15-Foot Antarctic "Salamander" Found; Was Toothy Terror

Ker Than
for National Geographic News
September 11, 2008
An ancient, giant, salamander-like amphibian with a particularly nasty bite has been identified from a 240-million-year-old fossil, scientists report.

Dubbed Kryostega collinsoni, the Antarctic creature was about 15 feet (4.57 meters) long and chomped down on prey using sharp teeth that protruded from the roof of its mouth.

Kryostega was the largest land animal alive in Antarctica during the middle Triassic period, when the continent was greener and more hospitable.

A partial skull belonging to the creature was found in modern-day Antarctica in 1986 but was only recently described by scientists.

In its appearance and lifestyle, Kryostega was very similar to modern crocodiles. Unlike crocodiles, however, it was an amphibian and not a reptile.

"You could think of Kryostega as a giant salamander," said study team member Christian Sidor, a paleontologist at the University of Washington.

Make that an unusually toothy giant salamander: Its teeth were enormous compared to with other amphibians, according to Sidor.

Toothy Terror

Kryostega belonged to an ancient lineage of amphibians called temnospondyls, which had tiny teeth attached to their palates.

However the newly named amphibian's fossil had unusual palate teeth: Some of them were larger than the normal teeth on the edge of its mouth.

Kryostega's side teeth were about 1.2 inches (3 centimeters) tall and about the width of an adult human's pinky finger.

Some of its palate teeth were nearly twice as thick and grew up to 1.6 inches (4 centimeters) in height.

"There might be some modern amphibians with small palatal teeth, but nothing as proportionately massive as [Kryostega]," Sidor said.

The new species will be detailed in an upcoming issue of the Journal of Vertebrate Paleontology.

Balmier Antarctica

During Kryostega's time, the continents were still congealed in one supercontinent called Pangaea. (See an illustration of Pangaea breaking up.)

Antarctica itself was located farther north and attached to South Africa, South America, and Australia.

The continent was also much warmer back then, crisscrossed by large rivers and primeval forests.

(Related: "Tiny Fossils Reveal Warm Antarctic Past" [July 25, 2008].)

The first dinosaurs had not yet appeared, but their ancestors, the dinosauromorphs, roamed the Earth, along with other reptiles and the reptile-like ancestors of mammals.

Top Predator

Kryostega was a top predator in Antarctica, Sidor said.

It likely stayed close to water and dined on fish and other amphibians.

"However, like crocodiles, if land-living animals strayed too close to the river's edge, I expect that it would have been able to drag them in," Sidor said.

Sebastian Steyer is an ancient-amphibian expert at the National Museum of Natural History in Paris, France. He was not involved in the study.

The new fossil is a rare and important find, Steyer said, because it sheds light on life during a little-known era of Antarctica's history.

The only other Antarctic creatures known to live during the middle Triassic include one or two other large amphibians, and a burrowing reptile-like mammal.)

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