The Dinocephalosaurus orientalis fossils were discovered in Guizhou province, southern China.
With 32 separate neck vertebrae, it had an extraordinarily long neck and its flippered limbs and well preserved fish in its stomach region indicated it was very well adapted to an oceanic lifestyle, researchers said.
The reptile was originally identified in 2003, but the discovery of additional, more complete specimens since then has enabled an international team of scientists to depict the creature in full.
Nick Fraser, keeper of natural sciences at National Museums Scotland, was one of those involved.
He said: "This discovery allows us to see this remarkable long-necked animal in full for the very first time.
"It is yet one more example of the weird and wonderful world of the Triassic that continues to baffle palaeontologists.
"We are certain that it will capture imaginations across the globe due to its striking appearance, reminiscent of the long and snake-like mythical Chinese dragon."
The long neck of Dinocephalosaurus orientalis has drawn comparison with the neck of Tanystropheus hydroides, another strange marine reptile from the Middle Triassic period of both Europe and China.
Both reptiles were of similar size and have several features of the skull in common. However, the Dinocephalosaurus has many more vertebrae both in the neck and in the torso, giving it a much more snake-like appearance.
Researchers from Scotland, Germany, US and China studied Dinocephalosaurus orientalis over the course of 10 years at the Institute of Vertebrate Palaeontology and Palaeoanthropology, Beijing, part of the Chinese Academy of Sciences.
Despite superficial similarities, Dinocephalosaurus was not closely related to the famous long-necked plesiosaurs that only evolved around 40 million years later and which are thought to have been the inspiration for the Loch Ness monster.
Professor Li Chun from the institute said: "This has been an international effort. Working together with colleagues from the US, the United Kingdom and Europe, we used newly discovered specimens housed at the Chinese Academy of Sciences to build on our existing knowledge of this animal.
"Among all of the extraordinary finds we have made in the Triassic of Guizhou province, Dinocephalosaurus probably stands out as the most remarkable."
The paper describing the animal is published in full in the academic journal Earth And Environmental Science: Transactions Of The Royal Society Of Edinburgh - forming the entirety of the latest volume.
-- BERNAMA
