Globidens


This illustration is available as a printable colouring sheet. Just click here and right click on the image that opens in a new window and save to your computer.

Name: Globidens ‭(‬Globe teeth‭)‬.
Phonetic: Glo-bih-denz.
Named By: Gilmore‭ ‬-‭ ‬1912.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Squamata,‭ ‬Scleroglossa,‭ ‬Mosasauridae,‭ ‬Mosasaurinae,‭ ‬Globidensini.
Species: G.‭ ‬alabamaensis‭ (‬type‭)‬,‭ ‬G.‭ ‬dakotensis,‭ ‬G.‭ ‬timorensis,‭ ‬G.‭ ‬schurmanni.
Diet: Carnivore.
Size: 6‭ ‬meters long.
Known locations: USA.‭ ‬Africa.
Time period: Campanian to Maastrichtian of the Cretaceous.
Fossil representation: ‭M‬any specimens.

       Although Globidens was not the only mosasaur to adapt to a diet of almost exclusively hard shelled animals,‭ ‬it does display perhaps the most specialised teeth.‭ ‬Rather than the sharp conical teeth seen in other mosasaurs such as Tylosaurus and Taniwhasaurus,‭ ‬Globidens had rounded teeth that had a‭ '‬globe shaped‭'‬ upper portion of the crown that sat upon a slightly narrower base.‭ ‬An important aspect of the teeth being semispherical rather than conical is that they were much more resilient to impact damage such as chips and cracks.‭ ‬This meant that every time the jaw was moved up and down,‭ ‬each tooth would strike the shell of the prey animal like a ball hammer,‭ ‬cracking up the shell so that Globidens could get at the soft flesh within.‭

       Fossil evidence from Prognathodon,‭ ‬a mosasaur with a seemingly similar prey preference proves that turtles and ammonites were readily available as prey.‭ ‬The teeth and strong jaw of Globidens would have allowed it to tackle potentially tougher and more heavily armoured prey than even the larger Prognathodon could handle.‭
       The exact reason why Globidens and other mosasaurs focused more upon shelled animals remains uncertain.‭ ‬It could have been that traditional food sources began to decline resulting in mosasaurs diversifying to reduce the stress of competition between each other for exactly the same food sources.‭ ‬It may of course have been something simpler such as filling an ecological void to take advantage of another food source.‭ ‬Whatever the precise reason,‭ ‬it was a successful adaptation with mosasaurs like Globidens and Prognathodon having broad geological ranges,‭ ‬and a reign that was only cut short by the Cretaceous-Palaeogene extinction.
       One former species of Globidens, G. aegyptiacus has now been re-described as a distinct genus called Igdamanosaurus.

Further reading
- A new mosasauroid reptile from the Cretaceous of Alabama. - Proceedings of the United States National Museum 41(1870):479-484. - C. W. Gilmore - 1912.
- A new species of Globidens from South Dakota, and a review of the globidentine mosasaurs. - Fieldiana Geology 33(13):235-256. - D. A. Russel - 1975.
- Durophagous Mosasauridae (Squamata) from the Upper Cretaceous phosphates of Morocco, with description of a new species of Globidens. - Netherlands Journal of Geosciences - Geologie en Mijnbouw 84(3):167-175. - N. Bardet, X. Pereda Suberbiola, M. Iarochène, M. Amalik & B. Bouya - 2005.
- A new species of the durophagous mosasaur Globidens (Squamata: Mosasauridae) from the Late Cretaceous Pierre Shale Group of central South Dakota, USA. - Geological Society of America Special Paper 427:177-198. - J. E. Martin - 2007.



----------------------------------------------------------------------------

Random favourites