Washington Post article about grazing dinosaurs:

The Dinosaur That Peacefully Grazed
Perfectly Adapted Creature Kept Its Head Down, Got New Teeth Once a Month

Friday, November 16, 2007; Page A15

Could an elephant-size dinosaur with a skull so thin that a karate chop would have split it in two, teeth it shed once a month and a brain that, yes, was the size of a walnut, ever be considered one of evolution's success stories?

Paul C. Sereno thinks so.

The University of Chicago paleontologist yesterday unveiled Nigersaurus taqueti, a strange creature that is helping rewrite theories about how long-necked, plant-eating dinosaurs looked and behaved.

Nigersaurus appears to have spent a lifetime with its head in a hangdog position. Using a broad, tooth-filled mouth, it grazed on ferns and horsetails growing at most a couple of feet high. It couldn't even raise its head to horizontal. Getting at trees was out of the question.

Many other dinosaurs -- including the more famous and less bizarre Diplodocus -- probably behaved similarly, using their long necks as ground-mowing booms, not treetop cherry pickers, Sereno believes.

"It took an extreme dinosaur to open our eyes to this cow-like behavior," he said yesterday at the National Geographic Society's headquarters in the District, where a reconstruction of Nigersaurus was mounted. "It is sort of silly to think that something wasn't doing this. But we had missed the cows of the Mesozoic."

Other paleontologists agreed that the new dinosaur will further dispel the notion that long-necked dinosaurs were the prehistoric equivalent of giraffes, holding their heads high overhead.

"It would be hard to imagine a more compelling argument against" that view, said Kent A. Stevens, a computer scientist at the University of Oregon who has done extensive research on dinosaur posture.

(see the rest by following the link)

There is a major argument against a dinosaur that kept its head down to graze on grass. GRASS is a quite modern plant, and hadn't evolved at the time of the dinos. Maybe this dino ate sphagnum moss or ferns, but it wasn't grazing on grass.

SRS