The group of marine reptiles called plesiosaurs were first uncovered from the rocks of Southern England, in the Oxford and Kimmeridge Clay Formations of the Jurassic, but have now been found pretty much throughout the world and from every part of the Mesozoic Era. First identified as “snakes threaded through turtle bodies”, we now know that this iconic design was not as homogenous as first imagined. The plesiosaurs were a very successful group, with their beginnings in the Triassic around 230 million years ago. Their time ended when the Mesozoic came to a crashing halt around 66 million years ago. But certain people maintain that they inhabit inland lakes today, even if said lakes have no connection to the ocean.
The plesiosaurs themselves were among the largest and most successful marine reptiles of all time, only surpassed by a few giant ichthyosaurs. There were those that were whale-like and dealt death with a pair of massive, bone-crushing jaws. These giants dominated the seas of the Jurassic, going extinct halfway through the Cretaceous. Then there were long-necked generalists and speedy dolphin-like pursuit predators. Most of these long-necked animals have been described as fish-trappers with their interlocking teeth and the wide gape of their jaws, even if they were not able to curve their necks out of the water like a classical marine monster.
Now though, a plesiosaur from the Late Cretaceous of Seymour Island, Antarctica is proving that some had incredible specializations and were certainly not run-of-the-mill members of their group. The animal in question is an elasmosaur, one of the plesiosaurs with the famously long, serpentine necks, and is called Morturneria. Morturneria is actually one of a small number of these animals from the Southern Hemisphere, and was not as long-necked as its distant cousins. Morturneria was not one the great snake-necked giants of its family, being of moderately large size for a plesiosaur at around 8 meters.