A newly discovered dinosaur had a fearsome set of teeth – to chew rubbery plants as he was a vegetarian.
The species lived in what is now Utah in the United States during the mid-Cretaceous period, around 99 million years ago.
The specimen, named Iani smithi after Janus – the two-faced Roman god of change, was an early ornithopod, a group of mostly bipedal herbivores that also includes famous examples such as Iguanodon and Tenontosaurus.
Scientists say that the ornithopods ultimately gave rise to the more commonly known duckbill dinosaurs such as Parasaurolophus and Edmontosaurus.
They believe Iani smithi may have been a species’ “last gasp” during a period when Earth’s warming climate forced massive changes to dinosaur populations.
Researchers recovered most of the juvenile dinosaur’s skeleton – including skull, vertebrae and limbs – from Utah’s Cedar Mountain Formation.
They say the dinosaur’s most striking feature is its powerful jaw, with teeth designed for chewing through tough plant material.
The research team explained that the mid-Cretaceous was a time of major changes, which had huge effects on dinosaur populations.
A rise in atmospheric carbon dioxide at the time caused the Earth to warm and sea levels to rise, corralling dinosaurs on smaller and smaller landmasses.
It was so warm that rainforests thrived at the poles, while flowering plant life took over coastal areas and supplanted normal food sources for herbivores.
In North America, giant plant-eating sauropods – once titans of the landscape – were disappearing, along with their allosaurian predators.
At the same time, smaller plant eaters, such as early duckbills and horned dinosaurs, and feathered theropods such as tyrannosaurs and enormous oviraptorosaurs, were arriving from Asia.
Study lead author Professor Lindsay Zanno, of North Carolina State University, said: “Finding Iani was a streak of luck.
“We knew something like it lived in this ecosystem because isolated teeth had been collected here and there, but we weren’t expecting to stumble upon such a beautiful skeleton, especially from this time in Earth’s history.
“Having a nearly complete skull was invaluable for piecing the story together.”
Zanno and her team used the well-preserved skeleton to analyze the evolutionary relationships of Iani and were surprised by the results.
She said: “We recovered Iani as an early rhabdodontomorph, a lineage of ornithopods known almost exclusively from Europe.
“Recently, palaeontologists proposed that another North American dinosaur, Tenontosaurus – which was as common as cattle in the Early Cretaceous – belongs to this group, as well as some Australian critters.
“If Iani holds up as a rhabdodontomorph, it raises a lot of cool questions.”
She explained that key among those question is whether Iani could be a “last gasp” – a witness to the end of a once successful lineage.
Zanno believes that studying this fossil in the context of environmental and biodiversity changes during the mid-Cretaceous will give more insight into the history of our planet.
She said: “Iani may be the last surviving member of a lineage of dinosaurs that once thrived here in North America, but were eventually supplanted by duckbill dinosaurs.
“Iani was alive during this transition – so this dinosaur really does symbolize a changing planet.”
Zanno added: “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.”
Produced in association with SWNS Talker
Edited by Saba Fatima and Newsdesk Manager
