December 13, 2008

Scientists Find Fossil Remains Of Ancient Armored Amphibian

Scientists say a peculiar, bony armored amphibian prowled warm lakes 210 million years ago, catching fish and other tasty snacks with one of the most unusual bites in the history of life on Earth.

Gerrothorax pulcherrimus lived alongside some of the early dinosaurs and opened its mouth not by dropping its lower jaw, as other vertebrate animals do, instead, it lifted back the top of its head in a way that looked a lot like lifting the lid of a toilet seat.

Harvard University's Farish Jenkins, one of the scientists who describe the mechanics of its bite in the Journal of Vertebrate Paleontology, called it the weirdest, ugliest animal in the world.

"You almost can't imagine holding your jaws still and lifting your head back to take a bite," Jenkins said.

"There are some vertebrates that will lift their heads slightly or the upper jaws (when they bite). Some salamanders do it slightly. Some fish do it slightly. But no animal is known to have done it this extensively," Jenkins added.

Gerrothorax likely lurked at the bottom of a lake, and with a sudden movement of the skull created a mouth gape that entrapped any fish unfortunate enough to swim by.

The giant-sized amphibian measured about 3 feet long and was stoutly protected by bony body armor reminiscent of chain mail. Jenkins said it had a very flat body and very flat head, short, stubby limbs and well-developed gills.

Sharp teeth lined the creatures jaw and the roof of its mouth was studded with large fangs to keep any slippery fish from escaping its bite.

Gerrothorax also sported a special adaptation of the joint between its skull and first neck vertebra so it could raise its head relative to its lower jaw by as much as 50 degrees, giving it the wide gape necessary to swallow its prey.

Belonging to a group of odd amphibians called plagiosaurs, Gerrothorax has no modern descendants since plagiosaurs vanished along with numerous other species 200 million years ago in a mass extinction at the end of the Triassic Period. Its fossils were found in the Fleming Fjord Formation of east Greenland.

Anne Warren of La Trobe University in Melbourne, Australia, said that the same species is found in Greenland as well as Western Europe and Scandinavia, suggesting that their unique structure was hugely successful.

Gerrothorax was armored for necessary protection since it lived alongside massive, crocodile-like reptiles called phytosaurs and larger, predatory amphibians. Other fossils show dinosaurs, flying reptiles called pterosaurs and early mammals lived alongside it.

Image Courtesy Arthur Weasley - Wikipedia


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