Recent orectolobiforms (carpetsharks) span a huge range of sizes, from the mammoth whale shark, large nurse sharks or small bamboo sharks. The smaller taxa are generally associated with the western South Pacific are often inhabit shallow water and feed on small fishes, crustaceans and other invertebrates. Although little is known about Orectoloboides, they could likely be viewed as from one of the smaller orectolobiform families. Based on reported fossil teeth, the dentition was likely clutching/crushing in design with gradational monognathic heterodonty. Until this year (2010) the genus had only been reported from Cretaceous of Europe and North Africa.

Dalinkevicius (1935) erected Ginglymostoma parvula for small teeth from the Lower Cretaceous (Albian), Lithuania which he deemed to be nurse shark. Cappetta (1977), using this material as the type, erected a new genus -- Orectoloboides. Material from Egypt, Spain and Brittan was subsequently included in this genus. Underwood and Cumbaa (2010) were the first to report the taxon from North America when they described Orectoloboides angulatus from the Cenomanian of, Saskatchewan. Bourdon & Everhart (2010) subsequently reported the genus from the Dakota Fm. (Middle Cenomanian) of Kansas as Orectoloboides sp.

Characteristics of the tooth design include:

  • Small but robust teeth (found by bulk processing for micro-elements);
  • Crown with narrow cusp, cuspidate shoulders, long narrow labial apron, and transverse cutting edge;
  • Low, v-shaped root that may be hemiaulacorhizous (closed) or holaulacorhizous (open nutrient groove); and
  • One or more margino-lingual foramina.

    Footnotes

    1This order is often attributed to Applegate, 1972 or Compagno, 1973. Applegate's paper, although apparently written earlier, wasn't published until 1974; ICZN rules would therefore give priority to Compagno.

    Selected References

    Bourdon, J. and Everhart, M.J. 2010. Occurrence of the extinct Carpet shark, Orectoloboides, in the Dakota Formation (Late Cretaceous; Middle Cenomanian) of Kansas. Kansas Academy of Science, Transactions 113(3-4):237-242.(PDF 265kb)
    Cappetta, H. 1977. Sélaciens nouveaux de l’Albien supérieur de Wissant (Pas-de-Calais). Geobios 10:967-973.
    Compagno, L.J.V. 1973. Interrelationships of living elasmobranchs. Zoological Journal of the Linnean Society 53 (Supplement to 1):15-61.
    Dalinkevicius, J.A. 1935. On the fossil fishes of the Lithuanian Chalk. I. Selachii. Mémoires de la Facultédes Sciences de l’ université de Vytautas le Grand 9:247-305.
    Underwood, C.J. and Cumbaa, S.L. 2010. Chondrichthyans from a Cenomanian (Late Cretaceous) bonebed, Saskatchewan, Canada. Palaeontology 53:903-944.

     

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