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. phosphaticus, G.
schurmanni, G. simplex.
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. Iaroch�ne, 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.
- Stomach contents of Globidens, a shell-crushing mosasaur (Squamata),
from the Late Cretaceous Pierre Shale Group, Big Bend area of the
Missouri River, central South Dakota. - Geological Society of America
Special Papers, 427:167-176. -
- The North African Mosasaur Globidens phosphaticus
from the
Maastrichtian of Angola. - Historical Biology. 22 (1–3): 175–185. -
Michael J. Polcun, Louis L. Jacobs, Anne S. Schulp & Oct�vio
Mateus - 2010. J. E. Martin & J. E. Fox - 2007.
- Globidens(?) timorensis E.
VON HUENE, 1935: not a durophagous
mosasaur, but an enigmatic Triassic ichthyosaur. - Neues Jahrbuch f�r
Geologie und Pal�ontologie - Abhandlungen. 293 (1): 107–116. - Eric
W.A. Mulder & John W.M. Jagt - 2019.
- Insights into the anatomy and functional morphology of durophagous
mosasaurines (Squamata: Mosasauridae) from a new species of Globidens
from Morocco. - Zoological Journal of the Linnean Society. - Aaron
LeBlanc, Sydney Mohr & Michael Caldwell - 2019.