| Emiliasaura | |
|---|---|
 | |
| Speculativelife restoration as a rhabdodontomorph | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Clade: | †Ornithopoda |
| Clade: | †Iguanodontia |
| Clade: | †incertae sedis |
| Genus: | †Emiliasaura Coria et al.,2025 |
| Species: | †E. alessandrii |
| Binomial name | |
| †Emiliasaura alessandrii Coria et al., 2025 | |
Emiliasaura (meaning "Emilia's lizard") is an extinct genus ofiguanodontianornithopod dinosaurs from theEarly Cretaceous (Valanginian)Mulichinco Formation ofNeuquén Province, Argentina. The genus contains asingle species,Emiliasaura alessandrii, known from three individual specimens.Emiliasaura was initially described as arhabdodontomorph. If this identification is correct, it would represent the oldest member of this clade and the first named from South America. However, a later analysis of rhabdodontomorphs failed to recoverEmiliasaura within this clade, instead placing it as astyracosternan.
During the summer of 2009, Carlos Alessandri discovered productive outcrops of theMulichinco Formation (Paraje Pilmatué locality) 9 kilometres (5.6 mi) northeast of the city ofLas Lajas inNeuquén Province, Argentina. The partial skeleton of a medium-sized ornithopod was collected in March of that year, comprising part of the leftscapula andcoracoid, the lefthumerus, and a complete right hindlimb. During fieldwork conducted two years later, on the shore of Pilmatué Creek 1 km (0.62 mi) northeast of the previous quarry, a second partial ornithopod skeleton was found, comprising much of the right hindlimb and foot, parts of bothpelvic girdles, threesacral and eightcaudal vertebrae, ninechevrons, and associatedossified tendons. An isolateddorsal vertebra was also recovered in association with a partial skeleton referred to the sauropodPilmatueia.[1]
After being announced in October 2024 in a non-finalizedpreprint, Coria et al. (2025)describedEmiliasaura alessandrii as a new genus and species of ornithopod based on these fossil remains. The first collected specimen, cataloged as MLL-Pv-001, was established as theholotype, and the second specimen, MLL-Pv-006, as theparatype. The isolated dorsal vertebra was also referred to the species. The specimens are accessioned at the Museo de Las Lajas in Argentina. Thegeneric name,Emiliasaura, honors Emilia Ondettia de Fix, the founder of the first museum in Las Lajas. Thespecific name, honors Carlos Alessandri, discoverer of the holotype.[1]
Based onhistological research, Coria et al. (2025) identified the specimens ofEmiliasaura as belonging to somatically immature, or subadult, individuals. Sincebone modeling was still occurring at the time of death, the animals were likely still growing and had not reached their full body size.[1]
In their 2025 description ofEmiliasaura, Coria et al. scored it in thephylogenetic dataset of Poole (2022).[2] They found it to be the most basal member of theRhabdodontomorpha. This would makes it the oldest known member of the clade and the first one known from South America. Their results are displayed in thecladogram below:[1]
In a later 2025 publication focused on European rhabdodontomorphs, Czepiński & Madzia includedEmiliasaura in an updated version of the comprehensive phylogenetic dataset of Fonseca et al. (2024).[3] This matrix consistently recoveredEmiliasaura withinDryomorpha, as an early-divergingstyracosternan. The authors concluded that, while they had not observed the material in detail,Emiliasaura can most likely be regarded as a genus outside Rhabdodontomorpha. These results (implied weighting, K=21) are displayed in the cladogram below:[4]
Emiliasaura is known from theMulichinco Formation, which dates to theValanginian age of the earlyCretaceous period.[1] Several other dinosaurs are known from this formation, including thedicraeosauridPilmatueia,[5] an indeterminatediplodocid,[6] an indeterminate possible dicraeosaurid,[7] and thecarcharodontosauridLajasvenator.[8] Plants known from the formation include thetree fernTempskya[9] andpodocarp conifer trees.[6]
