Tiny Dino With Fangs ID'ed 30 Years After Discovery

Image credit: Photo and sculpting by Tyler Keillor

If you're at a loss when it comes to a Halloween costume, paleontologist Dr. Paul C. Sereno has a suggestion: try a new rare, miniature dinosaur species called pegomastax.

"The pegomastax is a cutie," Sereno, a professor at the University of Chicago, told ABC News today. "I would like to see people wearing pegomastax masks. … They have fangs - canines in the lower and upper jaw. It's perfectly suitable for a Halloween mask."

Sereno, also a National Geographic Society explorer-in-residence, released a report today in the journal ZooKeys, about the pegomastax and its heterodontosaur family, what he called " a weird group of herbivores with canines."

"The significance of the work is lifting the veil on the 'punk-size' dinosaur," Sereno said.

He said that pegomastax, meaning "thick jaw, short snout," was the size of a small cat and looked like a parrot - "an unusual parrot albeit with fangs." He said it had two legs and lived in the Jurassic era and start of the Cretaceous era.

Heterodontosaurus fossils have been found as far apart as Argentina, China and England.

In his report today, Sereno determined that the fangs or canines were "display structures" and good for nipping kin or fending off enemies. He disputed theories that they used the fangs to tear at meat, saying they were strict herbivores.

Sereno also explained that while the dinosaur dwarfs species had evolved from larger dinosaurs, heterodontosaurs were always small and some even got smaller by half.

Sereno first encountered the pegomastax 30 years ago as a graduate student visiting Harvard. At the time, he was working with professor Alfred Crompton, who is now retired but had discovered the heterodontosaurus species while collecting specimens from South Africa during the 1960s.

"My eyes lit up," he said of his pegomastax discovery in 1983. "It was a new species. I left it there. After photographing it and studying it, I took a chance. … I didn't sort of anticipate it would be that interesting."

With newly found bones piling up, according to Sereno, he left the specimen encased in a block on a shelf. He said that years later, while compiling notes on the heterodontosaur fossils he'd encountered in his explorations, he remembered the pegomastax.

By then it was back in South Africa, though, and part of a museum collection. He said the last time he'd seen it was three years.

Sereno said he was still digging deep into the other dinosaur fossils that he'd discovered over time in the field and like pegomastax, not in the field.

"I got overwhelmed with life in the fast lane. … You get buried. Which one do you name?" he told ABC News today. "You just can't get to it all. [You say to yourself]: 'I'm just not going to name this one.'"

"Goes to show: Things can be found on museum shelves for the next generation," he said.

Image credit: Paul Sereno and Carol Abraczinskas