10 Facts About Elasmosaurus, Ancient Marine Reptile

One of the first identified marine reptiles, and an instigator of the 19th-century fossil hunt known as the Bone Wars, Elasmosaurus was a long-necked predator. The plesiosaur lived in North America during the Late Cretaceous period.

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Elasmosaurus Was One of the Largest Plesiosaurs That Ever Lived


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Plesiosaurs were a family of marine reptiles that originated in the late Triassic period and persisted (in increasingly dwindling numbers) all the way up to the K/T Extinction. At close to 50 feet long, Elasmosaurus was one of the biggest plesiosaurs of the Mesozoic Era, though still not a match for the largest representatives of other marine reptile families (the ichthyosaurs, pliosaurs, and mosasaurs), some of which could weigh up to 50 tons.

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The First Fossil of Elasmosaurus Was Discovered in Kansas

Wikimedia Commons

Shortly after the end of the Civil War, a military doctor in western Kansas discovered a fossil of Elasmosaurus—which he quickly forwarded to the eminent American paleontologist Edward Drinker Cope, who named this plesiosaur in 1868. If you're wondering how a marine reptile ended up in landlocked Kansas, of all places, remember that the American West was covered by a shallow body of water, the Western Interior Sea, during the Late Cretaceous period.

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Elasmosaurus Was One of the Instigators of the Bone Wars

During the late 19th century, American paleontology was riven by the Bone Wars—the decades-long feud between Edward Drinker Cope (the man who named Elasmosaurus) and his arch-rival, Othniel C. Marsh of Yale University. When Cope reconstructed the skeleton of Elasmosaurus, in 1869, he briefly placed the head on the wrong end, and legend has it that Marsh loudly and undiplomatically pointed out his mistake—though it seems that the responsible party may really have been paleontologist Joseph Leidy.

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The Neck of Elasmosaurus Contained 71 Vertebrae

Plesiosaurs were distinguished by their long, narrow necks, small heads, and streamlined torsos. Elasmosaurus had the longest neck of any plesiosaur yet identified, about half the length of its entire body and supported by a whopping 71 vertebrae (no other plesiosaur had more than 60 vertebrae). Elasmosaurus must have looked almost as comical as an even longer-necked reptile that preceded it by millions of years, Tanystropheus.

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Elasmosaurus Was Incapable of Raising Its Neck Above the Water

Given the enormous size and weight of its neck, paleontologists have concluded that Elasmosaurus was incapable of holding anything more than its tiny head above the water—unless, of course, it happened to be sitting in a shallow pond, in which case it could hold its majestic neck out to its full length.

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Like Other Marine Reptiles, Elasmosaurus Had to Breathe Air

One thing people often forget about Elasmosaurus, and other marine reptiles, is that these creatures had to surface occasionally for air. They weren't equipped with gills, like fish and sharks, and couldn't live below water 24 hours a day. The question then becomes, of course, exactly how often Elasmosaurus had to surface for oxygen. We don't know for sure, but given its huge lungs, it isn't inconceivable that a single gulp of air could fuel this marine reptile for 10 to 20 minutes.

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Elasmosaurus Probably Gave Birth to Live Young

It's very rare to witness modern marine mammals giving birth to their young, so imagine how difficult it is to determine the birthing style of an 80-million-year-old marine reptile. While we don't have any direct evidence that Elasmosaurus was viviparous, we do know that another, closely related plesiosaur, Polycotylus, gave birth to live young. Most likely, Elasmosaurus newborns would emerge from their mother's womb rear-first, to give them extra time to acclimate to their undersea environment.

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There Is Only One Accepted Elasmosaurus Species

Like many prehistoric reptiles discovered in the 19th century, Elasmosaurus gradually accumulated an assortment of species, becoming a "wastebasket taxon" for any plesiosaur that even remotely resembled it. Today, the only remaining Elasmosaurus species is E. platyurus; the others have since been downgraded, synonymized with the type species, or promoted to their own genera (as happened with Hydralmosaurus, Libonectes and Styxosaurus).

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Elasmosaurus Has Given Its Name to an Entire Family of Marine Reptiles

James Kuether

Plesiosaurs are divided into various sub-families, among which one of the most populous is the Elasmosauridae—marine reptiles characterized by their longer-than-usual necks and slim bodies. While Elasmosaurus is still the most famous member of this family, which ranged across the seas of the later Mesozoic Era, other genera include Mauisaurus, Hydrotherosaurus, and Terminonatator.

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Some People Believe the Loch Ness Monster Is an Elasmosaurus

loch ness monster
Wikimedia Commons

Judging by all those hoax photographs, you could make a case that the Loch Ness Monster looks a lot like Elasmosaurus (even if you disregard the fact that this marine reptile was incapable of holding its neck out of the water). Some cryptozoologists insist, without a shred of reliable evidence, that a population of Elasmosaurs has managed to survive in the northern reaches of Scotland.

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Strauss, Bob. "10 Facts About Elasmosaurus, Ancient Marine Reptile." ThoughtCo, Feb. 16, 2021, thoughtco.com/facts-about-elasmosaurus-1093328. Strauss, Bob. (2021, February 16). 10 Facts About Elasmosaurus, Ancient Marine Reptile. Retrieved from https://www.thoughtco.com/facts-about-elasmosaurus-1093328 Strauss, Bob. "10 Facts About Elasmosaurus, Ancient Marine Reptile." ThoughtCo. https://www.thoughtco.com/facts-about-elasmosaurus-1093328 (accessed March 22, 2023).