Researchers are considering the recently discovered Iani smithi (Iani), a mid-Cretaceous plant-eating dinosaur, a “last gasp” of a species as the planet’s climate warmed and altered life for its prehistoric inhabitants.
According to a recent study from North Carolina State University, I. smithi was an early ornithopod — a species that would eventually lead to duckbill dinosaurs like Parasaurolophus and Edmontosaurus — that lived 99 million years ago. Researchers found the nearly intact fossil — including vertebrae, skull and limbs — of I. smithi in Utah’s Cedar Mountain Formation.
A Unique Find in the Fossil Record
The I. smithi discovery is unique because the fossil dates back to the middle of this significant transition period. According to the press release, this fossil is also rare in North America.
“Finding Iani was a streak of luck,” says Lindsay Zanno, associate research professor at North Carolina State University and co-author of the study, in a press release. “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.”
The research team analyzed I. smithi’s remains and was a bit baffled by the results.
“We recovered Iani as an early rhabdodontomorph, a lineage of ornithopods known almost exclusively from Europe,” Zanno says in a press release. “Recently, paleontologists 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.”
A Warmer Climate
The Cretaceous period was warm, with little to no ice at the North or South Pole. According to a press release, the mid-Cretaceous period was a time of significant change that greatly impacted dinosaur populations, including I.smithi and its relatives.
The warm atmosphere gave rise to flowering plant life that overtook food sources for herbivores. The warmer weather also caused sea levels to rise, which formed shallow inland seas. This created less land mass for dinosaurs to live on, so larger herbivores like sauropods — long-necked dinosaurs — began to dwindle in number.
As sauropods and their predators — typically allosaurs — disappeared, other dinosaurs, such as tyrannosaurs and oviraptorosaurs, moved into the area.
A Last Gasp
One of the biggest questions Iani could answer is whether or not this species was a “last gasp” or the end of a dinosaur lineage. According to a press release, Zanno believes studying the fossil based on biodiversity and environmental changes could shed light on the planet’s history.
“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,” Zanno says in a press release. “Iani was alive during this transition — so this dinosaur really does symbolize a changing planet."
Researchers named Iani smithi or Iani after the Roman god Janus, a two-faced god representing change and transition. The month of January is named after Janus or Ianuarius in Latin.