Open Paleo

Emiliasaura

Coria et al., 2024 eh-MEE-lee-uh-SOH-ruh

Named in honor of Emilia (likely a personal name) + Latin saura (lizard): 'Emilia's lizard'.

137.1–132.6 million years ago Valanginian, Early Cretaceous
Early Cretaceous stages

Emiliasaura is an extinct genus of iguanodontian ornithopod dinosaurs from the Early Cretaceous (Valanginian) Mulichinco Formation of Neuquén Province, Argentina. The genus contains a single species, Emiliasaura alessandrii, known from three individual specimens. Emiliasaura was initially described as a rhabdodontomorph. 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 recover Emiliasaura within this clade, instead placing it as a styracosternan.

Under dispute

Emiliasaura alessandrii was described as an early-diverging rhabdodontomorph (Coria and colleagues, 2024) — which would make it the oldest and first South American member of that clade — but the dedicated reanalysis of Czepiński and Madzia (2025) instead recovers it as an early-diverging styracosternan and considers a rhabdodontomorph identity unlikely. No analysis recovers it within Dryosauridae.

Diagnosis

  1. Sigmoidal intercentral articulations in the anterior sacral vertebrae in lateral view
  2. Caudal vertebrae with posteriorly projecting neural spines and spike-like, dorsoposteriorly projecting transverse processes
  3. Closed or absent coracoid foramen
  4. Distinctive notch on the medial side of the fibula flanked by two thick edges
  5. Second metatarsal with an asymmetrical ginglymoid distal articulation and a V-shaped notch on the medial side of the distal end
  6. Pedal digit II with wide but short second and third phalanges and a blunt, hoof-like ungual, contrasting with the claw-like unguals of digits III and IV

Species

Emiliasaura alessandrii Coria et al., 2024

Type species

Named for Carlos Alessandri, who discovered the productive outcrops in 2009 that yielded the holotype.

Holotype
MLL-Pv 001 , Museo Municipal de Las Lajas
Material
Proximal end of the left scapula, incomplete left coracoid, left humerus, and a complete articulated right hind limb (femur, tibia, fibula, tarsus, and pes).
Horizon
Mulichinco Formation, Valanginian, Early Cretaceous , 137.1–132.6 million years ago
Locality
Quarry #1, Paraje Pilmatué, Neuquén, Argentina

References

  1. Coria, R. A.; Cerda, I. A.; Escaso, F.; Baiano, M. A.; Bellardini, F.; Braun, A.; Coria, L. M.; Gutierrez, J. M.; Pino, D.; Windholz, G. J.; Currie, P. J.; Ortega, F. (2024). First Valanginian (Early Cretaceous) ornithopod (Dinosauria, Ornithischia) from Patagonia. Cretaceous Research 166. Elsevier BV. doi:10.1016/j.cretres.2024.106027

    Describing paper; recovered Emiliasaura as an early-diverging rhabdodontomorph, the oldest member and first from South America.

    coria2024a
  2. Poole, K. E. (2022). Phylogeny of iguanodontian dinosaurs and the evolution of quadrupedality. Palaeontologia Electronica 25(3): a30. doi:10.26879/702

    Phylogeny of iguanodontian dinosaurs; the character framework underlying the rhabdodontomorph hypothesis for this taxon.

    poole2022a
  3. Czepiński, Ł.; Madzia, D. (2025). Exploring the diversity and disparity of rhabdodontomorph ornithopods from the Late Cretaceous European archipelago. Scientific Reports 15(1). Springer Science and Business Media LLC. doi:10.1038/s41598-025-98083-z

    Recovered Emiliasaura as an early-diverging styracosternan and considered a rhabdodontomorph identity unlikely.

    czepiński2025a
  4. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Assessment in the Princeton Encyclopedia of Dinosaurs.

    jones2026a