Iani

This article is about the dinosaur. For the region on Mars, see Iani Chaos.

Iani Temporal range: Late Cretaceous (Cenomanian), ~99.5 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Skeletal reconstruction showing known fossil material in green
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	†Ornithischia
Clade:	†Neornithischia
Clade:	†Ornithopoda
Clade:	†Rhabdodontomorpha
Genus:	†Iani Zanno et al., 2023
Species:	†I. smithi
Binomial name
†Iani smithi Zanno et al., 2023

Iani (after Ianus) is an extinct genus of rhabdodontomorph iguanodontian dinosaur from the Late Cretaceous Cedar Mountain Formation of Utah, United States. The genus contains a single species, I. smithi, known from a partial skeleton including the skull. Its discovery serves as a link between the genus Tenontosaurus and the Rhabdodontidae, with both along with Iani being members of the clade Rhabdodontomorpha.^[1]

Discovery and naming

The Iani holotype specimen, NCSM 29373, was discovered in 2014 in sediments of the Cedar Mountain Formation (lower Mussentuchit Member) in Emery County, Utah, United States. The specimen consists of a partial skeleton including a nearly complete, disarticulated skull, cervical, dorsal, sacral, and caudal vertebrae, ribs and haemal arches, partial pectoral and pelvic girdles, and the right arm and leg.^[1]

In 2023, Zanno et al. described Iani smithi as a new genus and species of rhabdodontomorph iguanodontian based on these fossil remains. The generic name, "Iani", alludes to Ianus, the Roman god of transitions, referencing the changing biota of the time. The specific name, "smithi", honors Joshua Aaron Smith and his paleontological contributions.^[1]

Classification

Life reconstruction of Iani

Zanno et al. (2023) recovered Iani as a basal rhabdodontomorph member of the Iguanodontia. They interpreted it as a transitional taxon between Tenontosaurus and other Late Cretaceous rhabdodontomorphs (the Rhabdodontidae). The cladograms below display the results of their phylogenetic analyses using different datasets:^[1]

Topology 1: Poole (2022) dataset[2] Rhabdodontomorpha Muttaburrasaurus Iani Tenontosaurus dossi Tenontosaurus tilletti Rhabdodon Zalmoxes shqiperorum Zalmoxes robustus

Topology 2: Dieudonné et al. (2021) dataset[3] Rhabdodontomorpha Tenontosaurus dossi Tenontosaurus tilletti Iani Rhabdodon sp1 Rhabdodon priscus Zalmoxes shqiperorum Zalmoxes robustus Mochlodon vorosi Mochlodon suessi Transylvanosaurus Vegagete ornithopod Muttaburrasaurus Fostoria

References

1. Zanno, Lindsay E.; Gates, Terry A.; Ayrahami, Haviv M.; Tucker, Ryan T.; Makovicky, Peter J. (2023). "An early-diverging iguanodontian (Dinosauria: Rhabdodontomorpha) from the Late Cretaceous of North America". PLOS ONE. 18 (6). e0286042. Bibcode:2023PLoSO..1886042Z. doi:10.1371/journal.pone.0286042. PMC 10246810. PMID 37285376.
2. Poole K. 2022. "Phylogeny of iguanodontian dinosaurs and the evolution of quadrupedality". Palaeontologia Electronica. 25(3):1–65
3. Dieudonné P.E., Cruzado-Caballero P., Godefroit P. & Tortosa T. 2021. "A new phylogeny of cerapodan dinosaurs". Historical Biology. 33(10): 2335