New dinosaur species discovered in utah may have been victim of climate change

A recently discovered herbivorous dinosaur may have represented a species’ final effort to survive in the face of significant shifts in global dinosaur populations caused by Earth’s warming climate. Known as Iani smithi, after Janus, the two-faced Roman god of change, this dinosaur belonged to the early ornithopod group, which eventually gave rise to well-known duckbill dinosaurs like Parasaurolophus and Edmontosaurus. Researchers unearthed a substantial portion of the juvenile dinosaur’s skeleton, including its skull, vertebrae, and limbs, from Utah’s Cedar Mountain Formation. The findings of this study have been published in the journal PLoS ONE.

Iani smithi existed around 99 million years ago during the mid-Cretaceous period in what is now Utah. What stands out most about this dinosaur is its formidable jaw, featuring teeth that were specifically adapted for chewing tough plant material.

The mid-Cretaceous era witnessed significant transformations that had profound impacts on dinosaur populations. The elevated levels of atmospheric carbon dioxide during this time led to global warming and rising sea levels, resulting in the confinement of dinosaurs to increasingly smaller landmasses. The climate was so warm that rainforests flourished even at the Earth’s poles. Coastal regions became dominated by flowering plants, which replaced the usual food sources for herbivores.

3D reconstruction of the skull of Iani smithi. Credit: Haviv Avrahami, CC-BY 4.0 (

In North America, the once dominant giant plant-eating sauropods and their allosaurian predators were vanishing. Simultaneously, smaller herbivores such as early duckbills and horned dinosaurs, along with feathered theropods like tyrannosaurs and massive oviraptorosaurs, were making their way from Asia.

Enter Iani smithi, a truly remarkable discovery. Not only is it a newly unearthed dinosaur, but it is also incredibly rare in the North American fossil record, making it a significant find in the context of dinosaur history.

“Coming across Iani was an incredible stroke of luck. We were aware that something similar lived in this ecosystem based on a few scattered teeth that had been found here and there. However, stumbling upon such an exquisitely preserved skeleton, particularly from this specific period in Earth’s history, exceeded our expectations. The near-complete skull was immensely valuable in unraveling the story,” says Lindsay Zanno, an associate research professor at North Carolina State University, head of paleontology at the North Carolina Museum of Natural Sciences, and the corresponding author of the study.

Location of holotype locality for Iani smithi. (A) Global map showing location of Mussentuchit Member outcrop in central Utah, western North America, and a stratigraphic section at the quarry with dated ash horizons; and (B) graphical representation of preserved skeletal elements of the holotype specimen. Preserved elements are colored on the left facing skeletal whether they derive from the right or left side of the body. Exact positions of chevrons and ribs unknown due to poor preservation. Credit: Zanno et al., 2023, PLOS ONE, CC-BY 4.0 (

Zanno and her research team extensively studied the remarkably well-preserved skeleton of Iani, leading them to examine the evolutionary connections of this dinosaur. However, they were both surprised and somewhat skeptical of the findings.

“We identified Iani as an early member of the rhabdodontomorph lineage, a group of ornithopods primarily known from Europe,” explains Zanno. “Recently, some paleontologists suggested that another North American dinosaur, Tenontosaurus—which was as abundant as cattle in the Early Cretaceous—also belongs to this group, along with certain Australian species. If Iani indeed proves to be a rhabdodontomorph, it raises intriguing questions.”

One significant question revolves around whether Iani could represent the final existence of a once thriving lineage—a species on the brink of extinction. Zanno believes that studying this fossil within the context of the environmental and biodiversity changes during the mid-Cretaceous period will provide valuable insights into our planet’s history.

The name Iani smithi is derived from Janus, the two-faced god symbolizing transitions, which aptly reflects its place in history.

“Iani might be the last surviving member of a lineage of dinosaurs that once flourished in North America but eventually yielded to the dominance of duckbill dinosaurs,” states Zanno. “Iani witnessed this transition—a dinosaur that truly embodies a changing planet.”

She adds, “This dinosaur stood at the edge, capable of looking back at the past North American ecosystems while being close enough to witness the approaching future like a high-speed train. I believe we can all relate to that.”

Source: North Carolina State University

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