The giant tooth of a prehistoric sea monster has been found high up in the Swiss alps, a new study said on Thursday.

The tooth was discovered along with two skeletal remains believed to come from ichthyosaurs — massive marine reptiles with small heads and elongated bodies that ruled the oceans in the early Triassic Period.

Published in the Journal of Vertebrate Paleontology, the report analyzed one skeleton containing 10 rib fragments and a vertebra, suggesting a huge animal about 20 meters (66 feet) long, about the size of a large sperm whale. The second fossil suggested an ichthyosaur about 15 meters long.

But "the tooth is particularly exciting," said lead author Martin Sander, of the University of Bonn, seeing as larger ichthyosaurs so far discovered had appeared to be toothless.

With its root at 60 millimeters (2.4 inches) in diameter, it's the largest-ever tooth found for the extinct reptiles.

Mysterious giant 'fish lizard' predating the dinosaurs

The ichthyosaur — which literally translates from ancient Greek to "fish lizard" — was one of the largest animals to have ever lived, growing up to 20 meters and weighing up to 80 metric tons, heavier than the largest sperm whale ever recorded.

The beasts are thought to have first appeared roughly 250 million years ago after the Permian-Triassic extinction event, sometimes called "the great dying," which saw over 95% of sea life wiped out.

Ichthyosaurs died off 100 million years ago and left behind a scant trail of fossil remains, mystifying researchers.  Dinosaurs, which went extinct much later, have better-preserved remains.

The specimens studied in the new report were actually unearthed in geological surveys between 1976 and 1990 but are only now being analyzed in detail.

Ichthyosaurs were previously thought to have survived in the deep ocean, zipping through the water at speeds of over 22 miles per hour (36.5 kph) and navigating the pitch blackness with their gigantic eyes.

But these were found in an area that was once a shallow, coastal water body, leading scientists to speculate on how the animals lived there.

During their lifetimes, the three newly analyzed reptiles likely swam in waters around the supercontinent Pangaea. The subsequent tectonic shifts that followed, pushing the Alpine mountain range up out of the ground, explains them being found in an area that's now far above sea level.

Other ichthyosaur fossils were previously found in Canada and the United Kingdom. The largest ichthyosaur remains discovered had suggested an animal about 26 meters in size — and toothless.

Before now, scientists suspected that larger ichthyosaurs perhaps did not have teeth like smaller species.

It's unclear why the water giants died out, but  some experts link their extinction to volatile environmental conditionsduring the late Cretaceous period, when the earth was much warmer.

 sl/msh (AFP, Reuters)