First brachiosaur tooth found in Asia.

A brachiosaur tooth found in South Korean sediments represents the first evidence that this huge, plant-eating dinosaur once roamed Asia, say the researchers who dug up the tooth.

Brachiosaur teeth are easy to recognize, explains Jong-Deock Lim, a paleontologist at the Natural History Museum at the University of Kansas in Lawrence. When the top and bottom teeth wore against each other, the crowns developed chisel-shaped surfaces that were self-sharpening. Many large, herbivorous dinosaurs instead had rounded, spoon-shaped teeth, Lim says.

The 3-centimeter-long brachiosaur tooth was found near Jingu, South Korea, along a dinosaur trackway. The tracks had been imprinted in sediments laid down along the shore of a freshwater lake between 110 and 125 million years ago. Lim and his colleagues describe their discovery, which has been posted online, in an upcoming issue of NATURWISSENSCHAFTEN.

Some of the footprints in the trackway measure up to 1 meter across and were made by large sauropod dinosaurs--a group that includes brachiosaurs. Although the imprints haven't been linked to a specific type of sauropod, Lim says, the tooth indicates at least some could have been made by a brachiosaur.

Because no bones were found with the tooth, it probably fell out or was broken off, Lim says. The size of the tooth and the amount of wear indicate the stray fossil came from an adult brachiosaur. The tooth's shape suggests that it came from the upper left portion of the animal's mouth, Lim says. Brachiosaurs took advantage of their long necks to feed on conifers, tree ferns and other tall, tough vegetation.

The dinosaur that shed this tooth in the Korean peninsula was probably similar in size to African brachiosaurs--3 to 5 m tall at the shoulder and more than 25 m long.

"This tooth indicates there are brachiosaur bones yet to be found in the area," Lim says. The discovery also may shed light on ancient global geography, hinting at a previous land link between Asia and Africa.

--S.P