Platecarpus: Difference between revisions

Platecarpus; Temporal range: Late Cretaceous
	Platecarpus coryphaeus.
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Order:	Squamata
Suborder:	Scleroglossa
Family:	Mosasauridae
Subfamily:	Plioplatecarpinae
Genus:	Platecarpus; Cope, 1869
Species
	P. planifrons Cope, 1874 (Originally Clidastes planiforms; P. tympaniticus Cope, 1869 (includes P. ictericus and P. coryphaeus); P. bocagei; P. coryphaeus;

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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]

Description

Platecarpus skeleton.

Like other mosasaurs, Platecarpus had a long, laterally flattened tail, steering flippers, and deadly, tooth-lined jaws. It was around 4.3 metres (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 metres (23 ft) in length^{[citation needed]}. The platecarpine mosasaurs had evolved into the very specialized plioplatecarpine group by the end of the Cretaceous. An exceptionally well-preserved specimen of Platecarpus held in the Natural History Museum of Los Angeles County shows skin impressions, pigments around the nostrils, bronchial tubes and the presence of a high profile tail fluke, showing that mosasaurs did not necessarily have an eel-like swimming method but were faster, more powerful swimmers.^[2]

Skull

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 History

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 occurring species^[3]. There is some controversy regarding the description of the genus Platecarpus since it includes some diverse, and possibly unrelated forms.

File:Platecarpus.jpg

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.^[3] In 1898, on further analysis of the remains, it was determined that the mosasaur be placed in a separate genus, Platecarpus.^[4] 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".^[5] A 2006 discovery in the Smoky Hill Chalk of Kansas re-affirmed this position with the discovery a complete fossilized skull being unearthed.^[6]

Fossils

Various skeletons of this mosasaur have been found in Cretaceous deposits in Kansas, however, only one complete skull has ever been recovered.^[3] Platecarpus fossils have been found in rocks that date back to the late Coniacian through the early Campanian in the Smoky Hill Chalk.

Diet

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^[3].

Notes

^ 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.

References

^ ^a ^b Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 87. ISBN 1-84028-152-9.
^ Lindgren, J., Caldwell, M.W., Konishi, T. & Chiappe, L.M. 2010. Convergent evolution in aquatic tetrapods: insights from an exceptional fossil mosasaur. PLoS One 5 (8) e11998: 1-10
^ ^a ^b ^c ^d Everhart, Michael J.. Oceans of Kansas: A Natural History of the Western Interior Seaway. c. 2005. pp. 165-169
^ Williston (1898a)
^ Russell (1967)
^ (Everhart and Johnson, 2001)

@@ Line 27: / Line 27: @@
 [[Image:Sharp williston platecarpus.jpg|thumb|left|''Platecarpus'' skeleton.]]
 [[Image:Platecarpus yale1.JPG|thumb|left|''Platecarpus'' skull, Peabody Museum, Yaleo University,]]
-Like other mosasaurs, ''Platecarpus'' had a long, laterally flattened tail, steering flippers, and deadly, [[tooth]]-lined [[jaw]]s. It was around {{convert|4.3|m|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 [[ammonite]]s.<ref name=EoDP>{{cite book |editor=Palmer, D.|year=1999 |title= The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals|publisher= Marshall Editions|location=London|page= 87|isbn= 1-84028-152-9}}</ref> They were medium sized animals, reaching about {{convert|7|m|ft}} in length{{fact|date=March 2009}}. The platecarpine mosasaurs had evolved into the very specialized plioplatecarpine group by the end of the [[Cretaceous]].
+Like other mosasaurs, ''Platecarpus'' had a long, laterally flattened tail, steering flippers, and deadly, [[tooth]]-lined [[jaw]]s. It was around {{convert|4.3|m|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 [[ammonite]]s.<ref name=EoDP>{{cite book |editor=Palmer, D.|year=1999 |title= The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals|publisher= Marshall Editions|location=London|page= 87|isbn= 1-84028-152-9}}</ref> They were medium sized animals, reaching about {{convert|7|m|ft}} in length{{fact|date=March 2009}}. The platecarpine mosasaurs had evolved into the very specialized plioplatecarpine group by the end of the [[Cretaceous]]. An exceptionally well-preserved specimen of ''Platecarpus'' held in the [[Natural History Museum of Los Angeles County]] shows skin impressions, pigments around the nostrils, bronchial tubes and the presence of a high profile tail fluke, showing that mosasaurs did not necessarily have an eel-like swimming method but were  faster, more powerful swimmers.<ref>Lindgren, J., Caldwell, M.W., Konishi, T. & Chiappe, L.M. 2010. Convergent evolution in aquatic tetrapods: insights from an exceptional fossil mosasaur. PLoS One 5 (8) e11998: 1-10</ref>
 ===Skull===