Fossil range: Late Cretaceous
Platecarpus coryphaeus
Scientific classification








  • P. planifrons
  • P. tympaniticus
  • P. bocagei
  • P. coryphaeus

Platecarpus ("Flat wrist") is an extinct genus of aquatic lizard belonging to the mosasaur family, living around 75 million years ago during the end of the Cretaceous period. Fossils have been found in Belgium and the United States.[1]


Sharp williston platecarpus

Platecarpus skeleton.

Platecarpus yale1

Platecarpus skull, Peabody Museum, Yaleo University,

Like other mosasaurs, Platecarpus had a long, laterally flattened tail, steering flippers, and deadly, tooth-lined jaws. It was around 4.3 meters (14 ft) long, with half of that length being taken up by its sinuous tail. It probably swam in a snake-like fashion. Platecarpus probably fed on fish, squid, and ammonites.[1] They were medium sized animals, reaching about 7 meters (23 ft) in length. The platecarpine mosasaurs had evolved into the very specialized plioplatecarpine group by the end of the Cretaceous.


The skull structure of Platecarpus is unique among mosasaurs. This genus is characterized by a short skull, and have the least number of teeth in its jaw than compared to any other mosasaur(approximately 10 teeth in each dentary)[note 1].

Taxonomic HistoryEdit

Platecarpus was probably the most common genus of mosasaur in the Western Interior Sea during the deposition of the Smoky Hill Chalk in Kansas, and Platecarpus ictericus is the most commonly occuring species[2]. There is some controversy regarding the description of the genus Platecarpus since it includes some diverse, and possibly unrelated forms.

Platecarpus 2

Platecarpus velox fossil, Muséum national d'histoire naturelle, Paris

The type specimen of Platecarpus (P. planiforms) was discovered by Professor B. F. Mudge and was classified by Edward Drinker Cope as Clidastes planiformes.[2] In 1898, on further analysis of the remains, it was determined that the mosasaur be placed in a separate genus, Platecarpus.[3] The type specimen underwent another taxonomic review in 1967, when paleontologist Dale Russell determined that the remains were too fragmentary to be placed within any genus, and deemed it to be a specimen of "uncertain taxonomic position".[4] A 2006 discovery in the Smoky Hill Chalk of Kansas re-affirmed this position with the discovery a complete fossilized skull being unearthed.[5]


Platecarpus Coryphaeus

Platecarpus coryphaeus at Royal Ontario Museum.


Skeleton of Platecarpus planifrons

Various skeletons of this mosasaur have been found in Cretaceous deposits in Kansas, however, only one complete skull has ever been recovered.[2]Platecarpus fossils have been found in rocks that date back to the late Coniacian through the early Campanian in the Smoky Hill Chalk.


Compared to the tylosaurs, plioplatecarpine mosasaurs had much less robust teeth, suggesting that they fed on smaller (or softer) prey such as small fish and squid[2].


  1. ^ Burnham (1991) recently reported an unclassified species of Plioplatecarpus from the Lower Demopolis Formation in Alabama that has a lower number of teeth in its jaws.


  1. ^ a b EoDP>Palmer, D., ed (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 87. ISBN 1-84028-152-9.
  2. ^ a b c d Everhart, Michael J.. Oceans of Kansas: A Natural History of the Western Interior Seaway. c. 2005. pp. 165-169
  3. ^ Williston (1898a)
  4. ^ Russell (1967)
  5. ^ (Everhart and Johnson, 2001)

Further ReadingEdit

Williston 1898 - includes drawings of the skull of Platecarpus ictericus