Before he trekked around the globe unearthing fossils as a University of Chicago paleontologist and "National Geographic" explorer-in-residence, Paul C. Sereno excavated piles of long-forgotten rocks in the back rooms of Harvard's Natural History Museum. It was there that he discovered the Pegomastax africanus, a new species of dinosaur in the heterodontosaurus genus. After decades of research, he unveiled the new dinosaur last week in the online journal "ZooKeys."

In the late 1960s, Fisher Professor of Natural History, Emeritus A. W. "Fuzz" Crompton brought back a collection of fossils from an expedition into South Africa in search of evidence of the heterodontosaur. But back in Cambridge, Crompton's research moved in a different direction. "I'd sort of lost interest in that particular genus," he said in a phone interview.

Two decades later, Sereno, then a graduate student at the American Museum of Natural History and Columbia University, commuted to Harvard to study Crompton's abandoned collection. He frequently stayed in the Harvard Museum of Natural History's back rooms late into the night. "I would spook some people out, among the fossils at midnight, one o'clock, two o'clock," Sereno said in a phone interview. "I would often find myself alone with a rhino skull over my shoulder at night in the museum."

One day, a preparator pointed out an unusual specimen to Sereno. Within the slab of red rock were the remains of a tiny heterodontosaur. "I looked at it and I knew pretty instantly it was a new taxon," Sereno recalled.

But Sereno wasn't content to publish his discovery out of context. "To find this one group I was going to have to travel the world," he said. "I knew I had a new taxon already, in the bag, but I really wanted to write the handbook on this group."

And that's what he did. At 225 pages, Sereno's newly published article helps to explain the evolution of one of the earliest groups of herbivorous dinosaurs.

Pegomastax africanus stood under two feet tall with a one-inch jaw, a short beak, and sharp teeth. He has concluded that it used its massive fangs for self-defense rather than for hunting and eating meat. His finding provides evidence for the disputed theory that all heterodontosaurs were herbivores.

"He's used the specimen to really do a revision of the whole family," Crompton said.

Sereno hopes that, even if it has no further implications, his discovery will compel universities to continue funding paleontology and natural history museums and inspire students to continue frequenting them. "Many of us who hang around collections are bound to discover some amazing things," Sereno said.