For those of us who grew up in the 1970s, the dinosaur world is barely recognisable nowadays. Remember Brontosaurus? The NYT and Project Exploration detail what is known so far of a newly-discovered dinosaur that roamed Niger back when the Atlantic was a series of puddles. A relative of Diplodocus, the tiny-brained Nigersaurus taqueti was built like a prehistoric fernmower.

The dinosaur’s small skull, excavated in 1997, proved revealing. CT scans, analyzed by Lawrence M. Witmer of Ohio University, showed details of the braincase and inner ear, from which the scientists inferred the animal’s head posture. Neck bones also indicated that it could not look up. Its muzzle was angled to the ground, unlike the forward-pointing snouts of most other dinosaurs.

The muzzle itself was odd. In contrast to other plant-eating dinosaurs, this one had more than 50 columns of teeth, all lined up along the jaws’ front edges, forming, in effect, foot-long scissors.

The CT scans of the jawbones showed up to nine replacement teeth stacked behind each cutting tooth. When one wore out, another immediately took its place, at a rate, perhaps, of one a month in each column.

“Among dinosaurs,” Dr. Sereno said, “Nigersaurus sets the Guinness record for tooth replacement.”

Categories: Science