Natural Sciences, Philadelphia, 8 (series 2): 209-261.
    Leriche, M., 1905. Les poissons tertiaires de la Belgique. II. Les poissons éocènes. Mém. Mus. Roy. Hist. Natur. Belg., 11(3): 49-228.
    Kent, B. 1994. Fossil Sharks of the Chesapeake Region. Egan Rees & Boyer, Maryland, 146 pp.
    Woodward, A., 1889. Catalogue of the fossil fishes in the British Museum. Part. I.: British. Museum (Natural History), 474 pp.

     

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