C. maximus (GUNNERUS, 1765), Extant Basking Shark

This huge shark, (to 10 with reports to 15 meters) is second only to the whale shark in size. It is characterized by its large mouth with numerous (200 files per jaw) small, similarly shaped, hook-like teeth and extremely enlarged gill openings, which incorporate unique gill rakers. These plankton-capturing devices are hair-like (mucous) denticles, which are periodically shed and when found, help confirm the presence of this genus in the fossil record. C. maximus is a migratory species of temperate & boreal, coastal & off-shore waters.

Fossil Basking Sharks

Leriche 1908 erected the only fossil basking shark taxon (Cetorhinus parvus) based solely on small Cetorhinus-like gill rakers from the Oligocene of Belgium. Herman (1979) attributed small (<2mm) teeth, reminiscent of Alopias exigua (PROBST 1879), found in the same sediments as these gill rakers to C. parvus. The roots of these teeth were unlike the extant basking shark as reflected by their often broader roots (less homogeneous) and lack of a nutrient groove. This tooth-design is known from the Oligo-Miocene of Belgium & Germany.

  • Jordan & Hannibal (1923) reported as Gyrace occidentalis (AGASSIZ, 1856), Cetorhinus maximus-like teeth from the middle Miocene of California.
  • Cappeta (1987:107) noted various Oligo-Pliocene European occurrences of the genus and based on communications with Welton, the possible occurrence in the Eocene of North America.
  • Cione & Reguero (1998) reported a Cetorhinus gill raker from the La Meseta Formation (Middle Eocene) of Seymour Island (Antarctica). In this paper, they summarized the various reports of this taxon from the fossil record: Eocene - North America (dubious), Oligocene - Europe, Miocene - Europe, No. America & Japan and Pliocene of Europe & Chile.
  • Heim & Bourdon (elasmo.com, 1998) included a Cetorhinus gill raker and a C. maximus-like tooth in the Lee Creek fauna from the Pungo River Formation..
  • Müller 1999: 43, pl 1 fig 14-15 reported as C. parvus, basking shark gill rakers from the Old Church Fm. (Oligocene) of Virginia
  • Purdy et al. (2001: 109) reported as Cetorhinus sp, a single C. maximus-like tooth (Pungo River unit 3, Lower Miocene) and a clasper spine (referring to Leriche 1926, fig. 195, pl 37: figs. 6,7).
  • Reinecke et al (2001 & 2005) provided an excellent series of C. parvus tooth images from the Oligocene of Germany.
  • Cappetta (2006), referring to it as an Early Pliocene taxon known from gill rakers, synonymized C. parvus with C. maximus.
  • Hovestadt et al. (2010) included basking shark gill rakers from the Rupelian (E. Oligocene) of Germany as C. parvus.
  • Boessenecker (2011) attributed teeth and gill rakers from the Purisima Formation (Mio-Pliocene) of central California to C. maximus. The author noted that based on the variability of these teeth as reported by Shimada (2002), the usage of C. parvus might need to be reanalyzed.

    Below are illustrated Cetorhinus teeth and gill rakers.The teeth are from Sharktooth Hill (Kern County, California) and conform well with Cappetta's illustration and description of a C. maximus tooth. The roots are robust but worn, weakly revealing the presence of two lobes. Cappetta suggests that the nutrient groove is narrow and significantly deeper in unworn teeth. A cutting edge is present, does not extend to the apex of the crown and is irregular near the root where the cusp appears "pinched".

    REFERENCES

    Boessenecker, R. W., 2011. A new marine vertebrate assemblage from the Late Neogene Purisima Formation in central California, Part I: fossil sharks, bony fish, birds, and implications for the age of the Purisima Formation west of the San Gregorio fault. PalArch’s Journal of Vertebrate Palaeontology, 8(4).
    Cappetta, H., 1987. Handbook of Paleoichthyology. Chondrichthyes II: Mesozoic and Cenozoic Elasmobranchii. Gustav Fischer Verlag, Stuttgart and New York, 193 pages.
    Cappetta, H., 2006. Elasmobranchii post-Triadici (index generum et specierum). In: Riegraf, W. (Ed) Fossilium Catalogus I:Animalia 142. Leiden, Backhuys Publish, 472pp.
    Cione, A. and Reguero, M., 1998. A Middle Eocene basking shark (Lamniformes, Cetorhinidae) from Antarctica. Antarctic Science 10(1): 83-88.
    Herman, J., 1979. Réflexions sur la systématique des Galeoidei et sur les affinités du genre Cetorhinus à l'occasion de la découverte d'éléments de la denture d'un exemplaire fossile dans les sables du Kattendijk à Kallo (Pliocène Inférieur, Belgique). Annales de la Société Géologique de Belgique, 102: 357-377.
    Hovestadt, D.C., M. Hovestadt-Euler & N. Micklich, (2010). A review of the chondrichthyan fauna of Grube Unterfeld (Frauenweiler) clay pit. Kaupia, Darmstädter Beiträge zur Naturgeschichte, 17: 57-71.
    Jordan, D. and Hannibal, H., 1923. Fossil sharks and rays of the Pacific slope of North America. Bull. So. California Acad. Sci., 22:27-68.
    Leriche, M., 1908. Sur un appareil fanonculaire de Cetorhinus trouvé à l'état fossile dans le Pliocène d'Anvers. Comptes rendus hebdomaires des séances de l'Academie des Sciences de Paris. 146: 875-878.
    Leriche, M., 1926. Les Poissons tertiaires de la Belgique. (IV. Les Poissons Néogènes). Mémoires du Musée Royal d'Histoire Naturelle de Belgique, 32: 365-472.
    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.
    Reinecke, T., Stapf, H and Raisch, M., 2001. Die selachier und chimären des Unteren Meeressandes und Schleichsandes im Mainzer Becken (Rupelium, Unteres Oligozän). Palaeontos 1, Antwerp. 73pp 63 plates.
    Reinecke, T., Moths, H., Grant, A. and Breitkreutz, H., 2005. Die Elasmobranchier des Norddeutschen Chattiums, Insbesondere des Sternberger gesteins (Eochattium, Oberes Oligozän). Palaeontos 8, Antwerp.134pp 60 plates.
    Shimada, K. 2002. Dentition of the modern basking shark, Cetorhinus maximus (Lamniformes: Cetorhinidae), and its paleontological and evolutionary implications. Journal of Fossil Research 35: 1-5.

     

    		•