Category: Dinosaur

Elasmosaurus (El-lazz-mo-sore-us), ‬Ribbon lizard, is the best known and last of the long-necked plesiosaurs. Elasmosaurid plesiosaurs were an important part of Cretaceous marine reptile communities and are generally considered to have been predators of small, agile, free-swimming fish and cephalopods. Professor Bob Bakker has speculated based on skull comparisons that the elasmosaurid plesiosaurs of the Cretaceous were not directly descended from the Jurassic plesiosaurs. Instead he has proposed that they re-evolved from the short-necked pliosaurs.



Genera and Species

Classification: Plesiosauria , Plesiosauroidea, Elasmosauridae

Species: E. platyurus


Elasmosaurus had the largest number of vertebrae in any plesiosaur (72). Plesiosaurs had a design unlike any living animal; it has been described as a turtle “threaded” by a snake. Long, thin teeth that protruded from the mouth intermeshed, to form a fish trap. They gave birth to live young because they could no longer venture on land (Dixon 2006).


LENGTH: 14 m (42 - 45 ft).

WEIGHT: 3 tons.


Elasmosaurus ate fish and squid like belemnites and ammonites, swallowing them whole along with stones called gastroliths to process them. They were slow swimmers that used their long necks to ambush their prey. Plesiosaurs used their paddle-shaped limbs in alternating wing-like movements to fly through the water.

History of Discovery

Discovery, Cope, 1869; it is known from many incomplete fossils. The long neck was not very flexible, and was limited to side-to-side movement (Smith n.d.).


Found in Kansas, North America, and lived in the shallow intercontinental sea.


  1. Knol, R. (2013, March 13). Elasmosaurus. Retrieved May 22, 2014, from http://www.dinosaurcollectorsitea.com/cret_sea_elasmosaurs.html

  2. Dixon, D. (2006). The Complete Book of Dinosaurs (pp. 10-12). London UK: Hermes House.

  3. Smith, A. (n.d.). Elasmosaurus Cope, 1869. . Retrieved May 22, 2014, from http://plesiosauria.com/genera/elasmosaurus/

  4. Elasmosaurus. (n.d.).Retrieved May 22, 2014, from http://www.prehistoric-wildlife.com/species/e/elasmosaurus.html

  5. Pleasiosauria. (2013, June 13). Elasmosaurus.