A new dinosaur armed with giant claws and teeth was in fact a friendly herbivore – but needed those big choppers to gnaw through rubbery Cretaceous plants.
The species, named Iani smithi, lived in what is now Utah in the US around 99million years ago.
Researchers recovered most of the juvenile dinosaur’s skeleton – including the skull, vertebrae and limbs – from the state’s Cedar Mountain Formation, which has revealed a number of stunning finds over the years.
The team said the dinosaur‘s most striking feature is its powerful jaw, with teeth designed for chewing through tough plant material.
‘Finding Iani was a streak of luck,’ said lead author Professor Lindsay Zanno, from North Carolina State University.
‘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.’
Life in the Cretaceous period looked very different to today – but was also a time of great change.
Rising carbon dioxide levels caused the Earth to warm and sea levels to rise, leading to isolated populations of dinosaurs on increasingly small landmasses. The South Pole was covered by an ancient rainforest, and flowering plant life on coasts supplanted food sources for herbivores.
In North America, giant plant-eating sauropods 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.
Iani was an ornithopod, a group of mostly bipedal herbivores that also includes famous examples such as Iguanodon and Tenontosaurus.
‘We recovered Iani as an early rhabdodontomorph, a lineage of ornithopods known almost exclusively from Europe,’ said Professor Zanno.
‘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.’
One of those is whether Iani was the ‘last gasp’ of a previously successful lineage.
‘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,’ said Professor Zanno.
‘Iani was alive during this transition – so this dinosaur really does symbolise a changing planet.
‘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.’
MORE : Costa Rica crocodile with no mates made herself pregnant in world first
MORE : The evolutionary adaptation that helped dinosaurs to fly: bones like Aero chocolate
