A newly found plant-eating dinosaur might have been a species’ “final gasp” throughout a interval when Earth’s warming local weather compelled huge modifications to international dinosaur populations.
The specimen, named Iani smithi after Janus, the two-faced Roman god of change, was an early ornithopod, a gaggle of dinosaurs that in the end gave rise to the extra generally identified duckbill dinosaurs equivalent to Parasaurolophus and Edmontosaurus. Researchers recovered a lot of the juvenile dinosaur’s skeleton – together with cranium, vertebrae and limbs – from Utah’s Cedar Mountain Formation.
Iani smithi lived in what’s now Utah throughout the mid-Cretaceous, roughly 99 million years in the past. The dinosaur’s most placing characteristic is its highly effective jaw, with enamel designed for chewing by way of powerful plant materials.
The mid-Cretaceous was a time of huge modifications, which had huge results on dinosaur populations. Elevated atmospheric carbon dioxide throughout this time triggered the Earth to heat and sea ranges to rise, corralling dinosaurs on smaller and smaller landmasses. It was so heat that rainforests thrived on the poles. Flowering plants took over coastal areas and supplanted regular meals sources for herbivores.
In North America, big plant-eating sauropods – as soon as titans of the panorama – had been disappearing, together with their allosaurian predators. On the identical time, smaller plant eaters, like early duckbills and horned dinosaurs, and feathered theropods like tyrannosaurs and large oviraptorosaurs, had been arriving from Asia.
Enter Iani smithi, distinctive not solely as a result of it’s newly found, but in addition due to its rarity within the North American fossil report and its place in dinosaur historical past.
“Discovering Iani was a streak of luck. We knew one thing prefer it lived on this ecosystem as a result of remoted enamel had been collected right here and there, however we weren’t anticipating to come across such a stupendous skeleton, particularly from this time in Earth’s historical past. Having an almost full cranium was invaluable for piecing the story collectively,” says Lindsay Zanno, affiliate analysis professor at North Carolina State College, head of paleontology on the North Carolina Museum of Pure Sciences, and corresponding writer of the work.
Zanno and her group used the well-preserved skeleton to investigate the evolutionary relationships of Iani and had been shocked – and a bit skeptical – of the outcomes.
“We recovered Iani as an early rhabdodontomorph, a lineage of ornithopods identified nearly solely from Europe,” Zanno says. “Not too long ago, paleontologists proposed that one other North American dinosaur, Tenontosaurus – which was as frequent as cattle within the Early Cretaceous – belongs to this group, in addition to some Australian critters. If Iani holds up as a rhabdodontomorph, it raises plenty of cool questions.”
Key amongst these is, may Iani be a final gasp, a witness to the tip of a as soon as profitable lineage? Zanno thinks that learning this fossil within the context of environmental and biodiversity modifications throughout the mid-Cretaceous will give us extra perception into the historical past of our planet.
Iani smithi is known as for Janus, the two-faced god who symbolized transitions – an apt identify, given its place in historical past.
“Iani would be the final surviving member of a lineage of dinosaurs that when thrived right here in North America however had been finally supplanted by duckbill dinosaurs,” Zanno says. “Iani was alive throughout this transition – so this dinosaur actually does symbolize a altering planet.
“This dinosaur stood on the precipice,” she says, “in a position to look again on the means North American ecosystems had been prior to now, however shut sufficient to see the long run coming like a bullet prepare. I believe we will all relate to that.”