Elasmosaurus sp by ashere-d5i4md1

Common Name Plesiosaur
Group Reptiles
Species Elasmosaurus remuspissa
Time Late Cretaceous
Diet Carnivore
Temperament Docile
XP For Kill 15 XP
Favorite Kibble Kibble (Rex Egg)
Tameable Yes
Rideable Yes
Saddle Plesiosaur Saddle (lvl 60)
Platform Saddle Plesiosaur Platform Saddle (lvl 80)

Elasmosaurus Remuspissa has a strange role in the oceanic food chain. It almost exclusively hunts the smaller creatures in the waters, leaving most even moderately large creatures (such as humans) alone. The sheer size of the Elasmosaurus means that the quantity of creatures it must eat to sustain itself is nothing short of enormous.

Despite its imposing size, Elasmosaurus still has natural predators. Well, a natural predator: the Megalodon. Apart from that monstrous creature, I myself have only ever seen two creatures bring down an Elasmosaurus: a Spinosaurus that found its way into the deeps (not common), and humans. Though I will admit, I have yet to fully explore the staggering deep underwater caverns surrounding the island.


Much like the Brontosaurus on land, Elasmosaurus is an excellent way to transport large quantities of goods over water. These powerful creatures are in fact so large that they can be used as mobile water bases. Ambitious tribes sometimes build bunkers right onto the backs of Elasmosaurus instead of building cargo ships.

— The Dossier

The Elasmosaurus, more commonly known as the Plesiosaurus or Plesiosaur, is a large carnivorous reptile found in the deepest depths of the oceans of the Ark.

Wikipedia has a more detailed and comprehensive article on Plesiosaur


The Plesiosaur has an almost teardrop-shaped body. Its size, long neck, and four whale-like flippers make it unmistakable for any other creature. The neck itself makes up half of the creature's length, and the mouth is lined with many sharp teeth. Commonly found in pairs, this large marine reptile hunts in the island's deeper waters for fish and squid, working as a team to corral their prey. Despite their size and often camouflaged coloration, plesiosaurs are sometimes preyed upon by other large marine predators and, occasionally, adventurous Spinosaurus heading out from the coast.


Plesiosaurs swim around in groups of two or three, in the depths of the ocean, never surfacing. When players get too close, they start to attack and will follow them for a short distance; they seem to lose interest quickly, especially when swimming vertically.


Much like the Brontosaurus on land, Plesiosaur is an excellent way to transport large quantities of goods over water. These powerful creatures are in fact so large that they can be used as mobile water bases. Ambitious tribes sometimes build bunkers right onto the backs of Plesiosaur instead of building cargo ships.




In or near underwater cave entrances.


  • The dossier for Elasmosaurus actually mentions the underwater caves found in the game. This also seems to indicate that there are even more fearsome creatures in the depths of the caverns.
  • The Elasmosaurus in-game is about 175 feet long, far exceeding it's maximum real-world length of 46 feet.
  • Due to its enormous size the taming time is extremely long in which it is susceptible to enemies like Megalodons. They might also lower the effectiveness due to possible inflicted damage.
  • Plesiosaurs are pretty rare to find but there are usually two of them next to the underwater cave entrance located at 83.0/09.9 (see map on the right).
  • Plesiosaurs always drop Firework Flare Gun Skin when killed.
  • Plesiosaurs are found near the entrance to underwater caves, in numbers varying from about 1 - 4.
  • Despite the dossier stating it leaves most creatures the size of humans and larger alone, it is common for them to attack megaladons and other creatures on sight.
  • Before the introduction of the crossbow, plesiosaurs were usually kited into an underwater cave so that they could be tranqed.
  • The Dossier says that the Megalodon is the only predator of the Plesiosaur, though the latter is mostly stronger.
  • Quite disturbingly the Dossier states that "Have yet to explore ... The underwater caves" directly after talking about predators of the Plesiosaur. This could hint at a new underwater boss or monster of the deep. A similar hint is dropped on the Ichthyosaur's dossier in the form of a giant underwater monster behind it in a size comparison.

Trivia not relevant for the game

  • The name 'Plesiosaur' refers to a large group of animals that ruled the seas from the Jurassic up to the end of the Age of Reptiles. Genus Elasmosaurus thrived in the shallow seas that covered the central United States during the Late Cretaceous period.
Cope Elasmosaurus

The "head-on-the-wrong-end" version of Elasmosaurus platyurus. Cope did not include the "hind" (actually front) paddles in this figure in part due to his erroneous belief that Elasmosaurus was propelled by its extremely long “tail” (neck).


An outdated historical depiction of Dryptosaurus confronting Elasmosaurus, with two Hadrosaurus in the background. By Edward Drinker Cope, 1869.

  • Elasmosaurus platyurus was described in March, 1868 by Edward Drinker Cope from a fossil discovered and collected by Dr. Theophilus Turner, a military doctor, in western Kansas, United States. Although other specimens of elasmosaurs have been found in various locations in North America, Carpenter (1999) determined that Elasmosaurus platyurus was the only representative of the genus. When E. D. Cope got the specimen in early March, 1868, he had a biased idea of what it should look like, and mistakenly placed the head on the wrong end (i.e. the tail). In his defense, at the time he was an expert on lizards, which have a short neck and a long tail, and no one had seen a plesiosaur the size of Elasmosaurus. While folk legend notes that it was Othniel Charles Marsh who pointed out the error, there is no factual evidence for this account, but, this event is may have caused their long and hate-filled feud, known as the Bone Wars. In fact, although Marsh personally gathered at least one plesiosaur from Kansas, and had several more from Kansas in the Yale Peabody collection, he did not write any paper on them. Although Cope announced the discovery of Elasmosaurus platyurus in March 1868, he did not print the "preprint" of his wrong reconstruction of Elasmosaurus until August 1869. While much smaller, long-necked plesiosaurs from the Jurassic of England were well known at the time, but Elasmosaurus was the first known Cretaceous elasmosaur. Cope's reconstruction showed it to have a long curving tail like a lizard or a mosasaur. Note that while O.C. Marsh claimed to have pointed out Cope's error "20 years after the fact" in an 1890 newspaper article, it was in fact Joseph Leidy who pointed out the problem in his Remarks on Elasmosaurus platyurus speech at the Academy of Natural Sciences of Philadelphia meeting on March 8, 1870.


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