Open Paleo

Isaberrysaura

Salgado et al., 2017 ih-zah-BEH-ree-SOH-ruh

Named for Isabel Valdueza Berry, who reported the fossil site, combined with Greek 'saura' meaning 'lizard'.

170.9–168.2 million years ago Bajocian, Middle Jurassic
Middle Jurassic stages

Isaberrysaura is an extinct genus of stegosaurian ornithischian dinosaurs from the Middle Jurassic Los Molles Formation of Patagonia, Argentina. The genus contains a single species, I. mollensis, described by Salgado in 2017 based on a single specimen. Salgado and colleagues (2017) described it as a basal neornithischian; later analyses place it within Thyreophora, most of them as an early stegosaur close to Huayangosaurus.

Diagnosis

  1. Premaxilla with posterolateral process not contacting lacrimal
  2. Elongated maxilla with elevated tooth count and increased snout length
  3. Posterior jugal process at least as long as anterior process
  4. Two supraorbitals incorporated into orbital margin
  5. Broad contact between postorbital and parietal
  6. Subcircular supratemporal fenestrae
  7. Anteriorly downturned dentary row

Species

Isaberrysaura mollensis Salgado et al., 2017

Type species

Named for the Los Molles Formation of Argentina, where the holotype was discovered.

Holotype
MOZ-Pv 6459 , Museo Provincial de Ciencias Naturales "Dr, Prof. Juan A. Olsacher"
Material
Nearly complete skull with partial postcranium: 6 cervical, 15 dorsal, sacrum with partial ilium, complete pubis, 9 caudal vertebrae, scapula part, ribs.
Horizon
Los Molles Formation, Bajocian, Middle Jurassic , 170.9–168.2 million years ago
Locality
Los Molles, Neuquén, Argentina

References

  1. Salgado, L.; Canudo, J. I.; Garrido, A. C.; Moreno-Azanza, M.; Martínez, L. C. A.; Coria, R. A.; Gasca, J. M. (2017). A new primitive Neornithischian dinosaur from the Jurassic of Patagonia with gut contents. Scientific Reports 7(1): 42778:1-10. Springer Science and Business Media LLC. doi:10.1038/srep42778

    Describes it as a basal neornithischian, but constrained searches do not reject a basal thyreophoran position.

    salgado2017a
  2. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the mass estimate.

    paul2024a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Source of the appearance features.

    jones2026a
  4. Sánchez-Fenollosa, S.; Cobos, A. (2025). New insights into the phylogeny and skull evolution of stegosaurian dinosaurs: an extraordinary cranium from the European Late Jurassic (Dinosauria: Stegosauria). Vertebrate Zoology 75: 165-189. doi:10.3897/vz.75.e146618

    Phylogenetic analysis of stegosaurian skulls recovered Isaberrysaura as a basal stegosaur.

    sánchez-fenollosa2025a
  5. Han, F.; Forster, C. A.; Xu, X.; Clark, J. M. (2018). Postcranial anatomy of Yinlong downsi (Dinosauria: Ceratopsia) from the Upper Jurassic Shishugou Formation of China and the phylogeny of basal ornithischians. Journal of Systematic Palaeontology 16(14): 1159-1187. doi:10.1080/14772019.2017.1369185

    Recovered Isaberrysaura as a basal stegosaur in phylogenetic analysis

    han2018a
  6. Raven, T. J.; Maidment, S. C. R. (2018). The systematic position of the enigmatic thyreophoran dinosaur Paranthodon africanus, and the use of basal exemplifiers in phylogenetic analysis. PeerJ 6: e4529. PeerJ. doi:10.7717/peerj.4529

    Sister to Gigantspinosaurus in its stegosaur matrix, among neornithischians in two basal-ornithischian matrices; concludes it is likely a thyreophoran needing further study.

    raven2018a
  7. Dieudonné, P. E.; Cruzado-Caballero, P.; Godefroit, P.; Tortosa, T. (2020). A new phylogeny of cerapodan dinosaurs. Historical Biology 33(10): 2335-2355. doi:10.1080/08912963.2020.1793979

    Recovers Isaberrysaura as the sister taxon of Stegosauria.

    dieudonné2020a
  8. Raven, T. J.; Barrett, P. M.; Joyce, C. B.; Maidment, S. C. R. (2023). The phylogenetic relationships and evolutionary history of the armoured dinosaurs (Ornithischia: Thyreophora). Journal of Systematic Palaeontology 21(1): 2205433. doi:10.1080/14772019.2023.2205433

    In its preferred analysis recovers Isaberrysaura as an early stegosaur, sister to Huayangosaurus; its equal-weights and Bayesian analyses place both outside Eurypoda.

    raven2023a