Duck-billed dinosaurs, the hadrosaurs, have puzzled palaeontologists for years. The puzzle? How did these, the dominant herbivores of their time, manage to chew their food with their funny-looking bills?

Mark Purnell of the University of Leicester Department of Geology, UK, has worked it out, and published it in the Proceedings of the National Academy of Sciences (Press release).

Purnell and his colleagues looked at tiny microscopic scratches on the hadrosaur Edmontasurus’s teeth. They decided that rather than moving the bottom jaw like most living creatures today, it was their upper jaw that was hinged and moved up and down, and side to side.

The news has been chewed over (sorry) by a number of outlets, including MSNBC, Zee News and the AP, who get the prize for best headline with “Hadrosaur chowdown_grind, grind, grind”

The research also tells us that the hadrosaurs probably ate mainly leaves, because the scratches weren’t consistent with chomping on twigs or other tough treats.