An enormous amphibian that lived 240 million years ago in Antarctica could really sink its teeth — all three rows of them — into prey, considering it had an extra set of large, sharp teeth on the roof of its mouth.
Its tooth-packed mouth, 2.75-foot-long head and 15-foot body help to explain how this beast, Kryostega collinsoni, was Antarctica's top known Triassic predator.
The animal resembled a modern crocodile but was actually a temnospondyl, a prehistoric amphibian that was an early relative of salamanders and frogs. Because of their odd mixture of characteristics, members of this group are sometimes nicknamed "crocamanders" or "frogodiles."
Most temnospondyls have roof-of-the-mouth teeth, but those found in the new species are larger than usual, matching the teeth in its upper and lower jaws.
"Palatal teeth are very common among Permian and Triassic temnospondyls and probably functioned as fangs to retain struggling prey in the mouth," lead author Christian Sidor explained to Discovery News.
"Prey was probably swallowed whole or torn into smaller pieces — no chewing," added Sidor, who is a University of Washington associate professor of biology and curator of vertebrate paleontology at the Burke Museum of Natural History and Culture.
He and colleagues Ross Damiani and William Hammer made their determinations after analyzing a piece of fossilized snout from the amphibian, which they liken to "a salamander on steroids."
The fossil was found in the Fremouw Formation of Antarctica, indicating the amphibian lived in an ancient freshwater river that existed when all of the world's land masses were joined together in the supercontinent Pangea.
The findings are published in this month's Journal of Vertebrate Paleontology.
Sidor suspects Kryostega "probably ate mostly fish and other amphibians living in the river alongside it, 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."
Little is known about Antarctica's flora and fauna of this time, but scientists previously unearthed the remains of another large amphibian, Parotosuchus, as well as evidence of dicynodonts -- tusked, stocky plant eaters that could be as small as a rat or as large as an ox. Burrows found in river bottoms suggest insects were also present.
Although dinosaurs would not emerge in the region until later, Antarctica was probably more supportive of life then than it is now.
"The part of Pangea that is now Antarctica was substantially warmer in the Middle Triassic than it is today," said Sidor, "but I would never claim that it was tropical or balmy."
"Computer climate simulations suggest that it was seasonally very harsh, with periods of complete darkness," he added.
Sebastien Steyer, a paleontologist at the Museum of Natural History in Paris, told Discovery News that he thinks the new finding "is a great one."
"This discovery of a fossil amphibian brings new information on the paleofauna of Antarctica before dinosaurs (emerged there)," Steyer explained.
He added, "The 'paleoworld' of Antarctica is potentially extremely rich but still poorly known, simply because it is difficult to work there...so this should encourage all the paleontologists to organize expeditions there."