Wooster’s Fossils of the Week: Mosasaurid teeth from the Cretaceous of Morocco

PrognathodonTeethKhouribgaCretaceousThese impressive teeth are from the mosasaurid Prognathodon and were found in the Upper Cretaceous phosphorites near Khouribga, Morocco. They are not actually a matching set — I just arranged them to look fearsome.

Prognathodon_lutigini_Dmitry_Bogdanov(Prognathodon lutigi from the Upper Cretaceous of Russia. Reconstruction by Dmitry Gogdanov via Wikipedia.)

Prognathodon (the name means “front-jaw tooth”) was a very large mosasaurid, with some specimens up to 12 meters in length. They were cosmopolitan in extent, being found throughout the world in Campanian to Maastrichtian deposits. They lived in deep waters as shown by some specimens with strengthening bony rings around their eye sockets. They were essentially sea-going lizards, and big ones at that.

Note that the teeth are stout and blunt. They were not adapted for tearing flesh but rather crushing hard-shelled prey they found on the seafloor. One skeleton was found with some stomach contents intact, including a sea turtle, a variety of fishes, and an ammonite. This is not the usual diet of other mosasaurid genera which were nektic (swimming) predators.
Louis_DolloPrognathodon was named in 1889 by the famous Belgian paleontologist Louis Antoine Marie Joseph Dollo (1857-1931). Paleontology and History of Life students will immediately recognize that name because of Dollo’s Law: “evolution is not reversible”. (Or its corollary: extinction is forever!) He started his career as an engineer, graduating at the top of his class in 1877 from the École Centrale de Lille. He worked as a mining engineer and, as luck would have it, quickly discovered an extraordinary mass burial of the dinosaur Iguanodon. Studying this genus and other fossil reptiles became his passion. In 1882 he became an assistant naturalist at the Royal Belgian Institute of Natural Sciences in Brussels. One of his many remarkable contributions was to begin to think of fossils as once living organisms in ecological networks. In this sense he essentially founded paleobiology. In 1912 he received the Murchison Medal from the Geological Society of London. Not too shabby for an engineer.


Buffetaut, E. and Bardet, N. 2012. The mosasaurid (Squamata) Prognathodon in the Maastrichtian (Late Cretaceous) of the Cotentin Peninsula (Normandy, northwestern France). Bulletin de la Societe Geologique de France 183: 111-115.

Schulp, A.S., Polcyn, M.J., Mateus, O.,  Jacobs, L.L., Morais, M.L. and Silva Tavares, T. 2006. New mosasaur material from the Maastrichtian of Angola, with notes on the phylogeny, distribution and palaeoecology of the genus Prognathodon. On Maastricht Mosasaurs 45: 57-67.

About Mark Wilson

Mark Wilson is a Professor of Geology at The College of Wooster. He specializes in invertebrate paleontology, carbonate sedimentology, and stratigraphy. He also is an expert on pseudoscience, especially creationism.
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