Dec. 8, 2006 — Millions of years ago, a young plesiosaur died and sunk to the bottom of what is now the Southern Ocean. Recently, paleontologists found the well-preserved skeleton of this unfortunate juvenile in Antarctica, according to researchers who have been preparing the specimen for public exhibit.
Plesiosaurs were giant sea reptiles that lived 210 to 65 million years ago during the dinosaur era. Remains of juveniles are quite rare.
Michelle Pinsdorf, who has been working on the skeleton, told Discovery News that the plesiosaur is only missing some of its paddle-like flippers, part of the end of its tail and its skull.
"Skulls are more delicate and lightweight and are not that strongly attached to the body," Pinsdorf, a researcher and graduate student at the South Dakota School of Mines & Technology, told Discovery News. "The same is true for the human head. As a result, we find very few ancient skeletons with the skulls still attached."
A pinkish residue — probably composed of minerals — is visible between some bone gaps, which would have been filled with cartilage during the plesiosaur's lifetime.
One of the most notable features of the ancient sea reptile's remains is its gastralian basket, a set of thin, rib-like bones that are stacked up along the center of the belly region. Often these bones crack or dislodge over time, but they are very well-preserved in this skeleton, according to Pinsdorf.
Even its stomach stones also survived.
"These are stones that the animal could have used to aid digestion, such as crushing up food, or perhaps for ballast in helping to maintain balance when it was under water," Pinsdorf explained.
Pinsdorf is working with lead researcher James Martin, who found the specimen during a recent expedition to the harsh and frigid continent, funded by the National Science Foundation.
Antarctica may be cold now, but during the plesiosaur's lifetime, Antarctica would have been much farther north, closer to Australia, to which it was once attached. Antarctica was also connected to South America.
Despite the continental connections, University of Alberta paleontologist Philip Currie, who recently returned from Antarctica, told Discovery News that certain geological and climatic barriers caused many prehistoric Antarctic animals, such as dinosaurs, to evolve in relative isolation.
A six- to eight-foot-tall carnivorous theropod and a 30-foot-long sauropod recently were discovered thousands of miles apart in Antarctica.
