EXTREME DINOSAUR: AFRICA’S FERN-MOWER

What makes Nigersaurus so extreme?
Nigersaurus has some extremely unusual anatomical features unlike any seen before in a plant-eating dinosaur.

• Its jaws are wider than the rest of the skull
• The extremely lightweight skull fed an elephant-sized body
• The teeth are packed into batteries along the front of the jaws.

Photos © M. Hettwer With tooth rows composed of many small, chisel-tipped teeth, the jaws of Nigersaurus closed like dinosaurian scissors, cropping a mouthful of plants with each bite.

This strange dinosaur had a body that weighed as much as an elephant (about 4000 pounds) and spent most of its day with its mouth close to the ground mowing down patches of ferns and other plants.

Nigersaurus belongs to a group of long-necked dinosaurs (sauropods) called “diplodocoids.”Nigersaurus is a significant discovery because offers a new perspective on how some of these dinosaurs ate. Diplodocoids have been regarded as “leaf strippers,” raking down vegetation well above the ground. Several lines of evidence, however, suggest that Nigersaurus and perhaps its older North American cousin, Diplodocus, cropped plants close to the ground, more like long-necked cows.

AIR-FILLED BONES

Photo © P. Sereno This is a vertebra (back bone) of Nigersaurus. The neural arch is composed of extremely thin bone. The centrum of the vertebra is a hollow shell

Despite weighing as much as an elephant and growing to be a length of 30 feet, the backbone of Nigersaurus is composed of shells of bone.

Large oval openings on each side of the vertebrae (backbone) provide an entry to long air-filled sacs connected to the lung. When the animal was alive, air sacs filled the hollow vertebrae. Other air sacs would have pressed against the neural arches (the upper part of the vertebra) leaving thin plates of bone in between.

The air-filled vertebrae of Nigersaurus are unusual because they are so extreme. That such fragile vertebrae were able to support such a massive body is remarkable.