In 1991, Landemaine erected a new genus (and family) to include certain Cretaceous and Paleogene (aschersoni-gafsana-koerti lineage) Cretalamna-like teeth that displayed asymmetrical lateral cusplet groups and a weak nutrient groove. This determination has not been universally accepted; for example, Cappetta (2006) accepts the Cretaceous determination but continues to include the Paleogene lineage as "Cretolamna". Kent (1994) adopted Serratolamna for lerichei teeth (followed by elasmo.com); however, Cappetta & Nolf (2005) deemed lerichei to be an odontaspid and erected Brachycarcharias for these teeth. At this time (2007), elasmo.com includes lerichei in Brachycarharias based on Cappetta & Nolf (2005); this may or may not be a correct determination. Cappetta (2006) provided no arguments to support his determination that the aschersoni-gafsana-koerti lineage should be included in Cretalamna and elasmo.com can only reject this "proclamation".

Three species have been reported from Mid-Atlantic sediments:

  • Serratolamna serrata (AGASSIZ 1843) is a Cretaceous species known from the Chesapeake, North Carolina and into Texas.
  • Case (1981:58-59) erected Lamna twiggsensis for a tooth-design from the Eocene of Georgia; these teeth are identical to Serratolamna koerti (STROMER 1910) and can only be viewed as a junior synonym of the latter.
  • Case (1994:114) reported "Cretolamna" aschersoni (STROMER 1905) from the Late Palaeocene/Early Eocene of Mississippi while Kent (1994:53) included this tooth-design as Serratolamna from the Eocene of the Chesapeake region; it would appear that these teeth may in fact be S. gafsana (see below).

    The teeth from this genus can be best characterized as being an asymmetrical Cretalamna-type tooth with multiple cusplets. The crowns are smooth with a complete cutting edge. One to three cusplets are present with distal cusplets often outnumbering mesial. The roots have a V-shaped basal margin, weak nutrient groove and distinct foramen. In general, the cusp is an elongated triangle that is distally directed (anterior teeth are nearly erect).

    Welton & Farish (1993: 112) included a lateral tooth identified as S. serrata which looks very much like those of Cretalamna biauriculata maroccana ARAMBOURG 1935 and is unlike other teeth of S. serrata. This is possibly a dignathic variation; however this design is symmetrical with a significantly broader, shorter and erect cusp. (ref. C. biauriculata illustration). Figure depicts a tooth from Castle Hayne (redeposited Cretaceous?) that shows differences with C. biauriculata illustrations (cusplets not splayed, small foramen) and the tooth image in the Cretalamna section.

    Uncommon in Nanjemoy (Eocene) exposures are the large teeth of Serratolamna gafsana. These have been often incorrectly identified in the past (including on this page) due to their identification as aschersoni in Case (1994). David Ward (pers. com. 1998), when confirming Steve Cunningham's (pers. com. 1998) suggestion that these might represent S. gafsana, noted that the illustrations in Arambourg (1952) clearly show that the teeth of aschersoni have a shallow root and "bizarre" lateral cusplets. David went on to note that juvenile S. gafsana teeth are Carcharias-like with multiple lateral cusps, fine striations on the labial face.

    Relatively Common in the Castle Hayne (Lutetian & Bartonian) sediments of North Carolina are the teeth of S. koerti; these teeth appear equally abundant in comparable horizons of other southeastern states extending into Texas. Although present in the Chesapeake Bay area, they are scarce.

    References

    Arambourg, C., 1952. Les Vertébrés fossiles des Gisements de Phosphates (Maroc-Algére-Tunisie), - Service Géol. Maroc, Notes et Mém., 92, pp 1-372.
    Cappetta, H., 1987. Chondrichthyes II: Mesozoic and Cenozoic Elasmobranchii. Handbook of Paleoichthyology, 3B. Gustav Fischer Verlag, Stuttgart and New York, 193 pp.
    Cappetta, H. (2006). Elasmobranchii post-Triadici (index generum et specierum). In: Riegraf, W. (Ed) Fossilium Catalogus I:Animalia 142. Leiden, Backhuys Publish, 472pp.
    Cappetta, H & Nolf, D, 2005. Revision de quelques Odontaspidae (Neoselachii: Lamniformes) du Paleocene et de l'Eocene du Bassin de la mer du Nord Bulletin de l'institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre 75:237-266.
    Case, G., 1981. Late Eocene selachians from South-Central Georgia. Palaeontographica Abt. A, 176: 52-79.
    Case, G., 1994. Fossil Fish Remains fron the Late Paleocene Tuscahoma and Early Eocene Bashi Formations of Meridian, Lauderdale County, Mississippi. Palaeontographica Abt. A, 230: 97-138.
    Case, G. & Leggett, J., 1999. Cretolamna cf C. aschersoni (Stromer) (Neoselachii: Cretoxyrhinidae), from the Late Paleocene/Early Eocene of Mississippi, USA, with Comparisons to Moroccan Fauna. The Mosasaur 6:25-28.
    Kent, B. 1994. Fossil Sharks of the Chesapeake Region. Egan Rees & Boyer, Maryland, 146 pp.
    Landemaine, O., 1991. Sélaciens nouveaux du crétacé supérieur du sud-ouest de la France quelques apports a la systematique des elasmobranches. Société Amicale des Géologues Amateurs, Muséum National d'Histoire Naturelle, Paris, no. 1, 45pp.
    Stromer, E., 1905 Die Fischreste des mittleren ubd oberen Eocäns von Ägypten, I. Die selachier, B. Squaloidei. Beitrag Paleontologische und Geologische Osterreich-Ungarns 18: 163-92.
    Stromer, E., 1910 Reptilien- und Fischreste aus dem marinen Altertiär von Südtogo (Westafrika). Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, LXII: 478-507, 1 plate, 4 text-figs.
    White, E., 1926. Eocene Fishes from Nigeria Bulletin - Geological Survey of Nigeria, 10. pp 1-82.
    Welton, B. J. and R. F. Farish 1993. The Collector's Guide to Fossil Sharks and Rays from the Cretaceous of Texas. Before Time, Texas. 204 pp.

     

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