Smithsonian Magazine covers the discovery of a new species of dinosaur, Iani smithi, that’s part of a little-known group of dinosaurs that were around just before the big, famous ones like Tyrannosaurus and Triceratops. They named the new dinosaur after the Roman god Janus, or Ianus, the god of transitions, because Iani might help us understand how those famous dinosaurs came to be:
At a glance, the dinosaur might seem somewhat plain. Iani lacks any horns, plates, spikes or other outstanding features that we often associate with dinosaurs. The details of the reptile’s skeleton, however, identify Iani as a rhabdodontomorph—a little-known group of herbivorous dinosaurs that were only recognized in 2016.
“I was really skeptical about that identification,” [North Carolina Museum of Natural Sciences paleontologist Lindsay] Zanno says, but that uncertainty led the researchers to be extra careful in their analysis. “Skepticism is what makes good science, so I spent a long time scrutinizing the anatomy and our analyses,” she adds. Iani shares some traits with other rhabdodontomorphs that can’t be denied, she says, particularly features of its teeth and skull. These dinosaurs, like the 8-foot long Zalmoxes from Romania and the 26-foot-long Muttaburrasaurus from Australia, make up a group of small- to medium-sized herbivores that spread around the world during the Cretaceous in the days before the more familiar duckbilled dinosaurs evolved.
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Popular depictions of dinosaur eras often compress whole time periods down to relatively narrow slices. The whole of the Cretaceous lasted about 79 million years, from 66 million to 145 million years ago. That’s a broader span of time than the entire post-Cretaceous history of the world, and plenty of time for different groups of dinosaurs to thrive and fall back.
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You can read more of Zanno’s research here, in PLOS One.