A peculiar amphibian that was clad in bony armor 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. The creature called Gerrothorax pulcherrimus, which lived alongside some of the early dinosaurs, 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. Scientists think Gerrothorax lurked at the bottom of a lake, then with a sudden movement of the skull created a mouth gape that entrapped any fish unfortunate enough to swim by. Gerrothorax measured about 3 feet (1 meter) long and was stoutly protected by bony body armor reminiscent of chain mail. With a special adaptation of the joint between its skull and first neck vertebra, Gerrothorax 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. Gerrothorax is one of a group of odd amphibians called plagiosaurs with no modern descendants that 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. __
