New 100 Million-Year-Old Dinosaur Discovered in Utah With 'Beautiful' Skull

A previously unknown dinosaur species that lived around 100 million years ago has been discovered in Utah.

The new species—named Iani smithi after Janus, the two-faced Roman god of entrances and thresholds—was a plant-eater measuring around 10 feet in length, according to an author of a study published on Thursday in the journal PLOS ONE.

The dinosaur roamed North America in the latter half of the Cretaceous period—the geological era that spanned around 145 to 66 million years ago.

"They ate tough plant material and had powerful jaws," Lindsay Zanno, an author of the study affiliated with the North Carolina Museum of Natural Sciences and North Carolina State University, told Newsweek.

The period in which Iani smithi lived was marked by significant warming in Earth's climate. The latest discovery sheds new light on this tumultuous era, one in which global dinosaur populations experienced massive shifts as a result of the climatic changes.

Researchers uncovered the specimen—including the skull, vertebrae and limbs—in Utah's Cedar Mountain geological formation, which contains sediments from the middle of the Cretaceous. The individual found appears to be a juvenile.

"The skeleton is mostly complete, and well-preserved with a beautiful skull," Zanno said.

Iani smithi was an early ornithopod—a group of dinosaurs that ultimately gave rise to duck-billed dinosaurs such as Parasaurolophus and Edmontosaurus—the researchers said.

A Local Extinction Prompted by Climate Change

At the boundary between the Early and Late Cretaceous—when Iani roamed North America, the Earth was undergoing significant changes. But their impact is not yet well understood.

"During the mid-Cretaceous, Earth experienced a temperature spike known as the Cretaceous Thermal Maximum," Zanno said. "Greenhouse gas concentrations were three to four times higher than today, sea levels rose between 500-1,000 feet above today's levels. Earth's poles were blanketed with temperate rain forests."

"Back then, the climate change was caused by volcanic gasses. This climate change prompted a local extinction of dinosaur groups in North America," she said.

For more than a decade, the scientists have been working to piece together the story of how North American dinosaur populations changed during the mid-Cretaceous.

"What happened to the dinosaur groups that were living here before this time? How did rising sea levels, global warming, and shrinking habitat during the mid-Cretaceous affect life on land? These are huge questions that require a lot of data to address," Zanno said.

"This is why we've been hunting for new dinosaurs in rocks of mid-Cretaceous age, to fill in the gaps in our data. Iani is the newest dinosaur to come from this effort."

A Dinosaur 'Close Enough to See the Future Coming Like a Bullet Train'

At this time in North America, giant plant-eating sauropods and their allosaurian predators were disappearing. In the same period, smaller plant-eaters—like early duckbills and horned dinosaurs—as well as feathered theropods like tyrannosaurs were arriving from Asia.

The team's analysis found that Iani is the first known early ornithopod that survived into the Late Cretaceous in North America. They determined, to their surprise, that Iani was an early rhabdodontomorph—a lineage of ornithopods known almost exclusively from Europe.

Early ornithopods were once "extremely common" across North American ecosystems but scientists did not previously know that they survived into the Late Cretaceous on the continent, Zanno said.

The discovery of Iani has helped scientists to link the extinction of early ornithopods in North America with a major period of global warming.

"Discoveries like Iani are helping us to piece together the puzzle of why these dinosaurs disappeared," Zanno told Newsweek.

The researchers said there is a possibility that Iani was the last surviving member of its lineage. The species was eventually replaced by duck-billed dinosaurs.

"Iani was alive during this transition—so this dinosaur really does symbolize a changing planet," Zanno said in a statement.

The name of the new dinosaur species is a nod to this period of change—the Roman god Janus was one of transitions.

"This dinosaur stood on the precipice, able to look back at the way North American ecosystems were in the past, but close enough to see the future coming like a bullet train. I think we can all relate to that."