Tiny dinosaur on verge of swearing off meat

By Julie Steenhuysen

CHICAGO (Reuters) - A rare juvenile skull of a 190 million-year-old dinosaur may help explain when an important group of plant eaters branched off from carnivorous cousins, U.S. and British researchers said on Thursday.

The tiny skull belonged to a young Heterodontosaurus. Its tooth structure -- sharp canine teeth for biting and tearing and flat grinding teeth -- suggest the tiny creature was evolving from a meat eater to a plant eater, the scientists said.

"This juvenile skull indicates that these dinosaurs were still in the midst of that transition," said Laura Porro, a post-doctoral student at the University of Chicago, who described the skull in the Journal of Vertebrate Paleontology.

Porro came across the skull in a drawer in the Iziko South African Museum in Cape Town, South Africa, while researching the eating habits of adults of this type of dinosaur, which belonged to the herbivore order ornithischians that lived during the Early Jurassic period of South Africa.

It was dug up in the 1960s but never identified.

Heterodontosaurus had an unusual combination of teeth, with large fang-like canines at the front of their jaws and worn, molar-like grinding teeth at the back.

Porro said paleontologists had thought the canines were sexually dimorphic -- a characteristic present only in adults of one gender in a species like antlers in male deer.

But the presence of long, serrated canines in the juvenile suggest they were common to both genders, Porro said.