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Name means: Ribbon Lizard


Species: platyurus

Range: Late Cretaceous (Santonian-Campanian, 94-71 MYA) from Wyoming, Kansas, and possibly Alaska, Sweden, Japan

Size estimate: 40-45 ft length, 5-10 tons

Discovery: Edward Drinker Cope, 1868

Classification: reptilia, sauropterygia, plesiosauria, xenopsaria, elasmosauridae

Dinosaurs may never have adapted to life under the ocean. Other reptile groups, however, took to the sea as completely as whales. One group called the plesiosaurs swam the oceans of the Mesozoic era like giant reptilian seals. Elasmosaurus represents this group here at the park. Its distinctive neck contains 72 bones—ten times more than any mammal.  Such a high number of bones made it quite flexible, but the shape of the neck bones limited how far it could bend. For example, it could not bend its neck in an S-shape like a swan. Elasmosaurus' neck and head let it sneak up on schools of fish without scaring them with its large body.


Scientists remain divided on how Elasmosaurus swam. Evidence in the animal's shoulder bones imply it used its front flippers to swim like a penguin. Trackways preserved in shallow water suggest plesiosaurs swam with all four limbs. Perhaps it varied its technique in different areas. Speed estimates also vary, though many scientists agree that Elasmosaurus did not specialize in fast movement. It could sustain a high level of activity though, like modern seals or fast-moving fish like Swordfish. Oddly enough, the chemical makeup of its teeth proves it could control its body temperature. The lungs of distantly related seagoing reptiles called mosasaurs resembled whales', and Elasmosaurus might have shared that lung design.


Elasmosaurus played a role in the history of paleontology as well. When E.D. Cope first described Elasmosaurus, he placed the head on its tail by mistake. He thought the long neck was really a tail used to push the animal through the water like the mosasaur Tylosaurus. According to legend, when his rival O.C. Marsh criticized his reconstruction, the wealthy and embarrassed Cope bought every copy of the journal that published it. This fiasco made the two scientists bitter enemies, and led to a decades-long rivalry dubbed "The Bone Wars." Many of the animals in the park owe their names to these two trying to one-up each other.

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